SEEDLING STRUCTURAL DIVERSITY AND SOME CONCEPTUAL REFLECTIONS AND TAXONOMIC IMPLICATIONS

Seedlings have importance in plant physiology, systematic botany, ecology, phylogeny investigations, population dynamics studies, forestry, seed storage, nursery work, forest conservation and regeneration, recovery of degraded areas, colonization of new environments by native or exotic species, and research into medicinal and toxic plants. Seedling is a stage of plant development, which consists of the following parts in eudicots: primary root, collet, hypocotyl, cotyledons, epicotyl and one or two opposite eophylls. The stage following the seedling is called tirodendro, which ends with the formation of the metaphyll. The seedling of monocots has a primary root, which may be ephemeral, a hypocotyl that is usually very short, a cotyledon with a basal part (hypophyll) and an upper part (hyperphyll), and the first leaf. The morphology and anatomy of the seedling and tirodendro are analyzed in this chapter. Descriptions of seedlings and tirodendros of some angiosperm families are presented in this text.