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

STEINCHISMA/POACEAE
1075
Sporobolus pyramidatus (Lam.) Hitchc., (pyramidal), WHORLED DROPSEED, TARGET DROPSEED.
Annual or short-lived perennial; culms 10–35(–60) cm tall; panicles 3–15(–18) cm long, becoming
pyramidal and exserted at maturity, the lower branches in whorls of usually 7–12(–rarely
more); spikelets 1.5–2 mm long. Open, disturbed sites; Navarro (BRIT), Anderson, Bastrop, Bexar,
Brazos, Hunt, and Tyler (Turner et al. 2003) cos.; widely scattered in TX, but more common in
the s part of the state; c U.S. from MO s to LA w to UT and AZ, also FL. Mar–Nov. [Agrostis
pyramidata Lam., S. patens Swallen, S. pulvinatus Swallen] While this taxon is sometimes included
in the Old World S. coromandelianus (Retz.) Kunth (e.g., Kartesz 1999; Hatch 2002), we
are following Peterson et al. (2003) in treating S. pyramidatus as a separate species. They noted,
however, that the two are morphologically “very similar … suggesting that they are related.”
Sporobolus silveanus Swallen, (for William Arents Silveus, 1875–1953, TX botanist, attorney,
and author of Texas Grasses), SILVEUS’ DROPSEED. Perennial; culms 0.7–1.2 m tall; panicles somewhat
open, 20–50 cm long, (5–)10–12(–15) cm wide; spikelets purple, (4–)4.5–7(–7.2) mm long.
Sandy soils, prairies, wet to mesic pine woodlands, forest openings; scattered in East TX in Hardin,
Jasper, Rains (BRIT), Angelina, Brazos, Harris, Lamar (Tridens Prairie), Orange, Tyler, and
Van Zandt (Weakley & Peterson 1998) cos.; also n Gulf Prairies and Marshes; w LA, se OK, and
East TX (Weakley & Peterson 1998); Peterson et al. (2003) also mapped a single county in FL
and a single county in GA. Jul–Nov. Brown (1993) concluded that all TX material previously
identified as the related species S. heterolepis (A. Gray) A. Gray was actually S. silveanus. We are
following Brown (1993) in not considering S. heterolepis to be a member of the TX flora.
Sporobolus vaginiflorus (Torr. ex A. Gray) A.W. Wood, (with flowers in the sheaths), POVERTY
DROPSEED, SOUTHERN POVERTY GRASS, POVERTY GRASS. Annual; culms 15–50(–70) cm tall;
panicles terminal and axillary, contracted, 1–5 cm long, 2–5 mm wide, usually partially enclosed
within subtending sheaths; spikelets usually 3–5(–6) mm long; lemma often mottled
with dark purple, with short appressed pubescence. Disturbed sites, roadsides, fields, sandy or
clay soils, limestone outcrops; widespread in e 1/2 of TX, scattered further w; scattered in s
Canada and throughout the e U.S. w to ND and TX, also AZ, ID, and NM. Aug–Nov. This species
is similar to and apparently related to S. ozarkanus; see discussion under that species.
Sporobolus heterolepis (A. Gray) A. Gray, PRAIRIE DROPSEED, has often been reported for TX (e.g.,
Correll & Johnston 1970; Gould 1975; Hatch et al. 1990). Brown (1993), however, concluded that
all TX material identified as this species was actually S. silveanus. We are following Brown
(1993), Hatch (2002), and Turner et al. (2003) in considering S. heterolepis not to be a member
of the TX flora. However, several old collections are still listed incorrectly as S. heterolepis on
the Digital Flora of Texas Herbarium Specimen Browser (2002) and were apparently picked up
in the recent Flora of North America treatment (Peterson et al. 2003).
STEINCHISMA Raf. GAPING PANIC GRASS
AA New World genus of 5–6 species of tropical to warm-temperate regions, growing typically in
moist or wet, usually open, sandy areas (Freckmann & Lelong 2003c). It has traditionally been
included in Panicum (e.g., Correll & Johnston 1970; Hatch et al. 1990), sometimes in the subgenus
Steinchisma (Zuloaga 1987). Recent studies (e.g., Zuloaga et al. 2000) support its recognition
as a separate genus (Freckmann & Lelong 2003c). Photosynthesis is intermediate between
that of C3 and C4 plants (Freckmann & Lelong 2003c). (Greek: steinos, narrow, and chasma,
yawning, presumably in reference to the gaping glumes and somewhat narrow spikelets when
compared to Panicum—Freckmann & Lelong 2003c) (subfamily Panicoideae, tribe Paniceae)
REFERENCES: Zuloaga et al. 1992, 1998. Freckmann & Lelong 2003c.
Steinchisma hians (Elliott) Nash, (gaping), GAPING PANICUM, GAPING GRASS, GAPING PANIC GRASS.
Perennial with culms erect or decumbent at base, to 75 cm tall; nodes glabrous or scabrous; leaf
sheaths glabrous or with hairs on upper margins; ligule a short membrane ca. 0.5 mm long; leaf