Family Corsiaceae

Corsiaceae Becc.

~ Burmanniaceae, Orchidaceae

Including Achratinitaceae Barkley

Habit and leaf form. Reduced, saprophytic herbs. Leaves much reduced (to scales). Plants saprophytic. Perennial; rhizomatous, or tuberous. Mesophytic. Leaves small; alternate; spiral; membranous; sessile; sheathing; simple; epulvinate. Lamina entire; parallel-veined; without cross-venules.

General anatomy. Plants without silica bodies.

Leaf anatomy. Stomata anomocytic.

Stem anatomy. Cork cambium absent. Secondary thickening absent.

Reproductive type, pollination. Plants hermaphrodite (Corsia), or monoecious.

Inflorescence, floral, fruit and seed morphology. Flowers solitary; terminal; ebracteate; very irregular; zygomorphic. The floral irregularity involving the perianth. Flowers 3 merous; cyclic. Perigone tube present.

Perianth of ‘tepals’; 6; joined; 2 whorled (3+3); isomerous; petaloid; different in the two whorls (in that the posterior member of the outer whorl is large and coloured, and encloses the other five, which are linear-spathulate).

Androecium 6. Androecial members free of the perianth; free of one another; 2 whorled. Androecium exclusively of fertile stamens. Stamens 6; diplostemonous. Anthers dehiscing via longitudinal slits; extrorse. Microsporogenesis successive. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate, or ulcerate.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; synstylovarious; inferior. Ovary 1 locular. Gynoecium stylate. Styles 1; apical. Stigmas 3 (thick). Placentation parietal (the three placentae more or less intruded, two-lobed). Ovules in the single cavity 25–100 (i.e. ‘many’); anatropous; bitegmic; tenuinucellate. Embryo-sac development Polygonum-type. Endosperm formation helobial.

Fruit non-fleshy; dehiscent; a capsule. Capsules valvular. Fruit 25–100 seeded (‘many’). Seeds endospermic. Endosperm oily, or not oily. Seeds minute, or small; winged. Embryo rudimentary at the time of seed release. Testa without phytomelan.

Geography, cytology. Australian and Antarctic. Sub-tropical to tropical. New Guinea, Australia, Solomon Is., Chile. X = 9.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Burmanniales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Liliales.

Species 10. Genera 2; Corsia, Arachnitis.