ANGIOSPERMS: FLOWERING PLANTS

Abstract

The astonishing diversity of plant life is best illustrated by the Angiospermae (or Anthophyta = flowering plants). It was the fruit or seeds of these plants and the method of their propagation that made organized human societies possible. Flowering plants are the dominant feature of the natural and manmade landscapes and the main source of food, shelter, clothing, and drugs. Unlike gymnosperms that predominantly occupy cool-temperate and some tropical habitats, angiosperms have adapted to a diversity of environments through modification and/or development of specialized structures for survival in aquatic habitats or the dry deserts and from the tropical rainforest to the arctic tundra. Enclosure of the seed within the ovary (the ultimate fruit) is a unique feature of the angiosperms. The ovary is a part of a complex but delicate, short-lived flower which may be born solitary or in groups on an inflorescence. Within the flower the ovary is situated at the base of solitary or fused carpels (the gynoecium), while the pollen grains are produced in anthers (the androecium). The annual and biennial growth habits common in angiosperms are absent in ferns and gymnosperms. Even the perennial habit is modified to include monocarpic (flower and fruit once and they perish) and polycarpic (flower and fruit many times), do not apply to ferns and gymnosperms because they do not possess fruit (carpus = fruit). Herbaceous plants that constitute the majority of angiosperms are unknown in gymnosperms. Among other unique characteristics of flowering plants are the modification of leaves and stems (succulence, pitchers, trigger traps and sticky leaves with digestive enzymes; tubers, bulbs, corms, etc.) and the parasitic and saprophytic habits.