Morphology of Flowering Plants — Class 11 Biology

This chapter describes the external form of angiosperms and the standard terms used to describe them. The root system may be a tap root (typical of dicots), a fibrous root system (typical of monocots) or adventitious roots, and the root shows regions of meristematic activity, elongation and maturation, with root hairs absorbing water and minerals. The stem bears nodes and internodes and conducts materials while supporting branches, leaves, flowers and fruits. Leaves arise at nodes and may be simple or compound, with venation reticulate (dicots) or parallel (monocots), and arranged by various patterns of phyllotaxy. The chapter then turns to reproductive morphology: the inflorescence (racemose or cymose) and the flower, the reproductive unit with four whorls, calyx, corolla, androecium and gynoecium, described by symmetry, position of the ovary (hypogynous, perigynous, epigynous), aestivation and placentation. After fertilisation the ovary becomes the fruit and ovules become seeds, whose dicot and monocot structures differ. Finally the chapter shows how a flowering plant is described semi-technically using floral diagrams and floral formulae, illustrated by the family Solanaceae.