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The families of flowering plants

L. Watson and M.J. Dallwitz

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 crystals. The crystals raphides. Foliar vessels absent. Minor leaf veins without phloem transfer cells (Orchidantha).

Axial (stem, wood) anatomy. Secondary thickening absent. The axial 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 beetles, or via diptera.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in cymes (the flowers held upside down, lasting only one day). The ultimate inflorescence units cymose. Inflorescences terminal (terminating each shoot generation of the rhizome); few-flowered cymes. Flowers bracteate; malodorous; very irregular; zygomorphic (superficially orchid-like); 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; conspicuously hairy. Embryo well differentiated. Cotyledons 1. Testa operculate (opposite the radicle); encrusted with phytomelan; black (?).

Physiology, phytochemistry. 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 III core angiosperms; Superorder Lilianae; commelinid Monocot. APG IV Order Zingiberales.

Species about 18. Genera 1; only genus, Orchidantha (Lowia).

Illustrations. • Orchidantha maxillarioides (as Lowia): Bot. Mag. 120 (1894).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 5th March 2018.’.