keys to the vascular plants of east texas - Botanical Research ...

1076 POACEAE/STENOTAPHRUM
blades 2–5 mm wide; panicles usually 6–20 cm long, ca. 1/2 as wide as long, the lower 1–3 cm of
each branch bare of spikelets; spikelets awnless, 2-flowered (the lower floret sterile, the upper
floret perfect), glabrous, 1.8–2.4 mm long, sometimes purple-stained, at maturity gaping open
at apex; glumes both present, the lower 1/3–1/2 as long as spikelet, acute; upper glume resembling
lemma of lower floret; palea of the lower (neuter) floret inflated, obovate, indurate, often
apiculate, distinctive, larger than the lemma and giving the spikelet an expanded, widely gaping
appearance; upper (perfect) floret 1.6–1.9 mm long, the lemma and palea firm, but not tough
and hard nor grain-like. Low areas, moist soils, often in shade; widespread in e 1/2 of TX; se U.S.
from VA s to FL w to OK and TX, also MO and NM. Apr–Oct, typically early in growing season.
[Panicum hians Elliott]
STENOTAPHRUM Trin. ST. AUGUSTINE GRASS
AA C4 genus of 7 species of tropical and warm areas of the world, primarily along the Indian
Ocean rim, mainly along seashores or near the coast, rarely inland; three species are endemic to
Madagascar and one is questionably native to North America (Clayton & Renvoize 1986; Allred
2003e). It has been suggested that the genus is derived from Paspalidium through a progressive
reduction of the inflorescence branches and expansion of the central axis of the inflorescence
(Sauer 1972; Clayton & Renvoize 1986). Other authorities (e.g., Webster 1988), however, disagree
and suggest it is more closely related to two Old World genera, Thuarea Pers. and
Uranthoecium Stapf. The swollen inflorescence axis has been postulated to be an adaptation to
dispersal by sea; however, it remains buoyant for only ca. a week (Sauer 1972; Clayton &
Renvoize 1986). Some species are used for pasture, for lawns, or playing fields, or are considered
significant weeds (Watson & Dallwitz 1992). (Greek: steno, narrow and taphros, trench, from
grooves in the inflorescence axis into which the reduced branches are sunken) (subfamily
Panicoideae, tribe Paniceae)
REFERENCES: Sauer 1972; Crins 1991; Allred 2003e.
Stenotaphrum secundatum (Walter) Kuntze, (with parts arranged along one side), ST. AUGUSTINE
GRASS, CARPET GRASS. Stoloniferous, sod-forming perennial; culms decumbent or ascending,
rooting at the nodes, the flowering branches ascending to ca. 30 cm tall; leaf sheaths compressed,
keeled, with a few hairs at summit; ligule a minute membrane with a very short ring of
hairs; leaf blades 5–15(–18) cm long, 5–10 mm wide, � obtuse apically; inflorescences spike-like,
usually 5–10 cm long and 5–10 mm wide, the axis wide, flattened, and corky, appearing unbranched
(cryptically a very reduced panicle with short appressed branches—each bearing 1–
3(–5) spikelets—sunken into the axis); spikelets 4–5 mm long, awnless, 2-flowered, the lower
floret staminate or neuter, the upper floret perfect, appressed and sunken into one side of the
axis; lower glume 1–2 mm long, smaller than upper glume, the second ca. as long as spikelet;
stamens 3. Commonly planted as a lawn grass, escaping locally to a limited extent; tending to
freeze back in very severe winters, particularly in the n part of East TX; Bexar, Brazos, Dallas,
Grayson, Harris (BRIT), Colorado, and Travis (Turner et al. 2003) cos.; scattered in TX w to e
Cross Timbers and Prairies and Edwards Plateau; se U.S. from VA s to FL w to MO, OK, and TX,
also CA. Jun–Aug. Native range uncertain; possibly native to the tropics (e.g., South America—
Webster 1993b) though now widespread. Webster (1988) considered it probably introduced to
the United States. However, it was known along the e coast of the U.S. before 1800 (Sauer 1972),
and recently a number of authorities (e.g., Kartesz 1999; Allred 2003e) have considered it native
to the U.S. This species is widely used as a lawn and turf grass in the tropics and subtropics
(Sauer 1972; Crins 1991), and it is also used for soil stabilization (Webster 1988). It can be an aggressively
weedy invader of flower beds where grown as a lawn; it can grow vigorously in some
shade. A variegated form is known and is sometimes used as an ornamental in hanging baskets
and greenhouses (Sauer 1972; Allred 2003e). Crins (1991) noted that diploid plants have yellow
stigmas and are capable of normal sexual reproduction, while triploid (generally used for
lawns) and tetraploid plants have purple stigmas and are sterile. ?I