Including Tripterelleae (Tripterellaceae) Dum.Excluding Corsiaceae, Thismiaceae
Habit and leaf form. Herbs. ‘Normal’ plants, or plants of very peculiar vegetative form (some being tiny saprophytes); sometimes vegetatively almost filamentous, or fungoid. Leaves well developed, or much reduced, or absent. Plants autotrophic, or saprophytic. Annual, or perennial; with a basal aggregation of leaves, or with neither basal nor terminal aggregations of leaves. Leaves alternate; spiral (usually), or distichous; ‘herbaceous’, or membranous; sessile; sheathing. Leaf sheaths with free margins. Leaves simple. Lamina entire; usually linear to ovate; parallel-veined; without cross-venules.
General anatomy. Plants without silica bodies. Accumulated starch other than exclusively ‘pteridophyte type’.
Leaf anatomy. Stomata anomocytic.
The mesophyll containing calcium oxalate crystals (sometimes?), or without calcium oxalate crystals. The mesophyll crystals if present, not raphides. Vessels present (in some autotrophic taxa), or absent; end-walls scalariform.
Stem anatomy. Secondary thickening absent. Xylem with vessels (in some autotrophs), or without vessels. Vessel end-walls scalariform.
Root anatomy. Roots with velamen, or without velamen. Root xylem with vessels; vessel end-walls scalariform.
Reproductive type, pollination. Plants hermaphrodite, or monoecious. Floral nectaries present. Nectar secretion from the gynoecium (via septal nectaries, or from the top or sides of the ovary).
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes and in racemes. The ultimate inflorescence unit cymose. Inflorescences terminal; dichasia or monochasia. Flowers regular; 3 merous; cyclic; tetracyclic. Perigone tube present (3-winged).
Perianth of ‘tepals’; 6, or 3 (3+3, but either whorl may be reduced or obsolete); joined; 1 whorled, or 2 whorled; isomerous; petaloid; different in the two whorls (Burmannia with the inner lobes smaller or absent), or similar in the two whorls.
Androecium 3. Androecial members adnate (to the tube); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 3; isomerous with the perianth; when perianth developed, oppositiperianthial (by contrast with Iridaceae etc.). Anthers introrse to latrorse; tetrasporangiate; appendaged (often), or unappendaged. Microsporogenesis successive. Anther wall initially with one middle layer. Tapetum probably glandular. Pollen shed as single grains. Pollen grains aperturate, or nonaperturate; 1 aperturate; when aperturate, sulcate, or ulcerate; 3-celled (Apteria), or 2-celled and 3-celled (with both conditions recorded in Burmannia), or 3-celled.
Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 1 celled, or 3 celled. Gynoecium syncarpous; synstylovarious; partly inferior. Ovary 1 locular, or 3 locular. Styles 1; partially joined; apical. Stigmas 3. Placentation when unilocular parietal; when trilocular axile. Ovules in the single cavity when unilocular, 15–100 (? — ‘many’); when trilocular 10–50 per locule (? — ‘many’); anatropous; bitegmic; tenuinucellate. Embryo-sac development Polygonum-type, or Allium-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; small. Synergids pear-shaped. Endosperm formation cellular, or helobial. Embryogeny onagrad, or asterad (?).
Fruit non-fleshy; dehiscent; a capsule. Capsules splitting irregularly, or loculicidal, or valvular (rarely). Fruit 15–100 seeded (‘many’). Seeds scantily endospermic; winged. Embryo rudimentary at the time of seed release. Testa without phytomelan; thin.
Physiology, biochemistry. Saponins/sapogenins possibly present, extracts being haemolytic.
Geography, cytology. Holarctic, Paleotropical, Neotropical, Australian, and Antarctic. Temperate to tropical. Widespread, tropical, subtropical, north to Japan and eastern U.S.A., south to Tasmania and New Zealand.
Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Burmanniales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Dioscoreales.
Species 125. Genera 9; Apteria, Burmannia, Campylosiphon, Cymbocarpa, Dictyostega, Gymnosiphon, Hexapterella, Marthella, Miersiella.
• Technical details: Burmannia, Apteria.
• Technical details: Dictyostega (Lindley.