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

DIGITARIA/POACEAE
909
2. Main axis and branches of inflorescence (where visible below spikelets) finely pubescent;
sessile spikelets usually 4–5 mm long, with lower glumes obovate or nearly so and ca. 1.5–2
mm wide ____________________________________________________________________ D. aristatum
Dichanthium annulatum (Forssk.) Stapf, (ringed, ring-like), KLEBERG’S BLUESTEM, RINGED
DICHANTHIUM. Perennial similar to D. aristatum; culms both erect and stoloniferous, the stoloniferous
ones to 1+ m long; inflorescence with 2–9 spicate branches; lemma of sessile spikelets
with awn 1.3–2.2 cm long. Introduced as a forage grass, disturbed areas; Brazos, Goliad, Fayette,
Hays, and Travis (Turner et al. 2003) cos.; mainly Gulf Prairies and Marshes, scattered elsewhere;
FL, OK, and TX (Barkworth 2003k). Flowering throughout the growing season.
[Andropogon annulatus Forssk.] Native of se Asia. This species superficially resembles
Bothriochloa ischaemum var. songarica (KING RANCH BLUESTEM) but has much longer and more
conspicuous lemma awns. According to Gould (1975b), the inflorescence pubescence character
used in the key to species above, “is the only consistent morphological difference between” D.
annulatum and D. aristatum. KLEBERG’S BLUESTEM is regarded in some areas as a “highly esteemed
forage grass, especially in India” (Barkworth 2003k), but it is reported by Hatch et al.
(1999) to be poor forage for livestock and wildlife. It is also considered to be a significant weed
(Watson & Dallwitz 1992). I
Dichanthium aristatum (Poir.) C.E. Hubb., (with a stiff awn or bristle), ANGLETON’S BLUESTEM,
AWNED DICHANTHIUM. Perennial; culms both erect and stoloniferous, the erect culms usually
70–100 cm tall, the stoloniferous ones often longer (2+ m); inflorescence with (2–)3–5(–8) spicate
branches; lower glume of sessile spikelets with hairs, particularly near base and along
margins, the hairs 2 mm or less long; awn of lemma of sessile spikelets ca. 1.5–2.5 cm long. Introduced
as a forage grass, roadsides, disturbed areas, pastures; Goliad, Hays (BRIT), Austin,
Bastrop, Bexar, Brazos, Fayette, Travis (TAES), Caldwell, and Wilson (Turner et al. 2003) cos. in s
part of East TX; also Gulf Prairies and Marshes and South TX Plains; FL, LA, and TX. Sep–Dec.
Native in tropical and subtropical regions from India to Indonesia, widely introduced elsewhere.
[Andropogon aristatum Poir.] This species can be mistaken for Bothriochloa ischaemum, which
does not always show the grooved pedicels typicial of Bothriochloa. The pubescent inflorescence
axis and branches distinguish D. aristatum. It is reported to be poor forage for livestock
and wildlife (Hatch et al. 1999). It is also sometimes used as a lawn grass (Barkworth 2003k), but
is considered by some authorities to be a significant weed (Watson & Dallwitz 1992). I
Dichanthium sericeum (R. Br.) A. Camus, (silky), SILKY BLUESTEM, QUEENSLAND BLUESTEM,
QUEENSLAND BLUEGRASS. Tufted perennial; culms erect, usually 50–120 cm tall; inflorescence
with 2–7 branches, the spikelets with so much silky pubescence that the inflorescences appear
conspicuously silky-hairy at arm’s length; sessile spikelets 2.5–4.5 mm long; lower glumes with
hairs forming irregular line near tip, these hairs ca. 3–5 mm long and papilla-based; lemma of
sessile spikelets with awn 2–3.5 cm long. Introduced to TX as a potential forage grass (Gould
1975b); Caldwell (TAES), Brazos, and Goliad (TAMU) cos.; mainly Gulf Prairies and Marshes
and South TX Plains, also Kendall Co. (Turner et al. 2003) in e Edwards Plateau; FL and TX.
May–Sep(–late fall). [Andropogon sericeus R. Br.] Native of Australia. Hatch et al. (1999) reported
this species to be fair to poor forage for livestock and wildlife, while Watson and Dallwitz (1992)
considered it to be an important pasture species. I
DIGITARIA Haller CRAB GRASS, FINGER GRASS
Annuals or perennials; ligule membranous; inflorescence often digitate or nearly so, sometimes
with branches along a short axis, the branches few to numerous, unbranched, spike-like,
winged or unwinged, appearing 1-sided, the spikelets appressed in 2 rows along 1 side of the
branch axis OR the inflorescences appearing very different in D. cognata which has an open,
much-branched panicle with solitary long-pedicelled spikelets; spikelets sometimes in pairs (1