Digitaria ciliaris (Retz.) Koeler

synonyms: Digitaria sanguinalis [misapplied in Hawai'i], Syntherisma debilis [misapplied in Hawai'i]


tropical crabgrass, kūkaepua‘a


Info

Subfamily: Panicoideae
Genus etymology: Digitaria = "having fingers" [Latin] refering to the inflorescence structure
Species etymology: ciliaris = "ciliate" [Latin] refering to the hairs on the lower lemma
Photosynthetic type: C4 (warm season)
Nativity: naturalized - accidental
First recorded in Hawaiʻi: 1864

Map

 Distribution of Digitaria ciliaris in Hawaiʻi.
 Distribution of Digitaria ciliaris in Hawaiʻi.

Inflorescence

Digitaria ciliaris Inflorescence
Digitaria ciliaris Inflorescence
Digitaria ciliaris Inflorescence
Digitaria ciliaris Inflorescence
Digitaria ciliaris Inflorescence
Digitaria ciliaris Inflorescence
Digitaria ciliaris Inflorescence

Plant

Digitaria ciliaris Plant
Digitaria ciliaris Plant
Digitaria ciliaris Plant

Habit

Digitaria ciliaris Habit
Digitaria ciliaris Habit
Digitaria ciliaris Habit
Digitaria ciliaris Habit

Spikelets

Digitaria ciliaris Spikelets
Digitaria ciliaris Spikelets
Digitaria ciliaris Spikelets
Digitaria ciliaris Spikelets
Digitaria ciliaris Spikelets
Digitaria ciliaris Spikelets

Description

Annual; culms 20–100 cm. high, decument at the base and geniculately ascending. Leaf-blades broadly linear, 3–25 cm. long, 3–10 mm. wide. Inflorescence digitate or subdigitate (axis up to 5 cm. long in robust specimens), composed of 2–12 racemes; racemes stiff, 6–22 cm. long, sometimes adorned with sparse long white hairs, the spikelets binate and overlapping by about 2/3 of their length on a winged rhachis with triquetrous midrib. Spikelets narrowly elliptic, (2–)2.5–3.3(–3.7) mm. long, sharply acute; lower glume distinct, typically 0.2–0.4 mm. long and triangular; upper glume (1/2–)2/3–3/4 as long as the spikelet, 3-nerved; lower lemma as long as the spikelet, 7-nerved, the nerves smooth and evenly spaced or with a wide interspace flanking the midrib (sometimes those of the subsessile spikelet evenly and of the pedicelled spikelet unevenly spaced), appressed puberulous, silky pubescent or rarely shortly villous, often encompassed by a ciliate frill, sometimes the pedicelled or both spikelets beset with stiff glassy yellowish bristles; fruit ellipsoid, grey to light brown.
(Description source: Clayton, W.D. & Renvoize, S.A. 1982. Flora of Tropical East Africa. Gramineae (Part 3). A.A. Balkema, Rotterdam. 448 pp. )

Annual up to 100 cm high, often decumbent at the base and geniculately ascending; leaves broadly linear. Inflorescence of 2–12 digitate or subdigitate racemes, the axis up to 5 cm long in robust specimens; racemes stiff, 6–22 cm long, the spikelets in pairs and overlapping by 2/3 their length on a winged rhachis with triquetrous midrib. Spikelets narrowly elliptic, 2.5–3.3(–3.7) mm long, sharply acute; lower glume a distinct triangular scale usually 0.2–0.4 mm long; upper glume (1/2–)2/3–3/4 the length of the spikelet, 3-nerved; lower lemma 7-nerved, the nerves smooth and evenly spaced or with a wide interspace flanking the midrib (sometimes the spikelets of a pair different), appressed-puberulous to silky-pubescent or rarely shortly villous, often with aciliate frill, sometimes one or both spikelets of a pair beset with glassy bristles; fruit ellipsoid, grey to light brown.
(Description source: Cope, T.A, (1995) Flora Somalia, Vol 4. Royal Botanical Gardens, Kew, London. 312 pp. )

A loosely caespitose or solitary growing annual. Culms 20–60 cm., decumbent to ascending, glabrous, nodes dark and (sub)glabrous. Leaf sheaths scaberulous, sometimes with a few bulbous based bristles. Ligule up to 2.5 mm. long, truncate, erose. Leaf laminae 4–13 × 0.3–0.8 mm., linear, flat, scaberulous on both sides, with a few bulbous based bristles near the base, scabrous along the margin. Inflorescence composed of 2–9 racemes, 6–12 cm. long, in 1 or 2-more superposed whorls, sometimes a few solitary along the short common axis. Rhachis triquetrous, winged, up to 1.0 mm. broad, smooth with scabrous margins. Pedicels 2-nate, 0.5–2.5 mm. long, triangular, scabrous, scarcely broadened at the apex. Spikelets 2.7–3.4 mm. long, oblonglanceolate. Inferior glume c. 0.5 mm. long, ovate to oblong triangular, often somewhat truncate. Superior glume 2/3–3/4 of the spikelet, oblong triangular, 3-nerved, appressed hairy, hairs very fine, smooth, acute. Inferior lemma as long as the spikelet, oblong-lanceolate, 7-nerved, nerves smooth or nearly smooth, central zone often very broad, appressed hairy, sometimes also with bristle-hairs, rarely glabrous. Superior glume as long as to somewhat shorter than the spikelet, oblong-lanceolate, acute, pale yellow to pale brown, often purplish tinged.
(Description source: Launert, E. & Pope, G.V. (eds.). 1989. Flora Zambesiaca. Volume 10. Part 3. Kew, London. 152 pp. )

Plants annual or of indefinite duration. Culms 10-100 cm long, erect portion 30-60 cm, long-decumbent, rooting and branching at the decumbent nodes, sparingly branched or unbranched from the upper nodes; nodes 2-5, glabrous. Sheaths with papillose-based hairs; ligules 2-3.5 mm, erose; blades 1.5-14.4(18.9) cm long, 3-9 mm wide, flat, glabrous, a few scattered papillose-based hairs at the base of the adaxial surfaces (occasionally over the whole adaxial surface), usually also scabrous on both surfaces. Panicles with 2-10 spikelike primary branches, these digitate or in 1-3 whorls on rachises to 2 cm; lowest panicle nodes with hairs more than 0.4 mm; primary branches 3-24 cm long, 0.6-1.2(2) mm wide, glabrous or with less than 1 mm hairs, axes wing-margined, wings at least 1/2 as wide as the midribs, lower and middle portions of the branches bearing spikelets in unequally pedicellate pairs; secondary branches absent; shorter pedicels 0.5-1 mm; longer pedicels 1.5-4 mm. Spikelets (2.7)2.8-4.1 mm long, homomorphic. Lower glumes 0.2-0.8 mm, acute; upper glumes (1.2)1.5-2.7 mm, about 2/3 to almost as long as the spikelet, 3-veined, margins and apices pilose; lower lemmas 2.7-4.1 mm, 7-veined, veins unequally spaced, outer 3 veins crowded together near each margin, well-separated from the midvein, usually smooth, occasionally the lateral veins scabridulous on the distal 1/3 margins and regions between the 2 inner lateral veins hairy, hairs 0.5-1 mm (rarely glabrous), sometimes also with glassy yellow hairs between the 2 inner lateral veins, these more common on the upper spikelets; upper lemmas 2.5-4 mm, glabrous, yellow, tan, or gray when immature, becoming brown, often purple-tinged (occasionally completely purple) at maturity; anthers 0.6-1 mm. 2n = 54.
(Description source: Barkworth, M.E., Capels, K.M., Long, S. & Piep, M.B. (eds.) 2003. Flora of North America, north of Mexico. Volume 25. Magnoliophyta: Commelinidae (in part): Poaceae, Part 2. Oxford University Press, New York. 783 pp http://floranorthamerica.org/Digitaria_ciliaris )

Annuals; culms decumbent at base and geniculately ascending, 20-100 cm long. Sheaths variously covered with bulbous-based hairs, becoming glabrous apically; ligule 1-3 mm long, truncate to rounded, erose; blades linear, 3-25 cm long, 3-10 mm wide. Inflorescence composed of 2-12 racemes, digitately or subdigitately arranged, the axis up to 5 cm long, racemes stiff, 6-22 cm long, sometimes sparsely covered with long white hairs, axis trigonous, winged; spikelets in pairs, imbricate, narrowly elliptic, (2-)2.5-3.3(-3.7) mm long, sometimes the pedicellate or both spikelets with stiff yellowish bristles, apex sharply acute; first glume triangular, usually 0.2-0.4 mm long, second glume (1/2)2/3-3/4 as long as the spikelet, 3-nerved; first lemma as long as the spikelet, 7-nerved, the nerves smooth and evenly spaced or with a wide interval flanking the midnerve, appressed puberulent, silky pubescent or rarely short-villous, usually ciliate, second lemma narrowly ovate, ca. 2.8 mm long, hyaline, 3-nerved, glabrous; palea similar in shape and texture to lemma, ca. 2.8 mm long, 2-nerved, clasped by the lemma. Caryopsis gray to pale brown, ellipsoid. [2n = 18, 36, 54, 60, 68, 70, 72.]
(Description source: O’Connor, P.J. 1990. Poaceae, pp. 1481–1604. In: Wagner W.L., Herbst D.R. & Sohmer S.H. (eds.)., Manual of the flowering plant of Hawaiʻi. Vol. 2. University of Hawaii Press & Bishop Museum Press, Honolulu )