Pachygone Miers

Scientific Description

Family Menispermaceae.

Habit and leaf form. Lianas; non-laticiferous and without coloured juice (in Australia). ‘Normal’ plants. Leaves well developed. Plants with roots; autotrophic. To 15 m high (in Australia). Climbing. Mesophytic. Not heterophyllous. Leaves medium-sized; alternate; spiral; with blades; membranous (‘papyraceous’); petiolate; simple; not peltate; epulvinate. Leaf blades neither inverted nor twisted through 90 degrees; entire; flat; ovate. Mature leaf blades adaxially sparsely pubescent; abaxially sparsely pubescent. Leaves without stipules. Leaf blade margins entire; flat. Leaf anatomy. Hairs present, or absent.

Reproductive type, pollination. Fertile flowers functionally male and functionally female. Unisexual flowers present. Plants dioecious. Plants homostylous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in racemes (‘pseudo-racemose’). Inflorescences simple. The terminal inflorescence unit racemose. Inflorescences axillary. Flowers pedicellate; bracteate (subulate); minute (in Australia); regular; not resupinate; 3 merous; cyclic. Perianth with distinct calyx and corolla; 12(–18); 4–6 -whorled; isomerous. Calyx present; 6–12; 2–4 -whorled; polysepalous; yellow. Sepals elliptic to orbicular. Corolla present; 6; 2 -whorled; polypetalous; valvate; hairy abaxially (in Australia); hairy adaxially (in Australia). Petals oblong. Androecium present, or absent. Fertile stamens present, or absent. Androecial members definite in number. Androecium 6. Androecial members coherent (very shortly adnate at the base to the corolla). Androecium exclusively of fertile stamens (but 6 staminodes only present in female flowers). Stamens 6; diplostemonous; filantherous. Anthers separate from one another; dehiscing via longitudinal slits; tetrasporangiate. Fertile gynoecium present, or absent. Gynoecium 3 carpelled. Carpels isomerous with the perianth. Gynoecium apocarpous; eu-apocarpous. Carpel stylate; apically stigmatic. Style bent (‘reflexed’). Carpel 2 ovuled (‘but only 1 developing’).

Fruit and seed features. Fruit ca 6 mm long; stipitate; an aggregate. The fruiting carpel indehiscent; drupaceous. Dispersal unit the seed. Fruit 1 seeded.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, Northern Territory, and Queensland. Northern Botanical Province. A genus of ca 12 species; 1 species in Western Australia; P. ovata (Poiret) J.D. Hook. & Thomson; 0 endemic to Western Australia.