Plant species

Starch is a polysaccharide found in many plant species. Com and potatoes are two common sources of industrial starch. The composition of starch varies somewhat in terms of the amount of branching of the polymer chains (11). Its principal use as a flocculant is in the Bayer process for extracting aluminum from bauxite ore. The digestion of bauxite in sodium hydroxide solution produces a suspension of finely divided iron minerals and siUcates, called red mud, in a highly alkaline Hquor. Starch is used to settle the red mud so that relatively pure alumina can be produced from the clarified Hquor. It has been largely replaced by acryHc acid and acrylamide-based (11,12) polymers, although a number of plants stiH add some starch in addition to synthetic polymers to reduce the level of residual suspended soHds in the Hquor. Starch [9005-25-8] can be modified with various reagents to produce semisynthetic polymers. The principal one of these is cationic starch, which is used as a retention aid in paper production as a component of a dual system (13,14) or a microparticle system (15). 

Fluoroacetic acid [144-49-OJ, FCH2COOH, is noted for its high, toxicity to animals, including humans. It is sold in the form of its sodium salt as a rodenticide and general mammalian pest control agent. The acid has mp, 33°C bp, 165°C heat of combustion, —715.8 kJ/mol( —171.08 kcal/mol) (1) enthalpy of vaporization, 83.89 kJ /mol (20.05 kcal/mol) (2). Some thermodynamic and transport properties of its aqueous solutions have been pubHshed (3), as has the molecular stmcture of the acid as deterrnined by microwave spectroscopy (4). Although first prepared in 1896 (5), its unusual toxicity was not pubhshed until 50 years later (6). The acid is the toxic constituent of a South African plant Dichapetalum i mosum better known as gifirlaar (7). At least 24 other poisonous plant species are known to contain it (8). 

Overall research on the development of herbaceous energy crops shows that a broad range of plant species may ultimately be prime energy crops. 

Plants and microorganisms produce unique and diverse chemical stmctures, some of which act as immunomodulators (18—28). Of specimens used in traditional medicine, approximately 450 plant species have shown antiviral activity out of 4000 plants screened (19). Several tannins (20) exhibit strong inhibition of tumor promotion experimentally. Pretreatment of mice with small amounts of tannins for several days strongly rejected transplanted tumors. This activity has been claimed to be effected through enhancement of host-mediated antitumor activity. 

L v ndin. Lavandin, Lavandula hjbrida as a plant species is of recent origin, unknown until the late 1920s. It is a hybrid of two common lavenders, l vandula officinalis and l vandula latifolia. Lavandin is cultivated mainly ia southern France and has become one of the most produced and used natural perfumery materials. The flowering tops of the shmb are used to produce a concrete, an absolute, and a steam-distilled oil the last is by far the most used. Low cost and refreshing odor quaUty allow lavandin to be employed ia a wide variety of perfume appHcations and at high concentrations. Chemically it is comprised of 30—32% linalool (3) and linalyl acetate (1), along with numerous other substances, mosdy terpenic. 

Although the antibacterial and antifungal activities of bialaphos and phosphinothricin were not found to be usehil, the two agents were later used as biodegradeable, relatively nonselective, postemergent herbicides. Glutamine synthetase inhibition is toxic to plants because the enzyme is key to ammonia assimilation. There is some selectivity for individual plant species as shown by the LD for bialaphos ranging from 0.125 to 8.5 kg/ha (301—303). 

Nitrate is one of the facts of life. It is essential for the growth of many plant species, including most of those we eat, but it becomes a problem if it gets into water in which it is not wanted. It is perceived mainly as a chemical fertilizer used by farmers, but much of the nitrate found in soil is produced by the microbes that break down plant residues and other nitrogen-containing residues in the soil. There is no difference between nitrate from fertilizer and that produced by microbes, but, whatever its origin, this rather commonplace chemical entity has now become a major environmental problem and is also treated as a health hazard. 

The extent and severity of the damage attributable to acid depositions are difficult to estimate, since impacts vary according to soil type, plant species, atmospheric conditions, insect populations, and other factors that are not well understood. Nitrates in precipitation may actually increase forest growth in areas with nitrogen-deficient soils. 

Where regional development is to be undertaken it is reasonable to adopt a positive ecological approach. This can begin with the formulation of a conservation policy with specific goals. These may include the conservation of individual animal/plant species or habitat types which are threatened by development. A program of conservation projects (e.g. the setting up of national parks, country parks or natural reserves) will meet the goals. This positive approach to the ecosystem will not only benefit wildlife but will also create the opportunities for tourism and leisure, which are vital adjuncts to most development projects. 

Extracts from 152 plant species, representing 46 different families, were screened for effects on tobacco mosaic virus (TMV) replication in cucumber cotyledons. Twenty species have shown enough activity to warrant further study. Several members of the Caprifoliaceae family increased virus replication. An extract of Lonicera involucrata enlarged the virus lesions in local lesion hosts and produced a thirty fold increase in virus titer, but had no effect on virus replication in systemic hosts. The active material appears to affect the virus defense mechanism of local lesion hosts. An extract of common geranium is an active virus inhibitor. It inactivates TMV and TMV-RNA (ribonucleic acid) in vitro by forming non-infectious complexes. In vivo, it also inhibited starch lesion formation in cucumber cotyledons incited by TMV infection. 

Coumarin, the lactone of o-hydroxycinnamic acid, and some of its derivatives have been isolated from many plant species 31). Thimann and Bonner 141) attributed the growth-inhibiting effects of coumarin to its action on enzyme sulfhydryl groups. Inhibitory effects of coumarin on Avena coleoptiles and pea stem sections could be overcome by 2,3-dimercaptopropanol (BAL). Coumarin has also been reported to disrupt mitosis 29,30). 

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