Syst. Nat. ed. 10, 2: 1091, 1118, 1374. 1759. name conserved
Herbs [suffruticose herbs], annual or perennial. Stems erect, ascending, decumbent, or prostrate, hairy [glabrous]. Leaves cauline, opposite or whorled; petiole absent [present]; blade not fleshy, not leathery, margins serrate or denticulate. Inflorescences terminal or axillary, spikes, racemes, or flowers solitary; bracts present or absent. Pedicels present or absent; bracteoles smaller than calyx lobes, not surrounding calyx of flower they subtend. Flowers bisexual; sepals 5, basally connate, calyx bilaterally symmetric [radially symmetric], tubular, lobes narrowly lanceolate to narrowly triangular, outer lobes ± as wide as inner; corolla blue-purple, lavender, or white, bilaterally symmetric, bilabiate, tubular, tube base not spurred or gibbous, lobes 5, abaxial 3, adaxial 2; stamens 4, proximally adnate to corolla, didynamous, filaments glabrous [hairy]; staminode 0 or 1, short-cylindric [filiform]; ovary 2-locular, placentation axile; stigma capitate, 2-lobed. Fruits capsules, dehiscence loculicidal, 4-valved. Seeds 10–150, light brown [black], ovoid or ellipsoid, wings absent.
s United States, Mexico, West Indies, Central America, South America, Asia, Africa, Australia.
Species 52 (3 in the flora).
Stemodia is closely allied to Leucospora, Limnophila, and Schistophragma in Gratioleae. D. Estes and R. L. Small (2008) found Stemodia to be paraphyletic as now delimited. Of the species in the flora area, only S. schottii was sampled; it appears to be in the cluster containing S. maritima Linnaeus, the type of the genus.
Species of Stemodia can resemble other small-flowered Plantaginaceae but always can be distinguished by their distinct anther cells, their ovoid, loculicidal, four-valved capsules, and their parallel-ridged seeds. Schistophragma has pinnately lobed leaf blade margins, narrowly cylindric, septicidal fruits, and spirally ridged seeds. Leucospora is distinguished by its pinnatifid to bipinnatifid leaf blade margins, pedicels without bracteoles, and septicidal capsules. Limnophila grows in mud or shallow water and has pinnatifid blade margins of submersed leaves.
|1||Leaf blade surfaces densely white-tomentose, bases not auriculate or clasping.||Stemodia lanata|
|1||Leaf blade surfaces sparsely hairy or sparsely glandular-hairy, bases auriculate or clasping.||> 2|
|2||Inflorescences terminal, spikes, racemes, or flowers 1–4 per axil; corollas 5–8 mm.||Stemodia durantifolia|
|2||Inflorescences axillary, flowers 1 or 2 per axil; corollas 10–13 mm.||Stemodia schottii|