Digitaria
orbata Hughes Bull. Misc. Inform. Kew 1923: 312 (1923)
T: Queensland, Herbert's
Creek, Bowman s.n. (holo K [photo BRI]; iso: BRI, MEL).
Illustrations: Henrard
(1950: 508); Tothill &.Hacker (1983: 194, fig 18).
Perennial,
rhizomatous. Flowering culms caespitose, 40–85 cm tall, 3–5-noded. Leaves:
sheaths glabrous; ligule 1.6–4 mm long; blades flat, 6–25 cm long, 1.8–5.5 mm
wide, glabrous, scabrous. Inflorescence 2–14 cm long, on a distinct central axis;
racemes 2–10, usually bearing spikelets to base, not long and rigid, 7–16 cm
long. Pedicels 0.4–0.8 mm long. Spikelets 30–70 on a typical lowermost primary
branch, hairy or rarely glabrous, paired, elliptic, 1.3–1.8 mm long, 0.47–0.8
mm wide. Lower glume absent; upper glume 0.2–0.6 mm long, less than half the
length of spikelet, ovate to elliptic, nerveless, glabrous, rounded to truncate
or cleft. Lower floret: lemma 1.1–1.6 mm long, glabrous or occasionally with a
few villous hairs on the area between the last lateral nerve and margin, 3–5-nerved; palea vestigial to absent.
Upper floret overtopping the lower floret or subequal to the lower floret;
lemma 1.2–1.7 mm long, brown, cartilaginous, muricate, elliptic, apically
rounded to acute, apiculate.
Additional specimens examined: Queensland: COOK DISTRICT: Mount
Mulligan, Apr 1985, Clarkson 5883 (BRI,
MEL, QRS, PERTH); NORTH KENNEDY DISTRICT: Dunk Is., Aug. 1951, Blake 18875
(BRI, CANB); SOUTH KENNEDY DISTRICT: Along the Collinsville-Mt Coolon Rd, 800m
southwest of its junction with Caves Creek, Jan 1996, Pollock 299 & Champion (BRI, CANB); LEICHHARDT DISTRICT: Humboldt
S of Blackwater, Jan 1997, Fensham 2981 (BRI);
PORT CURTIS DISTRICT: Dawes Range, Apr 1937, White 10813 (BRI). MITCHELL
DISTRICT: 93km N of Langlo crossing,
July 1975, Beeston 1356C (BRI);
WARREGO DISTRICT: Mt. Brandon Station, Apr 1936, Blake 11149 (BRI, CANB, DNA, PERTH); BURNETT DISTRICT: near Durong, May 1940, Blake
14245 (BRI, CANB). DARLING DOWNS DISTRICT: Palardo, Feb 1935, Blake 7640 (BRI).
Distribution and
habitat: Digitaria
orbata is broadly sympatric with D.
fumida in tropical and subtropical Queensland (Map 7) where it grows in a range of woodlands on a variety of
soils.
Phenology: Flowering
March to August.
Notes: This species
differs from Digitaria fumida only by lacking a lower glume. In AusGrass (Sharp & Simon 2002) there
are a couple of errors of illustrations from Wheeler et al. (1990) with attribution to the wrong species. The
illustration under D. orbata is D. ischaemum and
the one under D. hystrichoides is D. orbata. D. orbata does not occur in New South Wales and the
record by Jacobs et al. (2008) refers to D. diminuta.
