Plants usually densely cespitose. Basal rosettes well-differentiated;
blades 1.5-6 cm, ovate to lanceolate. Culms 15-50 cm, slender,
wiry; internodes olive green to purplish, densely puberulent or glabrous;
fall phase spreading or decumbent, branching extensively from the lower
and midculm nodes, producing numerous congested fascicles of reduced, flat or
involute blades and reduced secondary panicles. Cauline leaves 4-7; sheaths
much shorter than the internodes, densely crisp-puberulent, velvety-puberulent,
or glabrous, often ciliate along the margins; ligules shorter than 0.5
mm; blades 2-7 cm long (seldom longer), 2.5-8 mm wide (rarely wider),
spreading, firm, flat or slightly involute, without prominently raised veins,
not longitudinally wrinkled, densely puberulent or glabrous abaxially, glabrous,
sparsely puberulent, or pubescent adaxially, bases subcordate, with papillose-based
cilia, margins often whitish and scabridulous. Primary panicles 2-7 cm
long, 2/3 to nearly as wide as long, with relatively few spikelets, exserted;
branches flexuous, spreading or reflexed, scabridulous to densely puberulent.
Spikelets 1.5-2.6 mm, obovoid-pyriform, planoconvex in side view, puberulent,
pubescent, or glabrous, attenuate basally, apices usually broadly rounded. Lower
glumes 0.6-1.4 mm, thin, weakly-veined, attached about 0.2 mm below the
upper glumes, clasping at the base; upper glumes as long as or slightly
shorter than the lower lemmas; upper florets 1.4-2 mm, broadly ellipsoid,
apices subacute, minutely puberulent. 2n = 18.
Dichanthelium portoricense grows in sandy woods, low pinelands, savannahs,
and coastal sand dunes, usually in moist places. Its range extends south from
the Flora region into Mexico, the Caribbean, and Mesoamerica. It is a
highly variable species with numerous intergrading forms, some possibly resulting
from hybridization with other widespread species in the same region, such as
D. sphaerocarpon and D.
commutatum.
Culms clustered, erect or ascending, often purplish, densely short-pubescent with minute hairs 0.1-0.4 mm, and generally with some intermingled longer hairs (often 1 mm) toward the summit of the lower internodes; sheaths likewise with bistratal pubescence; ligule a band of hairs 0.5-1.5 mm; blades 1-7 cm נ3-7 mm (those of the midstem commonly 2-5 cm), glabrous above or with a few widely scattered hairs, minutely puberulent beneath; primary panicle ovoid, mostly 2.5-4 cm, its axis puberulent; spikelets finely hairy, oblong-ovoid, obtuse, 1.3-1.9 mm, the first glume triangular-ovate, two-fifths as long; autumnal phase spreading or decumbent, branched early from most of the nodes, the blades scarcely reduced, the panicles smaller, surpassed by the lvs; 2n=18. Moist or dry, especially sandy soil; Me. to Minn., s. to Va., Tenn., and Ill. (P. oricola; P. tsugetorum; Dichanthelium c.; D. sabulorum var. thinium) Perhaps properly to be subordinated to P. acuminatum Sw.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.