Family Lowiaceae

Lowiaceae Ridl.

Including Orchidanthaceae Dostál

Habit and leaf form. Acaulescent, glabrous herbs. Perennial; rhizomatous (the rhizome horizontal, sympodial, bearing scales, foliage leaves and inflorescences). Leaves alternate; distichous; petiolate (embracing each other by their sheaths); sheathing. Leaf sheaths tubular; with free margins. Leaves simple. Lamina entire; broadly lanceolate; pinnately veined (the laterals arching and apically convergent); rather cross-venulate. Lamina margins entire. Vernation convolute.

General anatomy. Plants with silica bodies (hat-shaped, in association with the vascular bundles).

Leaf anatomy. Epidermis without silica bodies. Stomata present; paracytic (sunken). Hairs absent.

The mesophyll containing mucilage cells (with raphides); containing calcium oxalate crystals. The mesophyll crystals raphides. Minor leaf veins without phloem transfer cells (Orchidantha). Vessels absent.

Stem anatomy. Secondary thickening absent. Xylem without vessels.

Root anatomy. Root xylem with vessels; vessel end-walls scalariform.

Reproductive type, pollination. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the gynoecium (via septal nectaries). Pollination entomophilous; presumably via diptera.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes. The ultimate inflorescence unit cymose. Inflorescences terminal (terminating each shoot generation of the rhizome); few-flowered cymes. Flowers bracteate; malodorous; very irregular; zygomorphic (superficially orchidlike); cyclic. Perigone tube present (very long and slender, stalklike).

Perianth of ‘tepals’; 6; joined; 2 whorled; isomerous; petaloid; different in the two whorls (the outer members subequal, fused into the tube below, the lobes linear-lanceolate and pointed, the inner whorl consisting of an enlarged median which forms an elliptic-spathulate or boatshaped and sometimes patterned labellum, and a pair of smaller, elliptic to filiform laterals).

Androecium 5 (the position opposite the labellum being unoccupied). Androecial members free of the perianth to adnate (to the bases of the petals); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens 5; diplostemonous; shortly filantherous. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; tetrasporangiate (elongate); appendaged. The anther appendages apical (the tip of the connective shortly subulate). Pollen shed as single grains. Pollen grains nonaperturate.

Gynoecium 3 carpelled; partly petaloid (in that the stigmatic lobes are asymmetrically broadened, flattened and marginally laciniate-fimbriate, cf. some Iridaceae). Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious; inferior. Ovary 3 locular. Gynoecium stylate. Styles 1; apical. Stigmas wet type; non-papillate. Placentation axile. Ovules 30–50 per locule (‘many’); biseriate; arillate; anatropous.

Fruit non-fleshy; dehiscent; a capsule (with papery pericarp). Seeds endospermic; globose, each enclosed by a trilobate aril. Embryo well differentiated. Cotyledons 1. Testa operculate (opposite the radicle); encrusted with phytomelan; black (?).

Physiology, biochemistry. Not cyanogenic.

Geography, cytology. Paleotropical. Sub-tropical to tropical. China and western Malaysia. X = 9.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Zingiberiflorae; Zingiberales. APG 3 core angiosperms; Superorder Lilianae; commelinid Monocot; Order Zingiberales.

Species 2. Genera 1; only genus, Orchidantha (Lowia).