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Summary

Emitting b radiation with a half-life of 5730 years, Carbon 14 follows the cycle of the stable element C, one of the components of the living materials, in which it is diluted. Carbon-14 is indeed around 10^-12 times less abundant than stable carbon. The main source of exposure is due to naturally occurring ¹⁴C (cosmogenic origin).

About the impact of chronic releases, the consensus is that ¹⁴C behaves in the same manner as the stable ¹²C isotope (representing 99% of carbon). Carbon-14 transfers between two compartments of the environment are generally evaluated based on the assumption that the isotopic ratio between the radioactive carbon and the stable carbon (considered to be ¹²C) is maintained, between the organism and the surrounding environment. This assumes that the transfer of the trace radionuclide ¹⁴C is identical to that of ¹²C and that equilibrium between the two compartments is achieved. Under this assumption, the impact on the environment and populations can only be evaluated for environmental releases and concentrations that are constant over time, generally by using average annual values.

The environmental toxicity of ¹⁴C is only related to radioactive emissions of the pure, low-energy b type. This toxicity is mainly the result of internalisation, essentially by ingestion.

Characteristics

Chemical characteristics

Carbon-14 (¹⁴C) is a radioactive carbon isotope present in infinitesimal quantities in the atmosphere. Carbon-12 and carbon-13 are the stable carbon isotopes and respectively represent 98.9% and 1.1% of the total carbon. Carbon-14 only exists in trace quantities. The chemical forms of ¹⁴C vary according to the method of production. In the environment, ¹⁴C exists in two main forms:

– as ¹⁴CO₂, it acts as stable carbon dioxide, which means it can remain in gas form in the air, becoming bicarbonate and carbonate in water

– during photosynthesis, ¹⁴CO₂ is incorporated into the organic material, forming its carbon skeleton. Equilibrium between the specific activity of atmospheric carbon and that of organic material is then finally reached and maintained by carbon recycling.

Nuclear characteristics

Carbon has 15 isotopes, with masses of 8 to 22. Only isotopes 12 and 13 are stable. The radioactive half-life is higher than a year only for carbon-14, its maximum value for the other isotopes being around 20 minutes.Carbon-14, a beta^– emitter, gives rise to stable ¹⁴N with 100% yield.

Origins

Natural origins

Natural ¹⁴C results from cosmic neutrons acting on nitrogen atoms in the stratosphere and in the upper troposphere (¹⁴N +n →¹⁴C+¹p). The annual production level is around 1.40 x 10¹⁵ Bq and the atmospheric stock of carbon-14 at equilibrium is around 140 x 10¹⁵ Bq (UNSCEAR, 2008). Production fluctuates due to variation in cosmic ray intensity. This fluctuation results from various factors that are not yet well understood, but mainly include the 11-year solar cycle and, on a larger temporal scale, variations in the terrestrial magnetic field that serves as a shield against cosmic rays (Garnier-Laplace et al., 1998).

Artificial origins

During nuclear explosions, the emitted neutrons interact with atmospheric nitrogen, as cosmic neutrons do, to form carbon-14, according to the same reaction as above: ¹⁴N +n →¹⁴C+¹p.

 Nuclear explosions carried out before 1972 released around 3.5 x 10¹⁷ Bq of carbon-14. Later explosions increased this amount by around 1% (UNSCEAR, 2008).

 In nuclear reactors, carbon-14 is produced from reactions in the fuel, the core structural materials and the moderator. The production rate depends on the spectrum and the neutron flux, on cross-sections and on the concentration of the following target elements: uranium, plutonium, nitrogen and oxygen. Water in the primary coolant circuit of pressurised water reactors contains excess hydrogen that combines with oxygen from radiolysis. In this reducing environment, compounds such as methane (CH₄) and ethane (C₂H₆) form. Most of the carbon-14 released in a pressurised water reactor is in the form of alkanes. Various estimations indicate that the annual production rate for a light water reactor (pressurised or boiling water reactor) is between 0.5 and 1.9 x 10¹² Bq/GWe/year, with carbon-14 mainly taking organic forms (CH₄). The rest is released during reprocessing, or remains in the fuel cladding and is later disposed of as solid waste (Garnier-Laplace et al., 1998).

• Releases by irradiated fuel reprocessing plants

Spent nuclear fuel ¹⁴C is released during the dissolution step in reprocessing plants. Depending on the operating mode, these releases are continuous or discontinuous. In reprocessing plants that use the PUREX process (e.g. the AREVA NC La Hague plant), the ¹⁴C is mainly released as CO₂. Commissioning of the UP3 and UP2-800 plants at La Hague resulted in increased annual gaseous ¹⁴C releases starting in the early 1990s. In 2009, the gaseous releases of carbon-14 at the site corresponded to 1.45 x 10¹³ Bq and the liquid releases corresponded to 6.12 x 10¹² Bq. Carbon-14 in fuel cladding is not released during dissolution and remains trapped. It is disposed of later as solid waste.

At the Sellafield plant in the UK in 2009, the ¹⁴C gaseous releases reached 3.8 x 10¹¹ Bq and the liquid releases, 8.2 x 10¹² Bq (Sellafield Ltd, 2009).

• Various sources (medical, industrial, research) 

 In research, carbon-14 is widely used in carbonate form for isotopic labelling of molecules. The activities used are greater than 1 GBq. For example, carbon-14 is used to study metabolic dysfunction related to diabetes and anaemia. It can also be used as a marker to track the metabolism of new pharmaceutical molecules. More generally, carbon-14 can be used to uncover new metabolic pathways, and to identify their normal functioning and any departures from it, e.g. for photosynthesis (Calvin and Benson, 1948) or, more recently, for the methylaspartate cycle in halobacteria (Khomyakova et al., 2011).

It is assumed that all ¹⁴C used for labelling molecules will be released into the atmosphere as CO₂. According to UNSCEAR, the annual production of ¹⁴C is equivalent to 3 x 10¹⁰ Bq per million inhabitants in developed countries and to 5 x 10¹³ Bq worldwide. This estimation is based on the results of a 1978 US study. A 1987 British estimation led to values at least twice as high (UNSCEAR, 1993).

Environmental concentrations

• Carbon-14 background in the environment and changes over the last 60 years

In the terrestrial environment, the consensus (relatively well supported by observations) is that the specific activity, expressed in becquerels of ¹⁴C per kilogram of total carbon, is constant in the environmental components and at equilibrium with the specific activity of atmospheric CO₂ (Roussel-Debet et al., 2006, Roussel-Debet, 2007, 2009). Uninfluenced by nuclear facilities, the ¹⁴C specific activities for the biological compartments of the terrestrial environment reached their maximum values (more than 400 Bq/kg of C) in the mid-1960s, due to fallout from atmospheric nuclear arms testing, then at its height (Figure 1). These activities have slowly decreased since then (by less than 0.5% per year) with the end of testing and the continuous increase in CO₂ from fossil fuels (gasoline, coal, gas). The specific activities of terrestrial biological compartments are currently around 238 Bq ¹⁴C/kg C (2009 measurements), which is very close to 1950 values (226 Bq/kg C), before atmospheric testing.

In aquatic environments, the specific activity of ¹⁴C varies with its dilution in carbon substances, particularly carbonates from old sedimentary rocks lacking carbon-14. Unlike the terrestrial environment, ¹⁴C in freshwater ecosystems is not in equilibrium with atmospheric CO₂: freshwater-specific activity is then lower, around 200 Bq/kg C.

Based on the specific activity and the total proportion of carbon in the various environmental matrices (air, plants, animals, and thus food products), the activity concentration for the ¹⁴C in these matrices can be estimated (Figure 2). The more carbon the product contains (sugars, oils, grains, etc.), the higher the activity.

Depending on the proportion of carbon per wet mass unit of food product, the activity concentration of these products varies between less than 15 (lettuce, mussels) and more than 80 (grains) Bq/kg wet. Atmospheric activities vary from 3 x 10^-2 to 7 x 10^‑2 Bq/m³. Carbon-14 thus has the highest environmental activities amongst the radionuclides released from nuclear facilities.

• Influence of nuclear facilities

 With atmospheric releases of around 2 x 10¹³ Bq/year of ¹⁴C, mainly as CO₂, the AREVA-NC La Hague plant causes an added carbon-14 activity (above the natural background) regularly detectable in the site’s terrestrial environment, leading to specific activities of 500 to 1000 Bq/kg C, and occasionally 2000 Bq/kg C. The corresponding activity concentrations range from 20 to 140 Bq/kg of wet grass or vegetables, compared with a background of around 5 to 20 Bq/kg of wet material in this type of matrix. In milk and meat, this contamination is also significant although much less so, probably due to a feeding component outside the area influenced by the atmospheric releases. Note that the maximum radioactivity in the air at ground level after dispersion, set at 1 Bq/m³ by the French order authorising AREVA-NC La Hague releases, would correspond to specific activity in plants of 5000 Bq/kg C, if attained at all times throughout the year.

The carbon-14 addition around nuclear power plants (atmospheric releases of 0.2 to 1×10¹² Bq/year) is extremely limited: the associated specific activity is around 3 Bq/kg C in addition to the 243 Bq/kg of C representing the average background for 1994-2003 (Roussel-Debet et al., 2006), i.e. an added activity of around 1%. This low level is the result not only of low releases, but also of a clear predominance of releases in the form of methane (CH₄), which plants cannot assimilate.

In rivers, the carbon-14 released by nuclear power plants is diluted in the dissolved stable carbon from carbonates, which are found in sediment. This significantly decreases the specific activity of carbon-14 in physical components. For semi-underwater aquatic plants, dilution also occurs in the atmospheric CO₂ used during photosynthesis; the associated specific activities rarely exceed 400 Bq/kg C. For reasons that remain to be elucidated, fish do not seem to benefit from these dilution phenomena. Their specific activity under the influence of nuclear power plants regularly exceeds 600 Bq/kg C and may reach 1000 Bq/kg C.

Metrology, analytical techniques and detection limits

 Carbon-14 in an environmental sample may be quantified by activity measurement or by atom counting. These two destructive techniques require converting the sample to CO₂ (Maro et al., 2008).

Activity measurement 

The carbon contained in the test portion is transformed to carbon dioxide from which a sample is prepared for measurement by liquid scintillation (AFNOR, 2006).

Two sample preparation methods are mainly used: combustion by oxydiser and benzene synthesis (Fournier et al., 1999).

Preparation of samples by oxydiser

The sample is placed in a cellulose cone, which is inserted in a platinum filament. The entire unit is placed in a combustion chamber. Voltage applied to the ends of the filament in the presence of O₂ causes combustion of the sample. The combustion gases are pushed by nitrogen in a column containing Carbosorb®, which traps CO₂ in the form of carbamate. This mixture is eluted from the column by the scintillation liquid and then collected for measurement.

The oxydiser allows to prepare several samples per day for counting. The test portions are generally less than 0.5 g of the dry sample. They must be rich enough in carbon to undergo a complete oxidation.

Combustion yield must be determined on a reference sample labelled for ¹⁴C. This reference sample must be as close as possible in nature and composition to the samples to be analysed.

The ¹⁴C naturally contained in the combustion cone cellulose contributes to the increase in background and thus in higher measurement uncertainty. Background must thus be determined as precisely as possible.

The expression of the sample’s activity in Bq of ¹⁴C per kg of carbon also requires measuring its elementary carbon content, generally by gas chromatography.

The measurement uncertainty, around 30 to 40% (k=2) for activities of around 260 Bq.kg^-1 of carbon (natural level in the environment), makes it difficult to detect low concentrations with this method. This uncertainty can, however, be reduced by increasing the test portions or by combining the measurements of several test portions from the same sample. 

• ¹⁴C analysis by benzene synthesis

The sample is burned in the presence of under pressure oxygen in a combustion bomb. The CO₂ produced is then reduced by a heated reaction with lithium to obtain lithium carbide (Li₂C₂), the hydrolysis of which produces acetylene (C₂H₂), which is trimerised by catalysis in benzene (C₆H₆).

Atom counting

• Principal

• ¹⁴C measurement by accelerator (AMS)

After decarbonation and combustion of the sample, the CO₂ obtained is reduced by H₂ in the presence of powdered iron. The carbon is deposited on the powdered iron and the mixture is pressed into a target to allow for measurement by mass spectrometry. The sample’s ¹⁴C activity is calculated by comparing ¹⁴C, ¹³C and ¹²C beam intensities, measured sequentially, with the CO₂ reference intensities.

The test portions consist in around 0.10 g of material. Uncertainty at the level of the environmental background corresponds to 2 to 3% (k=2).

Accelerator Mass Spectrometry (AMS) is characterised by high sensitivity, which is obtained by good separation of ¹⁴C from other ions having the same mass (particularly nitrogen). It is favoured for low-quantity samples or those containing low levels of organic materials (soil, sediment, sea water, air samples, etc.).

 The activity concentration results are expressed in Bq/kg of dry material, Bq/kg of wet material or Bq/kg of carbon.

The counting vial is prepared by weighing out synthesised benzene and scintillants. Spectroscopy-quality benzene is added if needed.

The activity of the ¹⁴C present in the vial is then measured using liquid scintillation. The result can be directly converted into Bq/kg of carbon.

The test portions consist of 7 to 10 g of finely ground, dry sample. The chemical processing time for one sample is 3 days, 2 more days being necessary for counting. Uncertainty at the level of the environmental background corresponds to 6 to 7% (k=2).

This method is suitable for solid dry samples containing high carbon and for water matrices in the form of carbonate (e.g. barium carbonate). For water matrices, CO₂ is extracted from the sample by acid attack (e.g. addition of orthophosphoric acid) rather than by combustion bomb. The rest of the protocol does not change.

The analysis methods involving oxydiser or benzene synthesis are not well suited for carbon-poor matrices, such as soil and sediment.  

Mobility and bioavailability in terrestrial environments

Carbon-14 data and the models on the fate of this radionuclide in terrestrial environments (Scott et al., 1991; Sheppard et al., 1994; Garnier-Laplace et al., 1998; Fontugne et al., 2004; Tamponnet, 2005a and b) are based on knowledge of the carbon cycle at equilibrium (Ouyang and Boersma,1992). Carbon-14 is integrated in the carbon cycle, which is very complex due to the presence of inorganic and organic carbon, in solid, liquid or gaseous forms (Figure 3).

Soil

The average quantity of carbon in organic material of cultivated soils is in France around 20 g of carbon per kg of dry soil. The soil solution carbon can be in the form of CO₂, carbonate (CO₃^2-) or bicarbonate (HCO₃^–), depending on the pH and the quantity of calcium ions.

Plants

The average CO₂ quantity of gaseous soil phase varies from 0.5 to 1%. It increases in the presence of plants (due to root respiration, the pH decreases and the dissolved CO₂ increases by around 38% per pH unit).

Root absorption of carbon by plants is negligible. Root incorporation from carbonate ions, poorly understood, appears to represent 5% maximum of the total carbon incorporated in a plant. Most of the carbon is assimilated by leaves as CO₂ during photosynthesis. Isotopic discrimination, which depends on the plant’s photosynthetic cycle, is negligible (¹⁴C / ¹²C ratio less than 5% maximum between the plant and the atmospheric CO₂).

CO₂ emanation from the mineralisation of organic soil residues and root respiration tends to increase the concentration of CO₂ in the air, at the plant cover level. The daily flux of CO₂ released by the soil appears to be 2 to 13 g per m². This flux appears to contribute around 10% to the total carbon assimilated by leaves during photosynthesis (Le Dizès-Maurel et al., 2009).

Animals

More than 99% of the carbon incorporated by livestock comes from their feed. Carbon from inhalation is negligible, as is carbon from ingestion of water or soil.

Mobility and bioavailability in continental aquatic environments

Carbon-14 data and the models on the fate of this radionuclide in continental aquatic environments (Sheppard et al., 1994; Garnier-Laplace et al., 1998) are based on knowledge of the carbon cycle at equilibrium (Stumm and Morgan, 1981; Amoros and Petts, 1993).

The ¹⁴C organic compounds released by nuclear facilities are incorporated into the organic carbon of the hydrosystem that receives them (Figure 4).

The inorganic carbon released by nuclear facilities or present in the hydrosystem takes the form of species in the carbonate system (CO_{2 aqueous}/HCO₃^–/CO₃^2-), which is one of the main chemical systems involved in controlling freshwater pH. In most running waters, pH varies from 6 to 9, with bicarbonate forms dominating. Carbon-14 in liquid effluents, released as carbonates, is incorporated in the inorganic carbon. Isotopic dilution varies according to atmospheric exchanges, run-off contribution and exchanges with hydrogeological systems. In all cases, the specific activity of inorganic ¹⁴C must be considered in terms of the value measured in situ for total CO₂, according to the following equation: [CO2]total = [CO2]aq + [HCO3–] + [CO32-].

Water and sediment

Carbon-14 is integrated in the carbon cycle of continental hydrosystems where the main forms are organic carbon (dissolved organic carbon/DOC, 1 to 3 mg of carbon per litre; and particulate carbon, which is highly variable from one hydrosystem to another) and inorganic carbon (essentially in the form of dissolved bicarbonate, 1 to 120 mg of carbon per litre). Humic and fulvic acids represent from 50 to 75% of the DOC, whilst the colloidal forms represent 20%. The particulate forms are also varied: allogenic detrital forms, living organisms and compounds from their decay.

Plants

Transfers to plants are governed by photosynthesis. Photosynthesis is mainly carried out by higher plants, periphytic and planktonic algae, and cyanobacteria. In schematic terms, it can be considered the dominant biological process that influences the concentration of inorganic carbon in the hydrosystem; respiration and bacterial fermentation can be considered negligible. On average, the concentration of total carbon in freshwater plants is 5 x 10⁴ mg of carbon per kilogram of wet material.

Animals

Transfers to animals are governed by ingestion. For aquatic organisms, the processes of respiration and osmoregulation that use inorganic carbon are similarly negligible in the animal’s carbon balance compared to transfers via food ingestion. Carbon concentration in animals varies from one species to another.

Mobility and bioavailability in marine environments

The mechanisms of ¹⁴C transfer in marine and freshwater environments are identical, and the models are based on the assumption that equilibrium is reached due to environmental carbon recycling. Most of the ¹⁴C released into the sea is in dissolved inorganic form and is incorporated by organic material. Close to release points, when the variations in the quantities released are rapid and large, equilibrium between the specific activities of the organic material and the sea water is not always reached (Fiévet et al., 2006).

Sea water

In the Channel, the research of Douville et al. (2004) indicates that the ¹⁴C in sea water at Cap de La Hague mainly takes the form of dissolved inorganic carbon (dissolved CO₂, HCO^3-, CO₃^2-), which is the predominant form of carbon in sea water, with activities between 300 and 800 Bq.kg^-1 of carbon.

Seeweed

As in the case of freshwater plants, the transfer of ¹⁴C to seaweed occurs by photosynthesis. The total carbon concentration in seaweed is roughly equivalent to the freshwater plant concentration. This concentration was found to be 8 ´ 10⁴ mg of carbon per wet kilogram of the brown seaweed Fucus serratus, an example of the algal flora of north-western European coasts. Used as a model compartment for ¹⁴C exchanges between sea water and a photosynthetic organism, this alga was used to estimate a biological half-life for ¹⁴C of around 5 months. The value of this parameter explains the absence of equilibrium close to the release point (Cap de La Hague), where the variations in seawater ¹⁴C concentration are large and rapid, due to the history of releases by the AREVA NC reprocessing plant (Fiévet et al., 2006).

Animals

As in the case of the terrestrial and freshwater animals, transfers to marine animals are mainly governed by ingestion. Although cell membranes are permeable to bicarbonates dissolved in water, the quantity of absorbed carbon that they represent is low compared to the carbon incorporated in organic material. The carbon concentration by unit of wet weight in marine animals varies a great deal from one organism to another, especially due to the different water contents (e.g. jellyfish, bivalves, gastropods, echinoderms, crustaceans, fish, etc.). The limpet has been used as a model compartment for ¹⁴C exchanges between sea water and a grazing animal, making it possible to estimate a biological half-life for ¹⁴C of around 8 months. This half-life integrates all the transfer pathways between the sea water and the gastropod’s flesh, including ¹⁴C incorporation from the animal’s food source. Biological half-life is estimated to be around 1 month in mussels, which are used as a model of filtering organisms (Fiévet et al., 2006). Although there is great variability in the speed of carbon recycling between sea water and the different biological compartments, these half-life values clearly explain why a state of equilibrium is not reached where the sea water ¹⁴C concentration may vary rapidly, close to release points for example.

Mobility and bioavailability in semi-natural ecosystems

This section is based on the international literature review conducted for the revision of the IAEA handbook on parameter values for predicting radionuclide transfer in terrestrial and temperate continental aquatic environments (IAEA, 2010).

Forests

There is no specific information on the mobility and bioavailability of carbon-14 in forest ecosystems.

Artic ecosystems

There is no specific information on the mobility and bioavailability of carbon-14 in arctic ecosystems.

Alpine ecosystems

There is no specific information on the mobility and bioavailability of carbon-14 in alpine ecosystems.

Environmental dosimetry

The effects of exposure to ionising radiation depend on the quantity of energy absorbed by the target organism, expressed by a dose rate (µGy/h). This dose rate is evaluated by applying dose conversion coefficients (DCCs, µGy/h per Bq/unit of mass or volume) to radionuclide concentrations in exposure environments or in organisms (Bq/unit of mass or volume).

The characteristic ¹⁴C DCCs were determined without considering decay products and without RBE weighting. Version 2.3 of EDEN software (Beaugelin-Seiller et al., 2006) was used, taking into account shape, dimensions and chemical composition of the organisms and of their environments, as well as their geometrical relations. The modelled species were chosen as examples.

Except in the particular case of the fescue (10^-3 µGy/h per Bq/kg wet), internal exposure is generally characterised by DCCs of around 10^-5 µGy/h per Bq/kg wet.

External exposure is characterised by lower DCCs that vary according to the organism, within a range of 10^-10 and 10^-5 µGy/h per Bq/kg.

 For more details on how to calculate DCC, see the Environmental Dosimetry Sheet.

Environmental toxicity

 

 

 

 

 

 

 

 

 

 

History of Taxonomy

Science creates categories and classification systems to make sense of the natural world. In the case of living organisms, which include millions of species that evolved through several billions of years of Earth history, and whose characteristics (especially fossil species) and evolutionary relationships are often imperfectly understood, classification becomes arbitrary. Add to this the fact that specialists working in different fields may have different approaches or preferences, and it is easy to see how the subject can become confusing, and ideas and methodologies have changed radically over time.

Aristotle was the first to give the first detailed classification of living things. His classification of animals was:

Blooded (vertebrates)
Viviparous quadrupeds (land mammals)
Birds
Oviparous quadrupeds (reptiles and amphibians)
Fish
Cetaceans (Aristotle did not realize their mammalian nature)
Bloodless (invertebrates)
Land arthropods (insects, arachnids, myriapods)
Aquatic arthropods (mostly crustaceans)
Shelled animals (shelled mollusks, echinoderms, etc.)
Soft animals (cephalopods, etc.)
Plant animals (cnidarians, etc., which superficially resemble plants)

However, he had made no effort to classify plants or fungi. His ideas were essentially based on the idea of the scala naturae, the “Natural Ladder” according to which the entire natural world could be arranged in a single continuum. During the medieval period, this became incorporated into the idea of the Great Chain of Being.

Classical and medieval thinkers used logical and philosophical categories, but these were based on the most general principles, and while perhaps useful for abstract philosophy, were not much use in understanding the natural world. In the theocratic Middle Ages, this didn’t matter much, but with the progressive advance of knowledge during the Renaissance, the Age of Reason, and the Enlightenment, there developed an interest in the secular world for its own sake. Botanists especially were fascinated by exoteric new plants discovered during the voyages of exploration. It is not coincidental then that the father of modern biological classification was a botanist, Carl Linne, better known by his Latin name Linnaeus. Linnaeus’s simple yet brilliant idea was to distinguish nomenclature – the science of naming – from description. He, therefore, rejected the long-winded descriptive names of plants used by his predecessors and contemporaries and replaced them with a simple two-name system, a generic and a specific (think surname and given name, e.g. Smith, John). These were then grouped in hierarchies such as class, order, and so on. With only slight refinements, the Linnaean system is the scientific, biological classification system still used today.

Scientists and naturalists like Linnaeus in Sweden, and later the anatomist and naturalist Georges Cuvier in France, and Owen in England, and their colleagues and co-workers, established in the 18th and early 19th century the science of what we now know as Taxonomy. Taxonomy is concerned with discovering, identifying, describing, and naming organisms. For this to work it requires institutions to hold collections of these organisms, with relevant data, carefully curated: such institutes include Natural History Museums, Herbaria, and Botanical Gardens. Richard Owen for example established the British Museum of Natural History in London, where his statue still resides.

Linnaeus, like his 18th-century contemporaries, had a static, biblical view of the world. All the species that existed and that he described were the same as those created by God, and every species that ever lived was still alive today. This simple worldview was undermined in the late 18th and early 19th century by the discovery of fossil species different from anything alive. This led to the birth of paleontology, under men like Cuvier and Owen. Cuvier, the father of paleontology, who was the first to name and correctly identify many fossil animals (e.g.: Pterodactylus, Mosasaurus, Didelphys, Palaeotherium) was still a creationist but explained the existence of strange armoured fish, ichthyosaurii, tertiary mammals, mastodons, and the rest in terms of repeated catastrophies, after which God would recreate the world. The biblical flood was considered the most recent of these catastrophes.

Owen, who named the order (now superorder) Dinosauria, instead adopted a Goethean concept of evolving archetypes (but not of physical evolution; Owen was strongly opposed to Darwin’s theory when it came out). By these sorts of mechanisms, Cuvier and Owen could explain the existence of antediluvial (before the flood) monsters. All this changed with Darwin’s discovery of the principle of evolution. Darwin, Huxley, and Haeckel established the evolutionary paradigm, and, like Cuvier and Owen, had no problem identifying prehistoric life with Linnaean categories. What evolution did was to make the Linnaean system more dynamic? Thus, Huxley was able to show that Archaeopteryx, the first bird (Class Aves) was also a transitional form between reptiles (Class Reptilia) and modern birds. This synthesis of Darwinian science and Linnaean taxonomy was further elaborated on in the mid-20th century by vertebrate paleontolgists Romer and Simpson and came to be later known as Evolutionary Systematics

In the 1980s, an alternative to Evolutionary Systematics, called Phylogenetic Systematics, or Cladistics became popular, especially among vertebrate paleontologists. Cladistics is more properly considered under the next Unit, Phylogeny. The central difference between the Linnaean and Cladistic systems is that one is a taxonomic, classification system, the other a means of constructing phylogenetic hypotheses; or in less jargonesque language, deciding which of several possible evolutionary trees is likely to be the more correct one (which doesn’t mean it is the right one, as discoveries can always overturn the current hypotheses) [1]. Over the past few years, an attempt has been made to develop a formal, cladistic system of taxonomy and nomenclature to replace the linnaean system, called the Phylo Code, but this is yet to catch on at a wider level in biology.

One might suppose that classification should reflect phylogeny, and that phylogeny would automatically result in a superior classification system, but this is not necessarily the case. Taxonomies may involve organisms that appear to be closely related but are not, phylogenies can result in unwieldy systems, or phylogenetic definitions can be overturned by discoveries and hypothesis Taxonomies can be overturned as well, but are generally more robust (Benton 2007).. The most reasonable approach therefore is to acknowledge the usefulness of both descriptive classification and phylogenetic hypotheses as two equally partial and complementary means of understanding the natural world. MAK120229

Notes:

[1] Contrary to popular belief, cladistics does not describe the actual evolutionary path of life. That is, it is not concerned with or describes the evolution of later organisms from common ancestors in the way that, say, Darwin or more recently Richard Dawkins do, and what the Evolutionary systematics of Romer and Simpson also describes. It simply provides a way of generating hypotheses regarding the way living organisms are related to each other. Cladograms, in other words, are not evolutionary trees. What cladistics does do is provide a more precise and verifiable method of creating hypotheses regarding the evolutionary relationships of past and current organisms (Phylogeny, a word invented in the late 19th century by Haeke), but used here ina somewhat different context).

 

 

 

I. The history of Biological Control may be divided into 3
periods:

A. The preliminary efforts when living agents were released 
haphazardly with no scientific approach. Little precise information
exists on successes during this time. Roughly 200 A.D. to 1887 A.D.;

B. The intermediate period of more discriminating BC started with
the introduction the Vedalia beetle, Rodolia cardinalis Mulsant, for
control of the cottony cushion scale in 1888. The period extended from 1888
to ca. 1955; and

C. The modern period is characterized by more careful planning and more
precise evaluation of natural enemies. The period from 1956 to the present.

II. Early History: 200 A.D. to 1887 A.D.

A. 200 A.D. to 1200 A.D: BC agents were used in augmentation

1. The Chinese were the first to use natural enemies to control insect pests.
Nests of the ant Oecophylla smaragdina were sold near Canton in the
3rd century for use in the control of citrus insect pests such as
Tesseratoma papillosa (Lepidoptera)

2. Ants were used in 1200 A.D. for control of date palm pests in Yemen
(south of Saudia Arabia). Nests were moved from surrounding hills
and placed in trees

3. Usefulness of ladybird beetles recognized in the control of aphids and scales
in 1200 A.D.

B. 1300 A.D. to 1799 A.D.: BC was just beginning to be recognized.

1. Aldrovandi noted the cocoons of Apanteles glomeratus on a parasitized
Pieris rapae in 1602 A.D., but thought cocoons were insect eggs

2. Vallisnieri interpreted the phenomenon of insect parasitism (parasitoid)
in 1706 A.D. However the honor of being the first to understand insect
parasitism may belong to the microbiologist Van Leeuwenhoek who
illustrated and discussed a parasite of a sawfly that feeds on willow in a
publication in 1701.

3. The first insect pathogen was recognized by de Reaumur in 1726. It
was a Cordyceps fungus on a noctuid

4. In 1734, de Reaumur suggested to collect the eggs of an “aphidivorous
fly” (actually a lacewing) and place them in greenhouses to control
aphids

5. The mynah bird, Acridotheres tristis, was successfully introduced from
India to Mauritius (off the coast of Madagascar) for control of the red
locust, Nomadacris septemfasciata, in 1762

6. In the late 1700s, birds were transported internationally for insect
control

7. Control of the bedbug, Cimex lectularius, was successfully
accomplished by releases of the predatory pentatomid Picromerus
Bidens in 1776 in Europe

C. 1800 A.D. to 1849 A.D. During this period advances were made in
Europe which was both applied and basic

1. In the 1800’s, Darwin discussed “Ichneumonids” as natural control
factors for cabbage caterpillars

2. Malthus (in England) published Essays on the Principles of
Population in 1803

3. Hartig (Germany) suggested the rearing of parasites from parasitized
caterpillars for mass releases in 1827

4. Kollar (Austria) put forth the concept of “natural control” in 1837

5. Verhulst (1838) described the logistic growth equation but the idea
lay dormant until 1920 when rediscovered by Pearl. Expressed
the idea of “environmental resistance”.

6. During the 1840s releases of predators were used for control of the
gypsy moth and garden pests in Italy

D. 1850 to 1887. During this time the focus on BC switched to the United
States.

1. From 1850 to 1870 enormous plantings of many crops were being
grown in the United States (especially California) and were initially
free of pests. Later farmers saw their crops destroyed by hordes of
alien pests

2. Asa Fitch (New York) suggested importing parasites from Europe
to control the wheat midge, Contarinia tritici, in 1856. No action
was taken. In 1860 parasites were requested from Europe, but none
were received

3. During this period, Benjamin Walsh (Illinois) actively worked
for the importation of natural enemies to control the exotic insects
in the United States but was unsuccessful. Fortunately, he
influenced Charles V. Riley greatly who was in Missouri during
Walsh’s campaign

4. The first practical attempt at BC of weeds occurred in 1863 when
segments of the prickly pear cactus, Opuntia vulgaris, infested with
the imported cochineal insect, Dactylopius ceylonicus, were
transported from northern to southern India

5. Riley conducted the 1st successful movement of parasites for
biological control when parasites were moved from Kirkwood,
Missouri, to other parts of the state for control of the weevil
Conotrachelus nenuphar in 1870

6. LeBaron transported apple branches infested with oyster-shell scale
parasitized by Aphytis mytilaspidis from Galena to Geneva,
Illinois in 1871

7. In 1873 Riley sent the predatory mite Tyroglyphus phylloxerae to
France to control the grape phylloxera. The mite was established
but did not exert control as hoped.

8. Trichogramma sp. (egg parasites) were shipped from the U.S. to
Canada for control of lepidopterous pests in 1882

9. In 1883 the USDA imported Apanteles glomeratus from England
for control of P. rapae (the imported cabbageworm). Parasites
were distributed in DC, Iowa, Nebraska, and Missouri. First
intercontinental shipment of parasites.

III. The Intermediate Period: 1888 to 1955

A. 1888 to 1889: The Cottony Cushion Scale Project

1. Cottony cushion scale, Icerya purchasi Maskell, was introduced into
California in ca. 1868 around the Menlo Park (CA) area (near San
Francisco)

2. It spread to southern California and by 1887 was threatening to destroy
the infant citrus industry

3. C. V. Riley (Chief of the Division of Entomology, USDA) employed
Albert Koebele and D. W. Coquillett in research on control of the
cottony cushion scale

4. No method was working in 1887

5. Koebele was sent to Australia in 1888 to collect natural enemies of the
scale

6. He sent ca. 12,000 individuals of Cryptochaetum iceryae and 129
individuals of Rodolia cardinalis (the vedalia beetle)

7. Within the year, the cottony cushion scale ceased to be a substantial
pest

8. The vedalia beetle controls the scale mainly in the inland desert areas
and C. iceryae controls it in the coastal areas of California.

B. 1890 to 1899: Growing pains for BC

1. Following the success in 1889, California put pressure on Riley to
send Koebele back to Australia in search of parasites for other scales
parasites in California

2. Koebele went on foreign exploration, but on his return, he was recalled
from California. Koebele resigned from his position and went to work for
the Republic of Hawaii in 1893. He worked on BC projects in the
interest of Hawaii until 1912 when he retired due to ill health.

3. Due to the success of the Vedalia beetle, great emphasis was placed on
importation of coccinellids for BC initially in California and Hawaii. It
is believed that California was set back many years by promoting
mostly biological control projects and not researching alternative
control methodologies.

4. L. O. Howard replaced C. V. Riley as Chief of the Division of
Entomology, USDA in 1894. Howard was prejudiced against BC due to
the problems he saw in California

5. George Compere began as a foreign explorer for California in 1899

C. 1900 to 1930: New faces and more BC projects

1. The Gypsy Moth Project in New England (1905-1911). W. F. Fiske
was in charge in Massachusetts. Howard conducted foreign exploration
in Europe and arranged for parasites to be imported to the U.S. Many
prominent entomologists employed on the project: Harry Scott Smith,
W. R. Thompson, P. H. Timberlake.

2. The Lantana Weed Project in Hawaii (1902) First published work on
BC of weeds. Koebele went to Mexico and Central America looking
for phytophagus insects which were sent to R. C. L. Perkins in
Hawaii.

3. The Sugar-cane Leafhopper Project in Hawaii (1904-1920). Hawaiian
Sugar Planters Association (HSPA) created a Division of Entomology
in 1904. R. C. L. Perkins was appointed superintendent. The staff consisted of O. H.

Swezey, G. W. Kirkaldy, F. W. Terry, Alexander
Craw, and Albert Koebele. Later Frederick Muir was employed due to
Koebele’s health problems. Muir found the highly effective predator
Tytthus (= Cyrtorhinus) mundulus (Miridae) in Queensland, Australia,
in 1920.

4. Berliner described Bacillus thuringiensis in 1911 as the causative agent of
bacterial disease of the Mediterranean flour moth

5. Prof. H. S. Smith was appointed superintendent of California State
Insectary, Sacramento, CA, in 1913. The facility moved to the University
of California’s Citrus Experiment Station in 1923 (now UC Riverside).
Smith started another facility in Albany, CA, in 1945. Riverside and
Albany (UC Berkeley) is made up Department of Biological Control, UC.

6. The USDA Laboratory for Biological Control was established in France in 1919.

7. The Imperial Bureau of Entomology created the Farnham House
Laboratory for BC work in England in 1927. This was later directed by
W. R. Thompson in 1928.

D. 1930 to 1955: Expansion and decline of BC

1. From 1930 to 1940 there was a peak in BC activity in the world with
57 different natural enemies were established at various places.

2. World War II caused a sharp drop in BC activity.

3. BC did not regain popularity after WW II due to the production of
relatively inexpensive synthetic organic insecticides. Entomological
research switched predominantly to pesticide research.

4. In 1947 the Commonwealth Bureau of Biological Control was
established from the Imperial Parasite Service. In 1951 the name was
changed to the Commonwealth Institute for Biological Control (CIBC).
Headquarters are currently in Trinidad, West Indies.

5. In 1955 the Commission Internationale de Lutte Biologique contre les
Enemis des Cultures(CILB) was established. This is a worldwide
organization with headquarters in Zurich, Switzerland. In 1962 the
CILB changed its name to the Organisation Internationale de Lutte
Biologique contre les Animaux et les Plants Nuisibles.
This organization is also known as the International Organization for
Biological Control (IOBC). Initiated the publication of the journal
“Entomophaga” in 1956, a journal devoted to biological control of
arthropod pests and weed species.

IV. The Modern Period: 1957 to Present.

A. In 1959, Vern Stern et al. (1959) conceived the idea of economic injury
level and economic threshold which would permit growers to make
informed decisions on when they needed to apply control tactices in their
cropping systems and therefore eliminated the need for scheduled pesticide
treatments.

B. Interest developed nationwide in ecology and the environment after 1962
with the publishing of the Rachel Carson’s book “Silent Spring.”

C. “Silent Spring” helped stimulate the implementation of the concept of
Integrated Pest Management (IPM) in the late 1960’s, and biological
control was seen as a core component of IPM by some. More emphasis
was placed on conservation BC than classical BC.

D. In 1964, Paul DeBach and Evert I. Schliner (Division of Biological
Control, University of California, Riverside) publish an edited volume
titled “Biological Control of Insect Pests and Weeds” which becomes a major reference

source for the biological control community. This was a California-based book

with international application.

E. In some areas in the USA (e.g., California, North Carolina, Kansas,
Texas), IPM scouting was commercialized in the 1970’s and natural
enemies were relied upon to suppress pests in crops such as cotton,
alfalfa, citrus, soybeans, and other crops.

F. During the 1970s and 1980’s, Brian Croft and Marjorie Hoy made
impacts by using pesticide-resistant natural enemies in cropping systems.

G. In 1983, Frank Howarth published his landmark paper titled “Biological
Control: Panacea or Pandora’s Box” and significantly impacted classical
BC efforts by concluding that classical BC of arthropods significantly
contributed to extimction of desirable species (e.g., endemic).

1. This eventually forced a rethinking of legislative guidelines as well as
introduction methods which are still being changed today.

2. In Hawaii, BC efforts were diminished significantly and have not risen
to levels before 1985.

3. Research efforts into this area were stimulated with the general results
that many of Howarth’s claims were unjustified, but some impacts
were discovered. No species extinctions have been demonstrated to
have resulted from classical BC efforts to date.

H. In the 1990’s, two additional biological control journals appeared,
“Biological Control – Theory and Application in Pest Management”
(Academic Press) and “Biocontrol Science and Technology” (Carfax
Publishing). Additionally, “Entomophaga” changed its name to
“Biocontrol” in 1997.

 

 

Figs and their pollen carriers, fig-wasps have become very popular at least among biologists. Their relationship, in which we can see another extremely complicated relationship in nature, contains one of the hidden keys needed for solving the mysteries of co-evolution and the ecosystem.

This mutual relationship is believed to have begun about 90 million years ago, and approximately 750 varieties of figs (Ficus) now thrive. Amazingly, as a new kind of fig evolves, a fig-wasp corresponding to that new kind of fig appears. But a complicated co-evolution like this can be explained by Darwin’s theory of evolution, just as other happenings in nature can. His theory suggests that every creature evolves to leave the largest number of descendants in the next generation.

Plants, which have animals carry their pollen, offer the carriers a reward such as honey, or provide a carrier’s larva with a place to grow. Cabbage leaves rich in nutrition didn’t evolve to be a salad, but to be host food for larva of butterflies that carry cabbage pollen. Unfortunately, such larva become a horticulturist’s enemies.

The relationship between fig and fig-wasps in which an insect carries pollen and its larva eats the fruit is also seen in the cycad group and the yucca plant, a plant growing in arid areas in America. In this relationship, a contradictory relationship exists; that is, more pollen carriers are active more eggs are laid, and therefore more seeds are eaten even though the carriers help the plant bear fruit.

Fig flowers, which have the egg of a fig-wasp become a gall (an insect’s knot), food for larva, and fig flowers which don’t have an egg become seeds if they are pollinated. The number of female fig-wasps that develop into adults and fly out of the fig plant carrying pollen represents the number of carried pollen; that is, the adaptation rate of the male fig (the rate used to measure the size of the population of a certain genetic model in the next generation).

The number of seeds indicates the adaptation rate of a female fig. On the other hand, to become a host plant for male fig-wasps is fruitless for figs because male fig-wasps don’t have wings and can’t carry pollen. Therefore, figs don’t want to have too many male fig-wasps. Ideally, figs want to produce about the same number of female fig-wasps and seeds to create a balance between the number of female fig-wasps and fruit for themselves. On the other hand, fig-wasps want to lay as many eggs as possible to obtain the greatest possible benefit. Both the figs and fig-wasps co-exist by maintaining this subtly balanced relationship.

If the figs have a pollen carrier in all their flowers, no seeds will be left for the next generation. On the contrary, if figs reject pollen carriers too often, there won’t be enough pollen carried out for pollination. They both need to maintain this relationship. Some figs are heterosexual so male figs raise fig-wasps to carry pollen and female figs fruit seeds. Fig-wasps can’t mate in the female fig syconium, but the wasps can’t distinguish a male syconium from a female syconium. And the wasps that unfortunately come into a female syconium only help the fig pollinate.

Throughout the world, figs grow most abundantly in the forest of Ranbil on Borneo Island in Malaysia, and about 80 varieties of figs can be observed there. While we were studying there in 1998, there was a drought, and no fig flowers bloomed during that time. On that occasion, we made an interesting observation that fig-wasps came back right away as the flowers of the homosexual figs revived, but the wasps took two to three years to come back to the flowers of the heterosexual figs. Who knows when a change of weather in the tropical rainforest will create a new condition and give us clues to solve this mystery? I can’t take my eyes off the Ranbil forest.

 

 

 

Hard Chaparral

Chaparral covers about 8.5% of California and is the most characteristic natural vegetative type in the state. It reaches its fullest development in Southern California where it ranges in elevation between 1,000 and 5,000. Annual grasslands and coastal sage scrub occur along its lower limits and its upper limits border on mixed evergreen and coniferous forests. Various types of woodlands bisect hard chaparral in foothill areas and along canyon bottoms.

Chaparral bisected by grassland. The chaparral in the foreground shows a variety of plant species. Soft chaparral is the gray color on the distant hills, and hard chaparral is the dark green color.

The evergreen, stiffly branched shrubs of the true, or hard chaparral are mostly 3 – 10 feet tall. Leaves are small and leathery (sclerophyllous) with thick cuticles. Sometimes the leaves are so reduced as to appear needle-like e.g. Chamise (Adenostoma fasciculatum). These are adaptations to reduce evapotranspiration during the dry summer months. Stands of mature chaparral form a dense, almost impenetrable layer with little or no herbaceous understory.

Hard chaparral occurs in a mosaic reflecting fire history. A twenty-year cycle of fire maintains a community of Chamise. In communities with less frequent or more regular burns, Chamise gives way to Ceanothus, mountain mahogany, Sumac, Toyon, and Manzanita . Dwarfed oaks and drought-resistant, closed-cone pines also occur.

Adaptations to drought

Rain generally falls over the winter months in a few intense storms. The effective moisture is drastically reduced by rapid runoff, low moisture retention by soils, high rates of evaporation, and the protracted rainless period each year. To survive, chaparral plants must be adapted to 5 – 6 inches of rain per year and a drought of 5 – 6 months in duration. The dominant species are mostly spring active – they photosynthesize and grow in the spring when after moisture from the winter rains has penetrated far enough into the soil to become available to their roots.

As soil moisture supplies become limited, usually by late June, most chaparral plants enter a summer dormancy phase and operate at 5% of their wet season maximums. The plants are most susceptible to fire at this time.

By retaining their leaves, plants of the hard chaparral are physiologically ready to take advantage of a rare summer thundershower. Within minutes of the moisture being absorbed by the roots, the plants will be photosynthesizing. Their evergreenness makes them opportunists who can use soil moisture as soon as it becomes available. The leaves of the evergreen sclerophyll do not wilt so no part of the new water supply needs to be spent in rehydrating the leaves to maximize light absorption.

Succession and Aging

For the chaparral community, disturbance = diversity. It rapidly recovers from disturbance by fire, erosion or man. Chaparral succession is unique in that it succeeds itself rather than being preceded by other vegetative types. However, grasslands will become the dominant community if the previously chaparral-covered area burns many times within a short period. This reduces the chance of regrowth from burls or from seeds germinating, growing to maturity, and casting their seeds. Tje area is also more prone to invasion from non-native colonizing species.

When a chaparral area is prevented from undergoing burns (because of its proximity to a city for example) the accumulated biomass is so great that when the fire eventually occurs it is hot enough to destroy the underground plant structures that would otherwise guarantee the chaparral’s succession by more chaparral. These underground plant structures include buds on woody tap roots (lignotubers), burls, and underground rhizomes. However, the seeds of the chaparral shrubs remain viable after high-intensity burns and the area will eventually again become a stand of mature chaparral.

Immediately after a disturbance the herbs and forbs initially dominate because of their sheer numbers and showy flowers. Within 2 – 5 years the seedlings of chaparral plants and the shrubs resprouting from their crown roots or burls take over. Their more aggressive root systems exploit deeper water reserves and they will eventually shade out the forbs and grasses and replace them.

Productive growth is maintained in the canopy in mature unburned stands of chaparral. Common plants such as scrub oak, toyon, and holly leaf cherry all require a leaf litter that is at least 30 years old before they will germinate successfully. When the fire interval is short, for example between 10 – 15 years, these shrubs may be eliminated and the whole chaparral system replaced by grassland. Plant growth does not occur under the chaparral canopy due to lack of light, the activity of herbivores, and the fact that the seeds contained in the ground covering leaf litter are dormant.

 

Poisoning from Elderberry Juice — California

On August 26, 1983, eight people with acute gastrointestinal and neurologic symptoms were flown by helicopter to a Monterey, California, hospital. Earlier that day, they had attended a gathering for 25 persons of a religious/philosophic group in a remote area of Monterey County. Within 15 minutes after drinking refreshments, 11 persons began to have nausea and vomiting. The eight persons most ill reported nausea, vomiting, abdominal cramps, and weakness. Some also complained of dizziness and numbness; one was stuporous and was hospitalized.

Arterial blood gases were normal for all eight, as were serum cyanide levels (reported later). The San Francisco Bay Area Regional Poison Control Center was promptly consulted regarding treatment for possible cyanide poisoning, but specific treatment was not given because 4 hours had elapsed since exposure, blood gases were normal, and the patients were stable. All recovered quickly, including the patient hospitalized overnight.

Investigation by the Monterey County Health Department revealed that staff at the religious center had gathered local, wild elderberries 2 days before the outbreak and had prepared juice from them the next day. Bunches of berries were crushed with their leaves and branches in a stainless-steel press.

Apple juice, water, and sugar were added, and the mixture was stored overnight. The drink was served the next day in a stainless-steel pot to the group of 25 persons. The severity of illness correlated with the amount of elderberry juice consumed; those who drank only tea remained well. The hospitalized person had consumed five glasses of the juice; the others, much less.

Editorial Note

Editorial Note: The indigenous elder tree of the western United States, Sambucus mexicana, can grow to 30 feet and produces small (1/4-inch), globular, nearly black berries that can be covered with a white bloom at maturity. The berries are juicy and edible when mature. The cooked berries are commonly eaten in pies and jams, and berry juice can be fermented into wine.

The fresh leaves, flowers, bark, young buds, and roots contain a bitter alkaloid and also a glucoside that, under certain conditions, can produce hydrocyanic acid. The amount of acid produced is usually greatest in young leaves. There may be other toxic constituents in this plant. The root is probably the most poisonous and may be responsible for occasional pig deaths; cattle and sheep have died after eating leaves and young shoots.

Although a review of the medical literature revealed no other reports of elderberry juice poisoning in the past 20 years, there are older, anecdotal reports of poisoning in children from the related elder, S. canadensis. The religious center staff has been advised that, while elderberries may be safe to consume, particularly if cooked (uncooked berries may produce nausea), leaves and stems should not be crushed when making juice.

Reported in California Morbidity (February 24, 1984) by S Kunitz, MD, RJ Melton, MD, T Updyke, Monterey County Health Dept, D Breedlove, PhD, California Academy of Sciences, San Francisco, SB Werner, MD, California State Dept of Health Svcs. Bibliography Casarett LJ, Doull J, eds. Toxicology: the basic science of poisons. New York: Macmillan Publishing Company, 1975. Kingsbury JM. Poisonous plants in the United States and Canada. Englewood Cliffs, New Jersey: Prentice-Hall, 1964. Millspaugh CF. American medicinal plants. New York: Dover Publications, Inc. Muenscher WC. Poisonous plants of the United States. New York: Macmillan Company, 1951. Osol A, Farrar GE. The Dispensatory of the United States of America. 25th ed. Philadelphia: JB Lippincott Company, 1955. Pammel LH. A manual of poisonous plants. Cedar Rapids, Iowa: The Torch Press, 1911.

Marshmallows come from the sweet sap of the ‘Mallow’ Plant that grows in salty marshes near large bodies of water and grows 2 to 4 feet high.

Hence! MARSH + MALLOW = MARSHMALLOW

The ancient Egyptians used the mallow root for making their candied delicacies for their Gods, Nobility, and Pharaohs over 2000 years ago. Since it was a crime for anyone else to eat this sugar-like treat, children looked to honey and figs to cure their sweet tooth.

Egyptian marshmallows were a mixture of Mallow sap, honey, and grains and baked into cakes. The Romans and the Greeks loved the Mallow Plant; they believed that brewed mixtures of the Mallow sap cured soar throats and pains. The sugar mixture was found in Hippocrates’s medical treatments. During the 15th and 16th centuries, marshmallow liquids were given as treatments for toothaches, coughs sore throats indigestion, and diarrhea It was even believed to have been used as a love potion at this time.

It was the French during the 1800s that changed the use of the mallow plant from mainly medicinal to more of a candy consumed by adults. French shop owners discovered that cooking and whipping marshmallow sap with egg whites and corn syrup created an easily moldable substance. This is where the marshmallow as we know it today was born!

In the 1900’s marshmallows were being sold as penny candies in tiny tins. It was at this time that the Boyer Brothers, interested in growing their neighborhood business, started experimenting with marshmallow creme and tried to cover it in chocolate. After many unsuccessful attempts, their mother Emily suggested they put it in a paper cup, using the only thing that they had available- a paper cupcake holder. They tried once more, and… Success! The Mallo Cup was born!

“Do they still make Mallo Cups?” The answer to this is yes and will always be yes! Boyer Candy Company has been proudly making delicious nostalgic candy since the 1930s and has built up a reputation and history just as long and rich as the marshmallow history above! Mallo Cups were the very first cup candy produced in the United States and are still adored by people of all ages. The delicious combination of marshmallow and chocolate has made this nostalgic candy a favorite among all candy lovers.

Mallo Cups have given Boyer Candy Company its place in the wonderful marshmallow history timeline. This delicious and unique candy has been a popular part of candy history since its introduction many, many years ago and remains one of the most popular American-made candies still produced. Some might call Mallo Cups a retro candy, but something this delicious is timeless. Find Mallo Cups and more at BoyerCandies.com today.

Trees help to break down barren rocks into soil, but how does that work exactly? It turns out that tiny fungi living on the trees’ roots do most of the heavy work.

The fungi first bend the structure of certain minerals, weaken their crystals, and then remove any useful chemical elements to pass on to their host tree. During the process, the rocks change their chemistry, lose their strength, and in the long run, become soil.

These hard-working fungi are called mycorrhiza and cover the roots of trees like gloves. They are extremely small and thin, but they are everywhere: ‘it is estimated that every kilogram of soil contains at least 200 km of fungi strands,’ says Dr Steeve Bonneville, from the University of Leeds.

Bonneville explains: ‘Mycorrhiza has a perfect business relationship with plants and especially trees.’ They help the plant to get nutrients from the soil and in return, they receive part of the carbon produced during photosynthesis.

About 90 percent of tree roots in boreal forests have this symbiotic association with mycorrhiza.

Mycorrhiza plays a major role in soil formation, but how do they do it? ‘We created the first experiment that closely copies a natural system to find out how mycorrhiza helps to break down minerals,’ says Professor Liane G. Benning, the Leeds principal investigator of the project.

Together with colleagues at Sheffield, the team planted a Scots pine seedling with the fungi Paxillus involutus, a mycorrhiza species. ‘This is a very common tree-fungi association that occurs naturally in boreal forests,’ says Bonneville. The tree and fungi were allowed to grow together for about 10 weeks and were then placed in a transparent pot with flakes of biotite, a common rock-forming mineral rich in potassium, iron, and magnesium.

The seedling’s roots became covered with fungi, which soon attached to the biotite. After three months, the scientists removed the biotite from the experiment and sampled the crystal along a single strand of fungi-covered root from the tip, middle, and close to the root.

Bend first, steal later

‘The first change we observed in the biotite, at the tip of the mycorrhiza, was mechanical stress,’ says Benning. The fungi can apply pressure onto the minerals that can be as high as the pressure in an average car tyre. This pressure value is ‘very high’, for a tiny organism, but unsurprising to Bonneville: ‘These fungi evolved to penetrate minerals and rocks and some species are capable of even higher pressures.’

As a consequence of the pressure at the tip, the biotite starts to bend and lose its strength. ‘Once the crystal structure is weakened, the chemical changes start,’ explains Benning. The mycorrhiza then proceeds to remove the potassium and other useful nutrients from the biotite, passing them on to the roots and ultimately the tree. Without potassium, the biotite breaks down into vermiculite and ferrihydrate, two minerals common in soils.

The mechanism – bend the structure first, steal nutrients later – is an efficient way for the fungi to break down minerals and at the same time gather essential nutrients for its host tree, write the authors of the report, published in July’s edition of the journal Geology.

‘This is a significant advance on previous simplistic ideas of mineral breakdown,’ says Benning.

S. Bonneville, M.M. Smits, A. Brown, J. Harrington, J.R. Leake, R. Brydson and L.G. Benning. Plant-driven fungal weathering: Early stages of mineral alteration at the nanometer scale Geology July 2009, v. 37, p. 615-618, doi:10.1130/G25699A.1