Summary

This chapter surveyed the morphology of a flowering plant organ by organ, then applied that vocabulary to describe seven representative plant families in precise, comparable terms.

The root, developing from the radicle, shows four regions from tip to base (root cap, meristematic zone, elongation zone, maturation zone with root hairs) and is modified for storage (conical/napiform/tuberous tap roots; tuberous/fasciculated adventitious roots), mechanical support (prop roots, stilt roots, climbing roots), and special functions (pneumatophores for respiration in mangroves, nodulated roots for nitrogen fixation in legumes, haustoria in parasites).

The stem, developing from the plumule and bearing nodes and internodes, is modified underground for storage (rhizome, tuber, bulb, corm) and above ground for climbing (tendrils), defence (thorns), and photosynthesis (phylloclades) -- the presence of nodes/buds is always the decisive test for a modified stem.

The leaf is classified by venation (reticulate in most dicots, parallel in most monocots), by whether it is simple or compound (tested by the axillary bud, present only at the base of the whole leaf, never on an individual leaflet), and by phyllotaxy (alternate, opposite, or whorled).

The inflorescence is racemose (indeterminate axis, acropetal flower order, e.g. mustard) or cymose (determinate axis ending in a terminal flower, e.g. jasmine).

The flower is built of four whorls -- calyx, corolla, androecium, gynoecium -- described by symmetry (actinomorphic/zygomorphic), aestivation (valvate/twisted/imbricate/vexillary), and placentation (marginal/axile/parietal/basal/free-central), all encoded compactly in a floral formula and floral diagram.

The fruit develops from the ovary (true fruit) or from the ovary plus other floral parts (false fruit), and is fleshy (berry) or dry -- dehiscent (siliqua, legume, capsule) or indehiscent (cypsela, caryopsis) -- with its structure following directly from the parent flower's gynoecium.

The seed is dicotyledonous (two cotyledons, embryonal axis with epicotyl/plumule and hypocotyl/radicle, albuminous or exalbuminous) or monocotyledonous (one cotyledon/scutellum, large persistent endosperm, coleoptile and coleorhiza). …