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Glossary: Co-Cz

Cobnut
See: Corylus avellana.
Coca
See: Erythroxylon coca.
Cochliobolus
See: Helminthosporium.
Cocoa
See: Theobroma cacao.
Coconut
See: Cocos nucifera.
Cocos nucifera
The coconut palm. An extraordinarily useful palm that provides food, drink, fibre, timber, thatch, mats, fuel, and drinking cups.
This palm is also the source of copra, the dried endosperm, which was the major source of vegetable oil until the mid-twentieth century, and the major cash crop on innumerable tropical islands. This oil was used mainly for the manufacture of soap, and the market declined with the development of soapless detergents and other oil crops, such as soya, canola, and oil palm.
The species is usually divided into tall palms and dwarf palms. It is thought that the former represent the wild type, and the latter are the result of very ancient domestication that brought more numerous nuts closer to the ground and easier to open.
There is scope for amateur breeders to cross-pollinate the two types to produce hybrid palms with an increased yield and, in the Caribbean, resistance to lethal yellowing disease.
The coconut is of considerable anthropological interest because it provided a source of both drinking water and Vitamin C on long ocean voyages. Austronesian people were sailing across oceans several millennnia before the Chinese developed ocean-going ships in the fourteenth century, or the Europeans, in the fifteenth century. This ocean travel permitted the colonisation of uninhabited ocean islands, and the spread of the Austronesian family of languages to Madagascar in the West, Easter Island in the East, Hawaii in the North, and New Zealand in the South.
Coconuts spread naturally, by floating on sea water, to the east coast of Africa, and the islands of the Western Pacific. However, they were unable to reach the west coasts of America, or the Atlantic. They were taken to both areas by European sailors in the sixteenth century. The Portuguese took them from East Africa to West Africa and the Caribbean. The Spanish took them across the Pacific to the New World.
The palms of the west Pacific were in epidemiological contact with the centre of origin, and were resistant to various coconut diseases. The palms of East Africa, however, had been separated epidemiologically from the centre of origin for millennia, and they are susceptible to diseases such as Cadang-Cadang in the Philippines, and Lethal Yellowing in the Caribbean.
Both diseases can be controlled by planting hybrids that are crosses between the Pacific Tall and the dwarf palms.
Coco-yam
See: Xanthosoma sagittifolium and Colocasia esculenta.
Codling moth
See: Carpocapsa pomonella.
Coffea arabica
Arabica coffee. This is the main coffee of commerce. It is an autogamous allotetraploid, (2n = 44) believed to have been derived from an infertile cross between the two wild diploid, Coffea canephora and Coffea eugenioides (2n = 22), which subsequently doubled its chromosome number to become a fertile tetraploid.
First cultivated in Ethiopia, it was taken to Arabia Felix (Southern Yemen) where the famous Mocha variety was grown. The Dutch then took it to Ceylon (Sri Lanka) and Indonesia. Seed was then taken to Amsterdam, and one tree was given to the King of France who sent seed to Martinique. All the coffee of the New World was derived from this seed and was a pure line. All the pests and diseases had been left behind in the Old World, and Latin America soon became the principle coffee producing area, with Brazil in the lead.
As a result of a horizontal resistance program, Ethiopia now has coffee cultivars with sufficient resistance to control all the major pests and diseases, including coffee berry disease, and it is the only country that can produce this resistant coffee that does not need any crop protection chemicals.
In countries where the ripe berries are picked by hand, the ‘wet method’ of processing is used. The coffee is pulped, graded, and fermented to produce so-called parchment coffee, which is then dried in the sun. It is then hulled to remove the parchment and silver skin. This produces a mild coffee that will tolerate a light roast.
With the ‘dry method’, whole cherries are dried in the sun and then milled. This produces a hard coffee which must be given a dark roast.
Possibly the most promising approach to coffee breeding is to re‑create the allotetraploid from the two wild diploids. But this is not recommended for amateur breeders.
See also: Hemileia vastatrix.
Coffea canephora
Robusta coffee. Less desirable than C. arabica, it is suited to a much wetter climate, and is in demand for the manufacture of instant coffee. Believed to be one of the diploid parents of the allotetraploid Coffea arabica.
Coffea eugenioides
A wild diploid coffee of eastern Africa, of no commercial value, but it is believed to be a parent of the allotetraploid Coffea arabica. If an attempt were made to re-create Coffea arabica, this species would become scientifically important.
Coffee
See: Coffea arabica, Coffea canephora, and Coffea eugenioides.
Coffee berry disease (CBD)
See: Colletotrichum coffeanum.
Coffee leaf rust
See: Hemileia vastatrix.
Coix lachryma-jobi
Adlay, or Job’s tears. Coix is a genus of monoecious grasses. Several species are of ancient cultivation as cereals in S.E. Asia, China, and Japan. A crop of considerable potential for amateur breeders.
Cola
See: Cola spp.
Cola spp.
Several species of this West African genus provide kola nuts that are rich in caffeine and are chewed as a stimulant. In ancient times, the kola trade defined the camel caravan routes from Sokatoo and Timbuctoo to the Mediterranean. There is now no international trade in kola nuts, and modern cola drinks contain no true kola.
Colchicine
A drug extracted from meadow saffron and used to induce polyploidy in plants.
Colletotrichum coffeanum
This is quite the most serious disease of coffee, and it is caused by the fungus Colletotrichum coffeanum. At present it is confined to eastern Africa.
The fungus resides in the bark and parasitises the berries only. In a susceptible tree, there is a total loss of all berries several months before harvest, and this represents the minimum level of horizontal resistance.
In resistant trees selected recently in Ethiopia, there is no loss of berries, and this represents the maximum level of horizontal resistance. In other countries where the disease occurs, it is controlled with fungicides.
Colocasia esculenta
This vegetatively propagated root crop is known variously as taro, dasheen, or coco yam. It is one of the aroids, and was the basis of the agriculture in Papua New Guinea, which is amongst the oldest in the world, dating from about 7000BC.
It is a labour-intensive crop, and it became only a minor staple, which lacked the potential of a major staple, capable of supporting the growth of cities and the development of a sophisticated civilisation. There is some room for improvement by amateur breeders, mainly by selection within existing cultivar.
Colorado potato beetle
See: Leptinotarsa decemlineata.
Combine harvesting
Harvesting grain with a self-propelled machine that both cuts and threshes the crop. Combine harvesters usually have a storage bin that can be discharged into a truck moving alongside, while the harvesting continues without a break. Many machines also have a system of chopping the straw and discharging it on to the ground, often in windrows suitable for burning to control pests and diseases. Combine harvesters are used on most temperate cereals, some pulses, and crops such as mustard and canola.
Complexity theory
Modern complexity theory divides all systems into the two categories of linear and non-linear systems.
The ‘hard’ sciences, such as chemistry, physics, and astronomy, are based on linear systems, in which the parameters are fixed, are easily measured, and the outcomes easily predicted. The ‘soft’ sciences, such as all the life sciences, are based on non-linear systems, in which the parameters are liable to change, are difficult to measure, and the outcomes difficult to predict.
For example, the solar system is a linear system, and we can predict the phases of the moon, and the tides, with great accuracy for centuries ahead. But the weather is a non-linear system and even short-term weather forecasts can be unreliable.
An essential feature of non-linear systems is the property of self-organisation and this is the basis of the concept of self-organising crop improvement.
See also: General systems theory.
Compositae
The botanical family that includes lettuce, sunflower, Jerusalem artichoke, pyrethrum, safflower, chrysanthemums, and daisies. It is characterised by an inflorescence of many small florets in a single disk, usually surrounded by the petals of the outermost florets.
Compost
Compost is organic matter that has been broken down into humus, mainly by aerobic bacterial decomposition. It is an important resource for organic farmers, as a soil amendment that adds organic matter to the soil and provides high-quality nutrition to their crops.
Source materials for compost can include animal manure and bedding, crop stalks and hulls, food waste, etc. Composting can be done in-field, in compost piles or in windrows.
Comprehensive horizontal resistance
See: horizontal resistance.
Congo pea
See: Cajanus cajan.
Conidia
The asexual produced, microscopic spores of a fungus that permit both vegetative propagation and a rapid and widespread dissemination. Conidia are usually produced in very large numbers, and these fungi are rstrategists capable of a rapid and large population explosion.
Conidiophore
The microscopic stalk of a fungus that bears asexual spores called conidia.
Conifer
Any tree of the order Coniferales, usually bearing cones and having needle-like leaves. Known as the Gymnosperms, they include pines, cedars, yew, and redwood.
Conservation
See: Genetic conservation.
Consultative Group for International Agricultural Research
The Consultative Group on International Agricultural Research, is located in Washington, DC.
This is the body that allocates funds, amounting to several hundred million dollars annually, to the International Research Centres.
Consumers
1. A term in economics: purchasers of market produce. Consumers are a significant factor in the self-organising food production system because they determine which items sell best. For this reason, they are also a significant factor in self-organising crop improvement.
2. A term in evolution: one of the three primary groups of living organism, the others being producers and reducers. Consumers obtain their nutrients from other living organisms, and they include all herbivores, carnivores, omnivores, and parasites.
Contamination
From the point of view of plant breeders, contamination refers to unwanted foreign pollen that can accidentally enter the recurrent mass selection from outside, and introduce undesirable characteristics such as susceptibility.
Contamination can also occur in cultures of plant pathogens.
A distinction is also made between contaminated seed and infected seed. The former has parasites on the outside and can be decontaminated with surface seed dressings. The latter has internal parasites, which can be eliminated only by hot water treatment, or by systemic chemicals.
Continuity
See: Continuous epidemic.
Continuous distribution
Quantitative data that reveal a continuous spectrum of values between a minimum and a maximum. See also: Normal distribution.
Continuous epidemic
In epidemiology, a continuous epidemic is one in which the parasitism never stops. This is sometimes called endemic disease. The epidemiological significance of continuity is that the parasite does not need to find a means of survival in the absence of a host. (See also: discontinuity).
Continuous pathosystem
A pathosystem in which host tissue is continuously available, and the parasitism continues indefinitely, without a break. Continuous pathosystems occur typically in evergreen, perennial hosts. Autoinfection is of primary importance in continuous pathosystems.
Vertical resistance has no survival value in continuous pathosystems, and it is not found in a crop species that is derived from a continuous wild pathosystem.
See also: discontinuous pathosystem.
Continuous variation
A term sometimes used for quantitative variation, in which there is every degree of difference between two extremes. Thus, horizontal resistance shows continuous variation between its minimum and maximum levels. See also: discontinuous variation.
Contour ploughing
A system of ploughing in which the furrows follow the land contours in order to minimise soil erosion.
Copper
Copper is an important plant nutrient. It is an immobile element. Deficiency symptoms show first in the young leaves and shoots and result in general growth failure. Various copper compounds are used as fungicides.
Copper sulphate
Copper sulphate is obtained by dissolving metallic copper in sulphuric acid to produce a blue solution that crystallises into blue crystals known as ‘blue stone’. It is a constituent of Bordeaux mixture, which is made by adding newly slaked lime to a solution of copper sulphate.
Copra
See: Cocos nucifera.
The legal protection of intellectual property. Most countries now have a system of granting copyrights to plant breeders for new cultivar. The breeders are then entitled to royalties on all seed sales of their cultivars. This system of reward is of special interest to amateur plant breeders, and to plant breeders associations. New cultivars with high levels of horizontal resistance can be accurately identified with DNA ‘finger printing’.
Coriandrum sativum
An annual herb called coriander, and widely used since ancient times as a seasoning.
Corchorus spp.
Jute. This fibre crop is cultivated mainly in India. It provides considerable scope for amateur breeders, who should remember, however, that plastic fibres have largely replaced the natural plant bast fibres.
Corm
An underground storage organ of a monocotyledon consisting of a solid swollen stem. The next season’s corm usually forms on top of the old one. Not to be confused with a bulb. Crocuses have corms, and tulips and onions have bulbs.
Corn
Technically, any small cereal grain. However, the use of this term is usually confined to the most important cereal within a region. Thus, in the corn belt of the USA, the term refers to maize. Corn in Britain is wheat. In Scotland, it is oats.
Corolla
A whorl, or whorls, of petals that forms the inner envelope of a flower. The petals may be either free or joined, and they are often brightly coloured to attract pollinating insects.
Corporate plant breeding
Plant breeding undertaken by large corporations, usually chemical manufacturers. Because their motives are profit-driven, they have a vested interest in promoting the use of chemical pesticides rather than horizontal resistance. Consequently, they can be expected to produce new cultivars that have excellent yield, quality, and agronomic suitability, but that also have low levels of resistance.
Corporate plant breeding is also involved in genetic engineering and the production of cultivars that have special properties, such as resistance to herbicides.
Corylus avelana
The hazel nut, cobnut, or filbert. This species shows considerable diversity and some taxonomists have suggested additional specific names. Not much scope for amateur breeders.
Corynebacterium
A genus of plant pathogenic, gram-positive bacteria that cause disease in tomato, potato, and various ornamentals.
Cosmopolitan cultivars
Cultivars that have a wide geographical and environmental range.
Cotton
See: Gossypium spp.
Cotyledon
The first leaves produced by germinating seeds are called cotyledons. All flowering plants (Angiosperms) are divided in those that produce either one or two cotyledons at the time of seed germination.
Monocotyledons are plants that produce a single cotyledon, and they are often called the narrow-leaved plants. Among cultivated plants, they include all the grasses, cereals, and sugarcane, crops of the onion family, bananas, pineapples, palms, and ginger.
Dicotyledons are plants that produce two cotyledons, and they are often called the broad-leaved plants. Seeds of dicotyledons can be split into two halves (e.g., split peas). Among cultivated plants, they include all the peas and beans, most of the temperate fruits and nuts, crops of the cabbage, cucumber, and potato families, cotton, rubber, tea, coffee, cocoa, cassava, sweet potato, and many vegetables and herbs.
Covered smuts
The smut fungi are a group within the Basidiomycetes which cause diseases mainly in cereals and grasses. The covered smuts (c.f., loose smuts) are so-called because they form a black spore mass inside the seed, and these spores are released when the seed coat breaks. In cereal crops, this produces contaminated seed, as opposed to infected seed, and the disease can be easily controlled with a fungicidal seed dressing.
There is a covered smut of barley (Ustilago hordei), oats (Ustilago kolleri), and sorghum (Sphaceolotheca sorghi). The covered smuts of wheat are usually called bunt, or stinking smut, and are caused by Tilletia caries, T. foetida, and T. contraversa.
Cowpea
See: Vigna unguiculata.
Cranberry
See: Vaccinium spp.
Crescentia cujete
The calabash, which is native to tropical America. The hard fruits are used as containers and musical instruments (maracas).
Cress
See: Lepidium sativum.
Crinipellis perniciosa
The fungus which causes ‘witches’ broom’ disease of cocoa.
Crocus sativa
Saffron. A much prized spice and yellow colouring obtained from the stigmas of the Crocus. Saffron is the basis of French bouillabaisse, Spanish paella, English saffron buns, Jewish gilderne, Russian challah, Indian zaffrani chawal, and Persian sholezard.
Saffron is also the most expensive spice of them all, because the stigmas of a crocus flower are the most labour-intensive of all crops to harvest.
The wild progenitors of the saffron crocus are extinct, and this is an indication of its antiquity. Like garlic, the cultivated crocus does not set seed, and, it can be propagated only by corms. Multiplication of the crop is a very slow process because only two or three new corms are formed each year at the base of the old corm.
It is not known how many clones exist but it is quite clear that all of them are ancient, and that they have been cultivated for millennia without any use of crop protection chemicals.
Not recommended for amateur breeders.
Cronartium ribicola
White pine blister rust. This is a heteroecious rust of five-needled pines (Pinus spp.), and its summer host is Ribes spp. It was apparently introduced to North America at the turn of the nineteenth century, where it largely destroyed the white pine forests.
It is thought (but not proved) that this introduction was an allopatric pathotype native to Eurasia, and that a local, North American pathotype had been present all the time. The two pathotypes would have become isolated from each other some sixty five million years ago with the separation of the continents. This would explain why an apparently functioning gene-for-gene relationship exists in the North American pathosystem of the Eurasian pathotype.
Apparently, the same gene-for-gene relationship exists in both geographical areas and, if confirmed, this would provide a useful indication of the evolutionary age of gene-for-gene relationships. The North American white pines would have had adequate horizontal resistance to their own horizontal pathotype, but not to the allopatric pathotype.
Surviving white pines are likely to be resistant, and their selection and propagation would form an excellent project for a plant breeding club in the forestry department of a university.
Crop
Any population of plants that is cultivated by a farmer. Crops are often defined by their ultimate purpose. Thus, cash crop, subsistence crop, food crop, fodder crop, etc.
Crop architecture
The shape of crop plants and, hence, the nature of the crop itself.
For example, the bean varieties of one species may have either the determinate habit, or they may be climbing vines. The latter are useful for climbing up maize plants in mixed cropping, while the former are more suitable as a pure stand, and for mechanical cultivation and harvesting.
The miracle wheats and rices of the Green Revolution are dwarf varieties that can tolerate high rates of nitrogenous fertiliser without lodging.
Soybeans became an important commercial crop only after types suitable for combine harvesting had been developed.
Some crops, such as potatoes, can be densely planted in order to cover the ground completely, in order to control weeds.
Crop husbandry
The practice and science of the cultivation of crops.
Crop loss due to parasites
The crop losses caused by parasites are usually subdivided into pre-harvest and post-harvest losses, also known as field losses and store losses, respectively.
Pre-harvest losses are controlled primarily by breeding the host for resistance, and by the use of crop protection chemicals. Other methods include rotation, to reduce the incidence of soil-borne parasites, and the burning of crop residues.
Post-harvest losses are controlled mainly by keeping the product dry, and by depriving the parasites of oxygen.
Crop parasites
Any organism in which an individual spends a major proportion of its life cycle inhabiting and obtaining nutrients from one host individual.
The term includes parasitic Angiosperms, insects, mites, nematodes, fungi, bacteria, phytoplasmas, viruses, and viroids.
Entomologists normally handle the insects and mites, while plant pathologists usually handle all the other categories.
Crop pathosystem
An agricultural plant pathosystem in which people have changed the natural mechanisms of self-organisation. The host, the parasite, and the environment have all been altered by the activities of agriculture.
A crop pathosystem is normally characterised by genetic uniformity, and genetic inflexibility.
If it is derived from a continuous wild pathosystem, it will not have any vertical resistances; if derived from a discontinuous wild pathosystem, it may have vertical resistances.
Crop protection
The combined disciplines of entomology, plant pathology, and plant breeding, aimed at jointly and cooperatively reducing crop losses resulting from both parasites and weeds.
Most modern crop protection depends very heavily on crop protection chemicals, and the chief goal of amateur plant breeders is to reduce human dependence on chemicals by breeding crops for horizontal resistance.
Crop protection chemicals
In the wide sense, this term means any chemical used to control crop parasites or weeds. The former are mainly insecticides and fungicides, while the latter are herbicides. In any discussion of crop parasites, however, the term is usually used to exclude herbicides.
Crop protection, natural
As an alternative to synthetic crop protection chemicals, farmers and gardeners may use more natural alternatives such as rotenone, pyrethrin and Bordeaux mixture.
However, organic growers aim to promote a balanced local ecology that minimizes the impact of any one pest or disease, reducing the likelihood of needing to apply crop protection.
See also: integrated pest management.
Crop rotation
The cultivation of a succession of different species of crop on the same land. The main purpose of rotation is to reduce or prevent the build up of large populations of parasites, particularly soil-borne parasites. Other functions include maintaining high levels of soil fertility.
Crop science
The combined disciplines of agronomy, horticulture, plant pathology, entomology, plant breeding, and plant physiology. Agricultural engineering and agricultural economics are sometimes included in this term.
Crop vulnerability
A crop is vulnerable if it is susceptible to a foreign parasite which is absent from the area in question. If the foreign parasite arrives in that area, the susceptibility is revealed, and the vulnerability is manifested. Potential damage then becomes actual damage.
Some crop vulnerabilties are slight and unimportant. Others can be extreme, and the resulting damage can have major social and economic consequences. Thus the potato crops of Europe before 1845 were highly vulnerable to the blight fungus Phytophthora infestans. Note that a crop is vulnerable only if the parasite in question has epidemiological competence in the area concerned.
Cross
Short for cross-pollination.
Crossing generation
In recurrent mass selection, a plant breeding cycle may involve several generations. The crossing generation is the one in which cross-pollination occurs.
See also: single seed descent; late selection; family selection.
Cross-pollination
Fertilisation with pollen coming from a different plant. When cross-pollination involves two genetically different plants, it leads to heterozygosity.
See also: allogamy, outbreeder, self-pollination.
Crotalaria juncea
Sunn hemp, which is cultivated throughout the tropics as a fast-growing green manure. It is also widely used in India as a fibre for sacking and cords, but it is inferior to true hemp (Cannabis).
Cryptic error
The term originally used by J.E. Vanderplank to describe inter-plot interference or parasite interference.
Cucumber
See: Cucumis sativus.
Cucumis anguria
The West Indian gherkin. These fruits are used mainly in pickles, but they should not be mistaken for the more common gherkin which is only a small cucumber.
Cucumis melo
Melon. This highly variable species consists of four basic types, which interbreed freely.
The ‘Cantaloupe’ melon is the most commonly cultivated and is characterised by a think, rough rind.
The ‘Honey Dew’ melon, with ivory skin and green flesh, is also widely grown, and is in the group known as the winter or ‘Casaba’ melons.
‘Musk melon’ is popular in the United States and has a smooth skin and shallow ribs.
Melons are open-pollinated. Most musk melons are andromonoecious, while Cantaloupes are usually monoecious. A good crop for amateur breeders.
Cucumis sativus
Cucumbers and gherkins. This species originated in India.
There is a wide range of cultivars. The so-called ‘English’ cucumber has long fruits that are used mainly in salads and sandwiches. Pickling cucumbers have small fruits and are pickled as gherkins. The ‘Sikkim’ cucumber of India has reddish-brown fruits.
All members of this species are monoecious, annual herbs, and some are parthenocarpic. There is considerable scope for recurrent mass selection by amateur breeders.
Cucurbita maxima
The pumpkin, also known as the winter squash. This species has extremely large fruit that is widely used for making Jack-o’-lanterns at Hallowe’en. The fruit and seeds are edible. The species is monoecious and can be a fun crop for amateur breeders.
Cucurbita pepo
The vegetable marrow, or squash, which originated in Central America.
This species formed one of the kingpins of ancient Aztec farming, in which maize, beans, and squash were grown in a system of mixed cropping that both supplied a remarkably complete diet, and has proved remarkably sustainable. However, this system is quite labour-intensive.
This species is a very variable, monoecious, annual herb. Most modern breeding has involved pedigree breeding with transfers of vertical resistance genes, and the production of hybrid varieties.
In Europe, the seed is used as a source of high quality oil, and a mutant, lacking the heavy seed coat, produces seed containing 45-50% oil.
There is scope of recurrent mass selection by amateur breeders.
Cucurbita spp.
This genus originated in the area of Mexico-Guatemala and has twenty-six species, of which five are cultivated.
The principle cultivated species is Cucurbita pepo, and is described separately. In addition C. moschata, C. maxima, C. ficifolia, and C. mixta provide winter squash in Central America and parts of South America.
They provide scope for recurrent mass selection by local plant breeders associations.
Cucurbitaceae
The botanical family that includes cucumbers, pumpkins, melons, etc. Most species are open-pollinated, and many are monoecious, and provide scope for amateur plant breeders.
The main cultivated species are the wax or white gourd (Benincasa hispida) used as a vegetable in S.E. Asia; the water melon (Citrullus lanatus); the west Indian gherkin (Cucumis anguria); the melon (Cucumis melo); the cucumbers and gherkins (Cucumis sativus); the pumpkin (Cucurbita spp.); the marrow (Cucurbita pepo); the bottle gourd (Lagenaria siceraria); the loofah (Luffa spp.); the bitter gourd (Momordica charantia); and the choyote or christophine (Sechium edule).
Cucurbits
Members of the botanical family Cucurbitaceae.
Cultigen
A plant species or variety that is known only in cultivation. See also: cultivar; extinct wild progenitors.
Cultivar
A cultivated variety, which has originated and persisted under cultivation, as opposed to a botanical variety, which is a component of a wild species.
Cultivar names should be written with capital letters and enclosed in single quotation marks (e.g., ‘Russet Burbank’), but some authors prefer to use italics without quotation marks.
A cultivar is usually a pure line, a clones, or a hybrid variety, and it is genetically uniform, and genetically inflexible. A cultivar consequently cannot respond to selection pressures during cultivation.
See also: ecotype, agro-ecotype, landrace, micro-evolution.
Cultivation
The various processes of growing a crop.
Culture
In an agricultural context, this word means the growing of either a crop, or a micro-organism.
Cuminum cyminum
Cumin. A member of the botanical family Umbelliferae, cultivated in S.E. Europe, North Africa, India, and China. The seeds are used for flavouring curry powder and other mixed spices.
Curcuma domestica
Turmeric. This genus is native to S.E. Asia and is a member of the ginger family, Zingiberaceae. The rhizomes provide a yellow dye, and a flavouring essential to all curry powders.
It is one of those crops in which true seeds are not produced, and its ancient clones are a useful example of the durability of horizontal resistance. The wild progenitors are extinct.
Various clones exist in India, usually named after their home district, and varying in their suitability as a spice or a dye.
Currants
In a horticultural sense, currants are species of Ribes, and are known as red, white, and black currants. The black currant is a useful source of Vitamin C. However, the currants used in currant buns, and other cooking, are a special variety of dried grape called ‘Corinth’, and the term ‘currant’ is a corruption of this name.
Curry powder
In India, any good cooks make their own curry powders, and there are as many recipes as there are good cooks.
Most curry powders contain about 25% turmeric (Cucurma domestica), 25% coriander (Coriandrum sativum) seeds, and various amounts of cumin (Cuminum cyminum) seeds, cardamoms (Elettaria cardomomum), fenugreek (Trigonella foenum-graecum) seeds, chillies (Capsicum annum), ginger (Zingerber officinale), black pepper (Piper nigrum), and dill (Anethum graveolens) seeds.
Cuscuta spp.
Dodder, also known as strangle-weed, hellbind, hailweed, and devil’s hair. These species belong to a mono-generic family, the Cuscutaceae, in which all members are parasitic on other plants.
Dodder consists mainly of yellow-red, slender, vine-like stems with vestigial leaves, and the plants lack chlorophyll entirely. Dodder can occasionally be an agricultural nuisance.
Dodder is used in research to transmit viruses from one host plant to another.
Cuticle
The outermost layer of the epidermis. A thick cuticle is often a mechanism of resistance.
Cuttings
Pieces of stem that are planted so that they may form roots and, eventually, new plants by vegetative propagation. All the cuttings originating from a single parent constitute a clones. The best method of rooting cuttings is in a mist-propagator.
Cyamopsis tetragonolobus
The cluster bean, or guar, is a member of the Leguminosae. Its wild progenitors are extinct but it is thought to have been a native of Africa, taken at an early date to S.E. Asia, where it now has many uses. It is also grown as a cash crop in Texas and Oklahoma. Some scope for amateur breeders in S.E. Asia.
Cyanide
Any of the extremely poisonous salts of hydrocyanic acid, particularly potassium cyanide. It was used as an insecticide before the discovery of DDT and later synthetic insecticides.
Cyano-bacteria
Also called the blue-green algae, these prokaryote organisms contain photosynthesising pigments. They were apparently the first producers to appear on the evolutionary scene, and they have survived until the present.
Cyclone separator
Equipment for separating dust or other fine particles from air. The dusty air is spun as a cyclone inside a hollow cone. Being heavy, the solid particles are thrown against the sides of the cone by centrifugal force, and they sink to the calm air at the bottom of the cone. The clean air escapes through the top of the separator.
This equipment is usually quite large, and handles large quantities of dusty air being extracted from a factory or mill. However, miniature versions are made for collecting relatively large quantities of microscopic pollen grains, rust spores, etc.
Cynara scolymus
The globe artichoke. This Mediterranean crop is a perennial thistle and is vegetatively propagated, because true seedlings are very variable.
Cynodon dactylon
Star grass, also known as Bermuda grass or Bahama grass. One of the most widely dispersed grasses in the tropics and subtropics, extending even to S.W. England.
While it can be a serious weed, with fast-growing rhizomes and runners, it can be useful as both a pasture grass and a turf grass. It is usually propagated vegetatively, but some forms can be sown by seed.
Non-rhizomatous, high-yielding strains are known and are very useful. There is scope for amateur breeders.
Cyphomndra betacea
The tree tomato. This tree is not a true tomato but it belongs to the same family (Solanaceae) and it has fruits that taste like tomatoes.
Cyrtosperma chamissonis
Giant taro. This plant is a huge herb growing up to four metres in height, grown for its tubers that take several years to mature, with a record of a sixty kilogram tuber in a plant ten years old. It is propagated vegetatively and it is usually grown in swamps.
Cytoplasm
The contents of a cell that are enclosed by the membrane, but excluding the nucleus.