GLOSSARY

ALKALOIDS

A diverse group of secondary metabolites, which contain a nitrogen-bearing molecule. They are often poisonous and are widely used in medicine and other fields. A well-known drug produced from alkaloids is vincristine from the Madagascar Periwinkle (Catharanthus roseus). Atropine from deadly nightshade (Atropa belladonna) is used as a pain reliever amongst other things. Their function in the plant is not well understood.

ANTHOCYANINS

Glycoside pigments occurring in the sap of stems, leaves, flowers and fruits and giving rise to the blue, purple or red colour found in these parts. Plants high in anthocyanins are blackberry (Rubus fruticosus) and grapes (Vitis vinifera).

ANTHRAQUINONES

Compounds which have a strong laxative effect. Found in plants such as senna (Cassia senna) and Chinese rhubarb (Rheum palmatum). Used as dyes.

AROMATIC PLANT

A plant containing substantially high levels of volatile oil.

BITTERS

Plant products that have a bitter taste, which stimulate saliva secretions and digestive juices, causing an increase in appetite. Found in plants such as wormwood (Artemisia absinthium) and chiretta (Swertia chirata). Some are also poisonous as in the example of the tropical plant nux vomica, which contains strychnine.

CARDIAC GLYCOSIDES

Steroid glycosides which have stimulative effects on the heart, for example digitoxin, digoxin and gitoxin from the foxglove (Digitalis sp.). They help to support the rate and strength of the hearts contraction when it is failing, and are strongly diuretic (increase urine output).

CYANOGENIC GLYCOSIDES

Poisonous glycosides produced by certain plants, such as white clover (Trifolium repens), cherry laurel (Prunus laurocerasus), cassava (Manihot esculenta) and elder (Sambucus nigra). Used in plant defense against attack. Releases hydrogen cyanide after tissue disruption. Has sedative and relaxant effects on heart muscles in small doses.

DOCTRINE OF SIGNATURES

The belief that a plant's appearance was directly related to its medicinal use.

FLAVONOIDS

A group of anti-inflammatory compounds, which include the anthocyanins, aurones, chalcones, flavones, flavanones, and flavonols. Usually occur in combination with sugars as glycosides. Not found in algae, fungi and bacteria but in all other vascular plants and bryophytes. Some flavonoids act as pigments in flowers, as phytoalexins, and in the control of IAA activity. Very good for blood circulation.

GLUCOSINOLATES

Compounds only produced by the mustard family, which are used to reduce thyroid function, and as poultices to relieve aching joints. They increase the flow of blood to the area infected, this helps in the removal of the build-up of waste products. They are skin irritants and can cause inflammation and blistering.

GLYCOSIDES

Compound formed by the reaction of a sugar with a non-sugar molecule called the aglycone. Includes classes such as the anthoxanthin glycosides (plant pigments), the steroid glycosides, and the cyanogenic glycosides.

LATEX

Milky fluid produced in numerous plants and fungi, containing a mixture of substances such as sugars, starch grains, mineral salts and alkaloids, etc. Usually white, sometimes colourless, reddish, or yellowish. Stored in lactifers in plants and latex ducts in fungi. The latex of Brazilian rubber trees (Hevea brasiliensis) is used in commercial rubber production. Chicle, which used to be used in the production of chewing gum is from the latex of Achras zapota.

NEOTROPICS

The New World (American) tropics.

PHENOLICS

Antiseptic and anti-inflammatory compounds which contain a benzene ring directly substituted with one or more hydroxyl groups. Found in many plants and include lignin, the flavonoids, salicylic acid, thymol, coumarin and catchecol.

RESIN

Substance produced by plants such as conifers mainly when wounded. When this mixture of terpenoids, esters and polymerized acids are exposed to the air, the volatile oils evaporate to leave behind a solid or semi-solid residue to protect the wound. Commercially important resins include turpentine from pines, mastic from Pistacia lentiscus, and frankincense from Boswellia.

SAPONINS

Class of bitter-tasting glycosides with a steroid molecule as the active constituent. They are soluble in water and produce foam. Most are toxic to animals. There are two types - triterpenoid and steroidal saponins. They have high hormonal activity and are used commercially in the production of steroid hormones such as diosgen from yams (Dioscorea spp.). Are found in plants such as liquorice (Glycyrrhiza glabra) and in cowslip root (Primula veris).

SECONDARY PRODUCT

Chemical compound produced by plants, which does not have a primary function. Believed to have a function in defense and as an attractant to pollinators. Also known as a secondary metabolite.

SPICE

A highly flavoured aromatic plant derivative from tropical plants, used as a food seasoning.

STEROIDS

Lipids with four carbon rings, that have hormonal actions. Most steroids are alcohols. Others include some pseudoalkaloids and the aglycone portions of the saponins and cardiac glycosides.

TANNINS

Secondary products obtained from plants, and derived from phenolics. They cause the contraction of tissues of the body and are used to 'tan' leather (process of changing hides into leather). Other uses include dyes, stains and inks. They have a harsh astringent taste and are believed to be used by the plant as a defense against insects. The bark and gallnuts of the Oak tree (Quercus robur) and the tea plant (Camellia sinensis) and sumac (Rhus spp.) are all sources of tannins.

VOLATILE OILS

A constituent which is extracted from plants and distilled to produce essential oils. Tea tree (Melaleuca alternifolia) contains over 60 volatile compounds in its volatile oil, many of which have antiseptic properties.