Digitaria setigera Roth

synonyms: Digitaria pruriens, Syntherisma pruriens


kūkaepua‘a, itchy crabgrass, mau'u kūkaepua'a


Info

Subfamily: Panicoideae
Genus etymology: Digitaria = "having fingers" [Latin] refering to the inflorescence structure
Species etymology: setigera = "bristle bearing [Latin] refering to the bristles present on the raceme axis of the type specimen
Photosynthetic type: C4 (warm season)
Nativity: naturalized - accidental
First recorded in Hawaiʻi:

Map

 Distribution of Digitaria setigera in Hawaiʻi.
 Distribution of Digitaria setigera in Hawaiʻi.

Inflorescence

Digitaria setigera Inflorescence
Digitaria setigera Inflorescence
Digitaria setigera Inflorescence
Digitaria setigera Inflorescence

Plant

Digitaria setigera Plant

Habit

Digitaria setigera Habit
Digitaria setigera Habit
Digitaria setigera Habit

Spikelets

Digitaria setigera Spikelets
Digitaria setigera Spikelets
Digitaria setigera Spikelets
Digitaria setigera Spikelets
Digitaria setigera Spikelets
Digitaria setigera Spikelets
Digitaria setigera Spikelets

Node

Digitaria setigera Node
Digitaria setigera Node

Description

Annual; culms 20–80 cm. high, geniculately ascending from a decumbent base. Leaf-blades broadly linear to lanceolate, 3–25 cm. long, 3–12 mm. wide. Inflorescence of 3–15 racemes arranged on a common axis 1–6 cm. long, or digitate in the smaller plants; racemes 4–15 cm. long, the spikelets binate and overlapping by ± 2/3 their length on a narrowly winged triquetrous rhachis, this sometimes bearing a few long glistening hairs. Spikelets lanceolate to elliptic-lanceolate, 2–3 mm. long; lower glume absent or very obscure; upper glume 1/8–1/4 as long as the spikelet, oblong or triangular, 0– to sub–3-nerved; lower lemma as long as the spikelet, 7-nerved, the nerves evenly spaced or with a wide central interspace, appressedly or silky pubescent, rarely with a ciliate frill, very rarely with stiff bristles; fruit lanceolate, grey to yellowish brown.
(Description source: Clayton, W.D. & Renvoize, S.A. 1982. Flora of Tropical East Africa. Gramineae (Part 3). A.A. Balkema, Rotterdam. 448 pp. )

Plants of indefinite duration. Culms to 120 cm tall, bases long-decumbent and rooting at the lower nodes. Sheaths with papillose-based hairs; ligules 2.5-3.5 mm; blades 4-28 cm long, 4-12 mm wide, scabrous, usually with some scattered papillose-based hairs on the base of the adaxial surfaces, sometimes with hairs all over. Panicles with 3-11 spikelike primary branches in 1-several whorls, rachises to 6 cm; primary branches 5-15 cm, axes wing-margined, wings more than 1/2 as wide as the midribs, lower and middle portions bearing spikelets in unequally pedicellate pairs; secondary branches absent; shorter pedicels 0.3-0.8 mm; longer pedicels 1.7-2.7 mm. Spikelets 2.4-3.5 mm, homomorphic, ovate. Lower glumes absent or to 0.1 mm; upper glumes 0.2-1.3 mm, 1/6 - 1/3 as long as the spikelets, 1-3-veined, margins and apices with appressed, white hairs about 0.5 mm, truncate or bilobed; lower lemmas (5)7-veined, veins smooth or scabrous only over the distal 1/3, unequally spaced, margins and lateral intercostal regions silky-ciliate; upper lemmas tan or gray when immature, brown at maturity, acuminate; anthers 0.6-1.3 mm. 2n = 70, 72.
(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_setigera )

Annuals; culms geniculately ascending from a decumbent base, 20-80 cm tall. Sheaths sparsely to densely stiff-pubescent; ligule 1.5-3 mm long, truncate, erose; blades linear to lanceolate, 3-25 cm long, 3-12 mm wide, both surfaces moderately to densely stiff-pubescent. Inflorescences composed of 3-15 racemes arranged on a common axis, 1-6 cm long, or digitate in smaller plants, racemes 4-15 cm long; spikelets in pairs, imbricate, rachis trigonous, winged, sometimes with a few long, glistening hairs; spikelets lanceolate to elliptic-lanceolate, 2-3 mm long; (first glume absent or less than 0.3 mm long, second glume 1/8-1/4 as long as the spikelet, oblong or triangular, 0-3-nerved, margins usually arachnoid pubescent; first lemma as long as the spikelet, 7-nerved, the nerves evenly spaced or with a wide central interval, appressed pubescent or silky pubescent, rarely ciliate or with stiff bristles; palea as long as lemma. Caryopsis gray to yellowish brown, lanceolate, glabrous. [2n = 18, 36, 54, 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 )