Stemodia L.
Syst.Nat. Ed.10:1118 (1759)

Name Status: Current
Browse to the list of specimens for Stemodia L.

Scientific Description
H.R. Coleman, Thursday 8 September 2016

Common name. Stemodias. Family Scrophulariaceae.

Includes Morgania.

Habit and leaf form. Shrubs, or herbs. Annual, or perennial. Leaves basal and cauline. Plants with neither basal nor terminal concentrations of leaves. Stem internodes solid. To 1 m high. Helophytic, or mesophytic, or xerophytic. Leaves small to medium-sized; opposite, or whorled; 3 per whorl, or 4 per whorl; ‘herbaceous’, or leathery, or membranous; petiolate, or sessile; not connate; aromatic, or without marked odour; simple; epulvinate. Leaf blades entire; linear, or ovate, or obovate, or elliptic; pinnately veined; auriculate at the base, or cuneate at the base, or rounded at the base. Mature leaf blades adaxially glabrous, or pubescent, or villous; abaxially glabrous, or pubescent, or villous. Leaves without stipules. Leaf blade margins entire, or serrate, or dentate. Leaves without a persistent basal meristem. Leaf anatomy. Hydathodes present (occasionally), or absent. Hairs present, or absent; glandular hairs present, or absent. Stem anatomy. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in racemes, or in spikes, or in panicles. Inflorescences simple, or compound. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal, or axillary; racemose, slender, more or less dense, flowers single or clustered in the bract axils. Flowers pedicellate to sessile; bracteate; bracteolate; small to medium-sized; very irregular; zygomorphic; 5 merous; tetracyclic. Free hypanthium absent. Hypogynous disk present. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; polysepalous (sepals more or less equal or unequal); erect; imbricate, or valvate; persistent; with the median member posterior. Sepals ovate, or triangular. Corolla present; 5; 1 -whorled; gamopetalous; lobed; imbricate, or valvate; bilabiate; glabrous abaxially; glabrous adaxially; with contrasting markings; green, or white, or yellow, or purple, or blue. Androecium 4. Androecial members adnate (to the corolla); markedly unequal; coherent (paired anthers connate); 1 -whorled. Stamens 4; didynamous; reduced in number relative to the adjacent perianth; oppositisepalous. Anthers cohering (in pairs); dehiscing via longitudinal slits; introrse; bilocular (cells separate, equal, stipitate); tetrasporangiate. Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium non-petaloid; syncarpous; synstylovarious to eu-syncarpous; superior. Ovary plurilocular; 2 locular. Gynoecium median; stylate. Styles 1; simple; attenuate from the ovary, or from a depression at the top of the ovary; apical; persistent. Stigmas 1; 2 - lobed. Placentation axile, or apical. Ovules 50 per locule (to ‘many’); pendulous to ascending; non-arillate; anatropous, or campylotropous, or hemianatropous.

Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules septicidal, or septicidal and loculicidal (then secondarily loculicidal, the remnants of the septum remaining attached to the 2 or 4 valves, the central column free). Fruit 50 seeded (to ‘many’). Seeds endospermic. Endosperm oily. Seeds minute. Cotyledons 2. Embryo straight to curved.

Special features. Corolla tube exceeding the calyx, or not exceeding the calyx; straight. The upper lip of the corolla incorporating 2 members, the lower 3; (posterior, adaxial) lip of the corolla bilobed (recurved). Lower (abaxial) lip of the corolla 3 lobed.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, New South Wales, and Victoria. Northern Botanical Province and Eremaean Botanical Province.

Etymology. From the Greek for "thread, stamen" and "double"; appears to refer to the separate anther cells.

Taxonomic Literature

  • Wheeler, J. R.; Rye, B. L.; Koch, B. L.; Wilson, A. J. G.; Western Australian Herbarium (1992). Flora of the Kimberley region. Western Australian Herbarium. Como, W.A.
  • Barker, W. R. (1990). New taxa, names and combinations in Lindernia, Peplidium, Stemodia and Striga (Scrophulariaceae) mainly of the Kimberley Region, Western Australia.
  • Grieve, Brian J.; Blackall, William E. (1982). How to know Western Australian wildflowers : a key to the flora of the extratropical regions of Western Australia. Part IV. University of W.A. Press. Perth.