Habit and leaf form. Achlorophyllous, pallid or purplish herbs (lacking stomata, raphides and silica bodies). Leaves much reduced. Plants with roots; saprophytic. With neither basal nor terminal aggregations of leaves. Mesophytic. Leaves minute, or small; alternate; membranous; not imbricate; sessile; non-sheathing; simple. Lamina entire; one-veined; without cross-venules.
Leaf anatomy. Stomata absent.
The mesophyll without calcium oxalate crystals. Vessels absent.
Stem anatomy. Secondary thickening absent. Xylem without vessels.
Root anatomy. Root xylem without vessels (Andruris).
Reproductive type, pollination. Monoecious, or dioecious, or polygamomonoecious (?), or hermaphrodite (rarely - in some Sciaphila species).
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in `inflorescences'; in racemes (usually), or in cymes. The terminal inflorescence unit racemose (usually), or cymose. Inflorescences terminal; sympodial in Triuris, otherwise racemes. Flowers bracteate; small; regular; cyclic; tetracyclic. Floral receptacle developing an androphore (an androphore), or developing a gynophore; not markedly hollowed. Perigone tube present (short, the lobes often reflexed).
Perianth of `tepals'; (3-)6(-10); joined; 1 whorled; petaloid.
Androecium (2-)3(-6). Androecial members free of the perianth; all equal; free of one another, or coherent; 1 - whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes non-petaloid. Stamens (2-)3(-6); filantherous, or with sessile anthers. Anthers non-versatile; dehiscing via longitudinal slits, or dehiscing transversely (commonly); extrorse; bilocular to four locular; bisporangiate to tetrasporangiate; appendaged (by extension of the connective), or unappendaged. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis successive. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with one middle layer. Tapetum probably glandular. Pollen shed as single grains. Pollen grains nonaperturate; 3-celled.
Gynoecium 6-50. Carpels isomerous with the perianth, or reduced in number relative to the perianth, or increased in number relative to the perianth. Gynoecium apocarpous; eu-apocarpous; superior. Carpel stylate; with a lateral style, or with a gynobasic style; 1 ovuled. Placentation basal. Ovules funicled; ascending; non-arillate; anatropous; bitegmic; tenuinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids pear-shaped. Endosperm formation nuclear.
Fruit non-fleshy; multiple. The fruiting carpel dehiscent (usually), or indehiscent (Soridium); a follicle, or an achene. Seeds copiously endospermic. Endosperm oily. Embryo rudimentary at the time of seed release.
Geography, cytology. Tropical. Pantropical and subtropical. X = 11, 12, 14.
Taxonomy. Subclass Monocotyledonae. Superorder Triuridiflorae; Triuridales. Species 80. Genera 7; Andruris, Hexuris, Hyalisma, Sciaphila, Seychellaris, Soridium, Triuris.
Illustrations. triur144.gif
