|Kelly W. Allred|
Plants annual or perennial; sometimes
rhizomatous or stoloniferous. Culms 10-60 cm, usually compressed; internodes
solid. Leaves cauline; sheaths shorter than the internodes, compressed;
ligules membranous and ciliate or of hairs; blades flat or folded.
Inflorescences spikelike panicles; branches very short, with fewer
than 10 spikelets, appressed to and partially embedded in the flattened, corky
rachises; disarticulation below the glumes, often with a segment of the
branch. Spikelets lanceolate to ovate, unawned, lower glumes oriented away
from the branch axes. Glumes membranous; lower glumes scalelike,
usually without veins; upper glumes 5-7-veined; lower florets staminate
or sterile, lemmas 3-9-veined; upper florets bisexual; upper lemmas
longer than the glumes, papery to subcoriaceous, 3-5-veined; upper paleas
generally indurate, 2-veined; anthers 3. Caryopses lanceolate to
ovate, often failing to develop. x = 9. Name from the Greek stenos,
narrow, and taphros, trench, referring to the cavities in the rachis.
Stenotaphrum is a genus of seven species that usually grow on the seashore or near the coast, primarily along the Indian Ocean rim. Three species are endemic to Madagascar, and one species is thought to be native to the Flora region.
1. Stenotaphrum secundatum (Walter) Kuntze
St. Augustine Grass
Plants stoloniferous. Culms 10-30 cm, decumbent, rooting at the lower nodes, branched above the base, with prominent prophylls. Sheaths sparsely pilose, constricted at the summit; ligules about 0.5 mm, membranous, ciliate; blades 3-15(18) cm long, 4-10 mm wide, thick, flat, glabrous, apices blunt. Panicles 4.5-10 cm long, less than 1 cm wide; rachises flattened, winged; branches 12-20, with 1-5 spikelets. Spikelets 3.5-5 mm, partially embedded in 1 side of the branch axes; lower glumes about 1 mm, rounded, irregularly toothed; upper glumes and lower lemmas about equal, 3-4 mm; upper lemmas papery, 5-veined, margins weakly clasping the paleas; anthers 2-2.5 mm, tan or purple. Caryopses about 2 mm, oblong to obovate. 2n = 18.
Stenotaphrum secundatum grows on sandy beaches, at the edges of swamps and lagoons, and along inland streams and lakes. It may be native to the southeastern United States, being known from the Carolinas prior to 1800, but it has become naturalized in most tropical and subtropical regions of the world.
Stenotaphrum secundatum is planted for turf in the southern United States and is now established from California to North Carolina and Florida. Numerous cultivars have been developed. Specimens with variegated foliage, often called S. secundatum var. variegatum Hitchc., are sometimes used as an ornamental in hanging baskets and greenhouses.