Bombacaceae Kunth

Scientific Description

Common name. Kapok-tree Family.

Habit and leaf form. Trees (often having the trunk bulging and specialised for water storage); deciduous. Leaves alternate; spiral; petiolate; non-sheathing; simple, or compound; when compound, palmate. Leaf blades dissected, or entire; often palmately lobed; pinnately veined, or palmately veined. Leaves with stipules. Stipules caducous. Leaves without a persistent basal meristem. Leaf anatomy. Complex hairs present. Complex hairs often peltate. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Often cheiropterophilous.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; in cymes. The terminal inflorescence unit cymose. Inflorescences short cymes. Flowers usually large; more or less regular; cyclic, or partially acyclic. Sometimes the androecium acyclic. Perianth with distinct calyx and corolla, or sepaline (the corolla sometimes absent); 10, or 5 (rarely); 2 -whorled; isomerous. Calyx 5; 1 -whorled; polysepalous, or gamosepalous (basally); valvate (with glandular hairs at the base). Epicalyx present (often), or absent. Corolla when present (i.e. usually), 5; 1 -whorled; contorted. Androecium 5–100 (i.e. to ‘many’). Androecial members commonly interpretable as branched. Androecial sequence determinable, or not determinable. Androecial members when numerous, maturing centrifugally; free of the perianth; coherent (generally), or free of one another; when cohering, 1 - adelphous, or 5 - adelphous (in 5–15 separate bundles, or the bundles basally connate into a tube). Androecium exclusively of fertile stamens, or including staminodes. Stamens 5–1100 (usually ‘many’); isomerous with the perianth to polystemonous. Anthers dehiscing via longitudinal slits; introrse; unilocular. Gynoecium 2–5(–8) carpelled. The pistil 2–5(–8) celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 2–5(–8) locular. Styles 1. Stigmas dry type; papillate; Group II type. Placentation axile. Ovules 2–6 per locule (?— ‘2 or more’); ascending; arillate (often), or non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy (usually), or fleshy (rarely); usually dehiscent, or indehiscent (rarely); nearly always a capsule. Capsules loculicidal (usually), or valvular (occasionally). Seeds scantily endospermic, or non-endospermic. Endosperm when present, oily. Cotyledons 2. Embryo chlorophyllous (3/3); often curved. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Photosynthetic pathway: C₃.

Geography, cytology, number of species. World distribution: widespread, especially America. X = mainly 28, 36 or 40. 180 species.

Economic uses, etc. ‘Durian’ is the fruit of Durio zebethinus; Ceiba fruit supplies kapok; very light wood (balsa, corkwood) from Ochroma.