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

916 POACEAE/DISTICHLIS
smaller spikelets and more densely pubescent leaf blades; culms weak, rooting at nodes; leaf
sheaths and blades pubescent with papilla-based hairs; inflorescence usually with 4–9(–13)
branches often 6–15 cm long, sometimes longer, these digitately arranged or nearly so (sometimes
in 2–3 whorls along a short main axis); lemma of lower floret 7-veined (sometimes apparently
5-veined), the lateral veins minutely scabrous above; 2n = 36 (Gould 1975b). Open disturbed
areas, much less common in East TX than D. ciliaris; widely scattered in TX; s Canada
and throughout most of the U.S. Jul–Nov. Native of Eurasia. This species is considered a serious
weed in some areas (Yatskievych 1999) and is listed by some sources among the world’s worst
weeds (Holm et al. 1977). � I
Digitaria texana Hitchc., (of Texas), TEXAS CRAB GRASS, TEXAS FINGER GRASS. Perennial; culms to 80
cm long, decumbent at base, often stoloniferous and rooting at the nodes; inflorescence branches
usually 4–12, typically along a short axis; spikelets 2–2.6 mm long (not including coastal form
with longer spikelets, mentioned below); upper glume and lemma of lower floret pubescent marginally
and sometimes on back. Sandy soils, prairies, roadsides, sandy oak woods; tentatively included
based on citation for the Big Thicket National Preserve (National Park Service 1995a,
1995b); no East TX specimen seen; found primarily to the s of East TX in the Gulf Prairies and
Marshes and adjacent South TX Plains; according to Webster and Hatch (1990), the species occurs
near the TX coast from Calhoun Co. to Cameron Co.; they also cited a Brazos Co. record (Reeves
1040, TAES) but suggested it “probably represents an incorrectly labeled specimen;” endemic to
TX (Carr 2002b, 2002c) or possibly also in FL (Wipff 2003f); no county distribution map is provided.
Sep–Nov. [D. runyonii Hitchc.] A form of this species occurring on coastal sand dunes has
longer spikelets (ca. 2.8–3.3 mm long). It was previously recognized as D. runyonii (e.g., Gould
1975b), but subsequent research (Webster & Hatch 1990) found that vegetative characters overlap,
intermediates are common, and “D. runyonii is best placed in synonymy under D. texana.” E
Digitaria violascens Link, (becoming violet), VIOLET CRAB GRASS. Tufted annual to 60 cm tall;
similar to D. ischaemum, except spikelets smaller (see key); upper glume from 1/2 to almost as
long as lemma of upper floret; 2n = 36 (Gould 1975b). Partial shade, forest margins, openings in
pine or mixed forests, disturbed areas; s part of the Pineywoods and Post Oak Savannah; also
Denton Co. (Turner et al. 2003) in Cross Timbers and Prairies and n Gulf Prairies and Marshes;
se U.S. from NC s to FL w to TX, also NY. (Jun–)Aug–Nov. Native of the Old World tropics. [D.
chinensis (Nees) A. Camus, D. ischaemum (Schreb.) Muhl. var. violascens (Link) Radford] Some
authors question whether this species is specifically distinct from D. ischaemum (e.g., Allen
1992b) or is a variety of that species (e.g., Radford et al. 1968). I
DISTICHLIS Raf. SALT GRASS, ALKALI GRASS
AA genus of 5 species (Barkworth 2003a), 4 in the New World, 1 in Australia; typically of seashores
and deserts. It is apparently related to Monanthochloe, and intergeneric hybrids between
the two have been reported (Stephenson 1972). Distichlis species are halophytic (= adapted to
grow in saline or alkali soils) and have salt glands, specialized epidermal structures for the excretion
of excess salts from leaf tissue (Oross & Thomson 1982). They are also characterized by
C4 photosynthesis, an advantage in arid environments (Watson & Dallwitz 1992). (Greek:
distichos, two-ranked) (subfamily Chloridoideae, tribe Cynodonteae)
REFERENCES: Beetle 1955; Peterson et al. 1997; Barkworth 2003a.
Distichlis spicata (L.) Greene, (with spikes), SALT GRASS, SPICATE SALT GRASS, INLAND SALT GRASS,
DESERT SALT GRASS, COASTAL SALT GRASS, SPIKE GRASS, ALKALI GRASS. Low glabrous perennial 10–
35(–70) cm tall from extensive scaly rhizomes, usually dioecious; flowering culms erect, the internodes
short, with leaf sheaths conspicuously overlapping at least on lower portion of culm;
leaves noticeably distichous (= 2-ranked); ligule a minute membrane � 0.5 mm long; leaf blades
2–20 cm long, 1–3 mm wide, often � involute; inflorescence a contracted spike-like panicle or
spike-like raceme 3–8 cm long; spikelets pedicellate, � similar on male and female plants, usually