Dichanthelium wilcoxianum
Dichanthelium aciculare
fall panicum, fall rosette grass, Wilcox's panicgrass
narrow-leaf panicgrass, needleleaf rosette grass
15-35 cm, stiffly erect, all but the upper 2-4 internodes very short;
nodes glabrous or with weak, reflexed hairs;
internodes purplish-gray, sparsely pubescent;
fall phase developing early, forming erect branches from the lower or midculm nodes, each branch terminating in a partially included panicle of 8-16 spikelets, no sterile shoots formed.
15-75 cm, erect;
nodes glabrous or sparsely pubescent;
internodes glabrous or puberulent to pilose basally;
fall phase with erect to spreading culms, extensively branched from the mid- and upper culm nodes, eventually producing flabellate clusters of reduced, flat or involute blades.
usually 3;
sheaths hirsute, hairs papillose-based;
ligules 0.5-1 mm;
blades 4-8 cm long, 2-5 mm wide, all alike, stiffly erect, green to grayish-green, flat, not plicate, sparsely pilose.
3-7;
sheaths shorter than the internodes, glabrous or with soft, ascending, papillose-based hairs;
ligules 0.5-2 mm, of hairs;
lower blades 4-16 cm long, 3-9 mm wide, stiffly ascending to erect, glabrous or sparsely pilose to pubescent, with prominent raised veins, flat or longitudinally wrinkled, blades of the flag leaves often greatly reduced, often involute.
2.4-3.2 mm long, 0.7-1.2 mm wide, ellipsoid to obovoid, often reddish throughout, short-pubescent.
1.7-3.6 mm long, 1.2-1.8 mm wide, obovoid to ellipsoid, biconvex in side view, glabrous or pubescent, bases narrow to attenuate, apices blunt or pointed to beaked.
0.7-1.2 mm, triangular;
upper glumes and lower lemmas about equaling the upper florets;
upper florets 1.9-2.5 mm, ellipsoid, pointed.
thin, weakly veined, about 1/3 as long as the spikelets, attached to 0.5 mm below upper glumes, clasping at the base, broadly triangular to rounded;
upper glumes with 5-9 prominent veins;
lower florets sterile;
upper florets apiculate.
rosettes poorly differentiated;
sheaths glabrous;
blades 2-4 cm, narrow, similar to those of the lower cauline leaves, ascending to spreading.
rosettes poorly differentiated;
blades usually large, ovate to lanceolate, often transitional to the cauline blades.
panicles 3-5 cm long, 2-4 cm wide, ovoid, open, shortly exserted, with 12-32 spikelets;
branches short, stiff, spreading;
pedicels mostly 4-8 mm, spreading.
panicles 2-10 cm long, 0.5-7 cm wide, open or contracted, well-exserted.
= 18.
= 18.
Dichanthelium wilcoxianum
Dichanthelium aciculare
Dichanthelium wilcoxianum grows in dry prairies, especially in sandy or gravelly openings. It is restricted to the Flora region. The primary panicles, which are produced from mid-May to early June, are partially open-pollinated; the secondary panicles, which are produced in June, and occasionally also in September, are cleistogamous.
Some specimens of Dichanthelium oligosanthes subsp. scribnerianum from the southern Great Plains that have prematurely elongating upper internodes resemble D. wilcoxianum, but they have greenish spikelets that are 1.7-2.4 mm wide, an orange spot at the base of the glumes, and larger basal rosettes.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Dichanthelium aciculare grows in sandy, open areas in the southeastern United States, the West Indies and the Caribbean, southern Mexico, Central America, and northern South America. It has not been reported from northern Mexico. The primary panicles are open-pollinated (sometimes briefly) and develop from April to June; the secondary panicles are cleistogamous and develop from May into late fall.
The subspecies are often distinct when growing together, perhaps maintained by the predominant autogamy, but they are more difficult to separate over wider geographic areas. Rare, partly fertile putative hybrids with Dichanthelium consanguineum, D. acuminatum, D. ovale, D. portoricense, and (possibly) D. dichotomum apparently lead to some intergradation with these species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Primary panicles usually contracted; branches appearing 1-sided; culms sparsely pubescent to almost glabrous | subsp. neurantbum |
1. Primary panicles not contracted; branches not appearing 1-sided; culms usually pubescent, at least on the lower internodes. | → 2 |
2. Spikelets 1.7-2.3 mm long, with blunt apices | subsp. aciculare |
2. Spikelets 2.4-3.6 mm long, with pointed or beaked apices. | → 3 |
3. Spikelets 2.4-3 mm long, not strongly attenuate at the base; lower glumes attached less than 0.2 mm below the upper glumes | subsp. angustifolium |
3. Spikelets 2.9-3.6 mm long, strongly attenuate at the base; lower glumes attached 0.3-0.5 mm below the upper glumes | subsp. fusiforme |
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