Hydroponics

Categories Agriculture disciplines economic botany and plant uses gardening water-related life Literally water culture, hydroponics originally referred to the growth of plants in a liquid medium. It now applies to all systems used to grow plants in nutrient solutions with or without the addition of synthetic soil for mechanical support. Hydroponics has become an important method of crop production with the increase in the number of commercial greenhouse operations. Greenhouses are utilized in...

Public Policy and Public Awareness

Since the early twentieth century, forest fires have engendered public policy in the United States. In the aftermath of major fires in 1903 and 1908 in Maine and New York, state fire organizations and private timber protective associations were formed to provide fire protection. These, in turn, contributed to the Weeks Act of 1911, which permitted co operative fire protection between federal and state governments. People who make their homes in woodland settings in or near forests face the...

Medicinal Alkaloids

Many potentially toxic plant-derived alkaloids have medicinal properties, as long as they are administered in carefully regulated doses. Alkaloids with important medicinal uses include morphine and codeine from the opium poppy and cocaine from the coca plant. These alkaloids act on the nervous system and are used as painkillers. Atropine, from the deadly nightshade plant, also acts on the nervous system and is used in anesthesia and ophthalmology. Vincristine and vinblastine from the periwinkle...

Habitat Loss

By far the most significant threat to plant species is habitat loss or destruction. Habitat loss can occur because of resource harvesting for food, medicine, and other products, deforestation, and the conversion of wilderness for agricultural, industrial, or urban uses. Wood consumption and tree clearing for agriculture and development threaten the world's forests, especially the tropical forests, which may disappear by the mid-twenty-first century if sufficient preventive action is not taken....

Nitrogen Fertilizer from Legumes

The importance of legumes as a green fertilizer has been recognized for centuries. As early as the third century b.c.e., the Greek philosopher and scientist Theophrastus recommended that beans should be planted to enrich farm soils. Then, as now, a common agricultural practice was to rotate cereal crops, such as corn or wheat, with legumi nous crops, such as clover or alfalfa (Medicago sativa). The legumes used as green fertilizer not only contribute nitrogen to the soil but also can be...

Fighting Asthma Gastrointestinal Disorders Parasites

The major anti-asthma drugs come from ephed-rine, extracted from the ma huang plant (Ephedra sinaica), and its structural derivatives. Plant-derived drugs that affect the gastrointestinal tract include castor oil, senna, and aloes as laxatives, opiate alkaloids as antidiarrheals, and ipecac from Cephaelis acuminata as an emetic. The most useful plant-derived antiparasitic agent is quinine, derived from the bark of the chincona plant (Chincona succirubra). Quinine has been used to control...

Habitats

Marine plants live in diverse habitats near shores or in salt marshes and open seas worldwide. Giant kelp, a seaweed found in the South Pacific, grows in groups in warm coastal waters. In contrast, sea ice algae live on floating ice sheets. Migrating marine plants drift in a variety of water conditions. On reefs, marine plants have several roles. Primarily, marine plants, including macroalgae and sea grasses, provide nourishment and shelter for animals. Marine plants assist corals in...

Isoflavonoids as Phytoestrogens

Isoflavonoids are a type of secondary metabolite and are found almost exclusively in the legume pea family of plants. They are known to function in plant defense. They have been shown to deter herbivores and also to facilitate a plant's defense response to pathogen attack. Interestingly, some isoflavonoids have chemical structures that, in overall size, shape, and polarity, resemble estrogens. The resemblance includes the flatness, or planarity, of the molecules and the positions and...

Fruit Types

Fruits can be classified, based on the nature of the pericarp, into two groups fleshy and dry. Fleshy fruits, in turn, are classified into several types, including drupes, berries, pomes, hesperidia, and pepos. Dry fruits are also subdivided into several categories, including follicles, legumes, capsules, achenes, nuts, samaras, schizocarps, and caryopses. The three most familiar types of fleshy fruits are drupes, berries, and pomes. Adrupe is a fleshy fruit that contains a single seed...

Simple and Compound Leaves

Simple Leaf And Compound Leaf

To discriminate between simple and compound leaves, one may locate the axillary bud at the base of a leaf petiole in the node region of the stem. This area signifies the basal end of the entire leaf in both simple and compound leaves. A simple leaf has only one blade, or lamina, associated with it. There are no leaflets. In singly compound leaves, the leaf is sudivided into leaflets, which attach to a central rachis axis . The rachis is continuous with the petiole, which attaches to the node...

List Of Illustrations Charts And Tables

Acid Precipitation pH Scale bar Africa, Desertification of African Countries with More than 15 Percent Arable Land, Leading Agricultural Crops of table . . . I-15 African Rain Forests Africa's Agricultural Products Air Pollutant Emissions by Pollutant and Source, 1998 table I-45 Algae, Classification of Algae, Types of Angiosperm, Life Cycle of an Angiosperms and Continental Drift Antibiotic Resistance, The Growth of Ants and Acacias Asian Countries with More than 15 Percent Arable Land,...

Economic Importance

The chemical substances produced by endo-phytic fungi are of considerable commercial interest to the pharmaceutical and food-processing industries and as potential biocontrol agents for plant diseases and pests. Endophytic fungi may eventually help farmers grow crops with minimal use of water, fertilizers, and pesticides. See also Animal-plant interactions Ascomycetes Biopesticides Community-ecosystem interactions Drought Fungi Mycorrhizae Resistance to plant diseases.

Alphabetical List Of Contents

Acid precipitation 1 Active transport 4 Adaptive radiation 10 African agriculture 12 Agricultural crops experimental 20 Agricultural revolution 23 Agriculture history and overview 24 Agriculture marine 29 Agriculture modern problems 31 Agriculture traditional 34 Agriculture world food supplies 37 Alternative grains 52 Anaerobes and heterotrophs 54 Anaerobic photosynthesis 56 Angiosperm cells and tissues 58 Angiosperm evolution 61 Angiosperm life cycle 65 Angiosperm plant formation 69...

Garden Plants Shrubs

Categories Angiosperms economic botany and plant uses gardening Shrubs are perennial, woody plants that have multiple ecological uses and are economically important for a variety of landscape purposes. Like trees, the shrubs consist of both primary and secondary cambium cells that ultimately form wood or bark , but unlike trees, shrubs typically have multiple stems and are somewhat shorter in height. Native and nonnative shrubs have many uses, both in private gardens and as elements in...