Common name. Boab. Family Bombacaceae.
Tribe Adansonieae; sect. Longitubae.
Habit and leaf form. Trees (with a short enlarged trunk which is adapted for water storage, the wood soft and spongy); deciduous. Plants unarmed. To 5–30 m high. Leaves medium-sized (central leaflet largest); alternate; spiral; leathery, or membranous; petiolate (petioles bipulvinate); compound; palmate. Leaflets 3–11; elliptic, or ovate, or obovate. Leaf blades dorsiventral. Mature leaf blades adaxially glabrous, or pubescent, or woolly; abaxially glabrous, or pubescent, or woolly. Leaves with stipules. Stipules caducous. Leaf blade margins entire, or dentate. Leaf anatomy. Hairs present; complex hairs present. Complex hairs stellate.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Ornithophilous.
Inflorescence and flower features. Flowers solitary; axillary; pedicellate; bracteolate (3 bracteoles). Bracteoles deciduous. Flowers large; fragrant; regular, or very irregular (slightly). Floral receptacle developing an androphore. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous; green, or cream, or pink, or red, or brown (abaxial surface green and brown, adaxial surface pink, red or cream). Calyx present; 5; 1 -whorled; gamosepalous (splitting at anthesis into 2–5 segements); lobed; lobulate (acutely 5-lobed); spreading; hairy, or glabrous (scabrous on the outside and sericeous on the inside); valvate; exceeded by the corolla, or more or less equalling the corolla; cupuliform, or tubular; persistent, or not persistent. Epicalyx absent. Corolla present; 5; 1 -whorled; polypetalous (adnate to the base to the staminal tube); hairy abaxially; hairy adaxially; plain; white, or cream (in Australia), or yellow, or red. Petals oblong. Androecium present. Fertile stamens present. Androecial members indefinite in number. Androecium 100–1100. Androecial members coherent (connate: the filaments connate into a tube; filaments connate in the lower half, free and spreading in the upper half); 1 - adelphous (the tube attached to the petals). Androecium exclusively of fertile stamens. Stamens 100–1100. Anthers separate from one another; recurved; dehiscing via longitudinal slits (i.e. a peripheral slit); unilocular. Gynoecium usually 5 carpelled. The pistil 5 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 5 locular; sessile. Ovary summit hairy, the hairs not confined to radiating bands. Gynoecium stylate (style filiform). Styles 1; persistent, or deciduous. Stigmas 1; 5–10 - lobed. Placentation axile. Ovules 50–100 per locule (i.e. ‘many’); funicled; anatropous.
Fruit and seed features. Fruit 150–250 mm long; non-fleshy; red, or black (i.e. reddish or blackish-brown); hairy. Pericarp woody with solid septa. Fruit indehiscent; capsular-indehiscent (globular, ellipsoid or obovoid). Dispersal unit the seed. Fruit 50–100 seeded (i.e. ‘many’). Seeds compressed, or not compressed (reniform to globular); small. Cotyledons 2; folded. Embryo curved. Seedling. Germination phanerocotylar, or cryptocotylar.
Geography, cytology, number of species. World distribution: Africa, Madagascar and Australia. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia and Northern Territory. Northern Botanical Province. 2n = 88 for A. gregorii, A. grandidieri, A. suarenzensis, A. rubrostipa, A. madagascariensis, A. za and A. perrieri; 2n = 160 for A. digitata. A genus of 8 species; 1 species in Western Australia; 0 endemic to Western Australia.
Economic uses, etc. The endemic Australian species A. gregorii ( = A. gibbosa) is edible and the large branches store water which is used by the Aboriginal Australians in times of drought.
Etymology. After Michel Adanson (1727–1806), French naturalist; the first naturalist to visit and record in Senegal 1748–54. He later concentrated on classification and was a precursor of the natural system developed by Jussieu.