Polyalthia Blume

Scientific Description

Family Annonaceae.

Badly in need of revision (Kessler 1993:114).

Habit and leaf form. Trees, or shrubs. ‘Normal’ plants. Leaves well developed. Plants with roots; unarmed; autotrophic. To 15 m high (in Australia). Self supporting. Mesophytic. Not heterophyllous. Leaves medium-sized; alternate; distichous (in Australia); with blades; leathery (‘subcoriaceous’); petiolate (in Australia); simple; not peltate; epulvinate. Leaf blades neither inverted nor twisted through 90 degrees; entire; flat; ovate, or ovate and elliptic (in Australia). Mature leaf blades adaxially glabrous; abaxially glabrous. Leaves without stipules. Leaf blade margins entire; flat. Leaf anatomy. Hairs absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Plants homostylous.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’ (rarely); axillary. Inflorescence few-flowered. Inflorescences axillary, or leaf-opposed; solitary or clustered on woody outgrowths of older branches. Flowers pedicellate; bracteate; medium-sized; regular; not resupinate; 3(–4) merous; cyclic; pentacyclic. Perianth with distinct calyx and corolla; 9(–12); 3 -whorled; isomerous. Calyx present; 3 (in Australia); 1 -whorled; polysepalous, or gamosepalous; minutely hairy (in Australia); valvate; regular. Sepals broadly ovate. Calyx lobes broadly ovate. Corolla present; 6 (in Australia); 2 -whorled; polypetalous; valvate; glabrous abaxially, or hairy abaxially (minutely); glabrous adaxially, or hairy adaxially (minutely); green to yellow (in Australia). Petals narrowly oblong. Androecium present. Fertile stamens present. Androecial members indefinite in number. Androecium 100 (‘numerous’). Androecial members free of one another. Androecium exclusively of fertile stamens. Stamens 100 (‘numerous’); polystemonous; with sessile anthers, or filantherous (subsessile). Anthers separate from one another; dehiscing via longitudinal slits; tetrasporangiate. Fertile gynoecium present (in Australia). Gynoecium 100 carpelled (‘numerous’ in Australia). Carpels increased in number relative to the perianth. Gynoecium apocarpous; eu-apocarpous; partly inferior. Carpel stylate; apically stigmatic; 1–5 ovuled.

Fruit and seed features. Fruit 12–17 mm long (in Australia); not hairy (in Australia). The fruiting carpel indehiscent. Dispersal unit the seed. Fruit 2–5 seeded.

Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia and Northern Territory. Northern Botanical Province. A genus of ca 100 species; 1 species in Western Australia; P. australis (Benth.) Jessup; 0 endemic to Western Australia.