Alectryon Gaertn.

Scientific Description

Family Sapindaceae.

Includes Heterodendrum following Reynolds (1987).

Habit and leaf form. Trees, or shrubs; laticiferous, or non-laticiferous and without coloured juice. Stem internodes solid. To 5 m high. Mesophytic. Heterophyllous, or not heterophyllous. Leaves fasciculate, or not fasciculate; alternate; spiral; petiolate; non-sheathing; gland-dotted, or not gland-dotted; simple, or compound; pulvinate; pinnate; paripinnate. Leaflets 2–10. Lateral leaflets opposite. Leaflets elliptic, or obovate; unequal, truncate, obtuse. Leaf blades dissected (lobed), or entire; midvein prominent; cross-venulate. Leaves without stipules. Leaf blade margins entire, or serrate (to serrulate), or dentate (to denticulate). Leaf anatomy. Hairs present, or absent; glandular hairs absent; complex hairs absent. Branched hairs absent. Extra-floral nectaries absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring, or anomalous.

Reproductive type, pollination. Fertile flowers hermaphrodite, or functionally male and functionally female. Unisexual flowers present, or absent. Plants hermaphrodite, or monoecious, or polygamodioecious. Female flowers with staminodes. Male flowers with pistillodes.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; in cymes, or in racemes (raceme-like), or in fascicles, or in panicles (panicle-like). Inflorescences simple, or compound. The terminal inflorescence unit cymose. Inflorescences terminal, or axillary. Flowers pedicellate, or subsessile; bracteate (small to minute, ovate); ebracteolate; small; regular; 4 merous, or 5 merous; cyclic. Free hypanthium absent. Hypogynous disk present; extrastaminal; annular. Perianth with distinct calyx and corolla, or sepaline; 5, or 8–10; 1 -whorled, or 2 -whorled; isomerous (usually), or anisomerous. Calyx present; 4–6; 1 -whorled; gamosepalous; entire, or lobed; shallowly blunt-lobed (or truncate), or toothed (5–10 toothed); imbricate, or valvate; unequal but not bilabiate, or regular; green, or white, or cream, or yellow, or red, or pink; with the median member posterior (when sepals 5). Calyx lobes ovate. Corolla present, or absent; 4–5; 1 -whorled; appendiculate (with a small reflexed scale); polypetalous; imbricate; unequal but not bilabiate; cream, or red, or pink. Petals ovate (broadly); clawed (shortly). Androecium present. Fertile stamens present, or absent (female flowers). Androecial members definite in number. Androecium 5–12. Androecial members free of the perianth; free of one another; 2 -whorled, or 1 -whorled. Androecium of male-fertile flowers exclusively of fertile stamens. Stamens 5–12; becoming exserted; all more or less similar in shape; isomerous with the perianth to diplostemonous; round the ovary within the disc; filantherous. Anthers dorsifixed, or basifixed; more or less versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged, or unappendaged. The anther appendages apical (by connective extension). Fertile gynoecium present, or absent (male flowers). Gynoecium 2–4 carpelled. The pistil 2–4 celled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 2–4 locular; sessile. Gynoecium stylate. Styles 1; simple; attenuate from the ovary; apical. Stigmas 1. Placentation axile to basal. Ovules 1 per locule; funicled; ascending (the micropyle down); arillate; hemianatropous, or anatropous, or campylotropous, or amphitropous.

Fruit and seed features. Fruit non-fleshy (crustaceous); dehiscent (pericarps splitting irregularly), or indehiscent; a capsule, or capsular-indehiscent. Capsules splitting irregularly. Dispersal unit the seed. Dispersal presumably by birds and animals attracted by the coloured aril. Fruit 2–4 seeded. Seeds 1 per locule. Seeds non-endospermic; arillate. Cotyledons 2. Embryo curved, or bent, or coiled. Testa black (and partially to nearly completely covered by the bright red aril).

Geography, cytology, number of species. World distribution: Hawaii, south east Asia, Australia, New Zealand. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, New South Wales, and Victoria. Northern Botanical Province, Eremaean Botanical Province, and South-West Botanical Province. A genus of 35 species; 3 species in Western Australia; 1 endemic to Western Australia.

Etymology. From the Greek for "a cock", possibly because of a comb-like crest on the fruit of some species.