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.

Perennial herb, tufted 15 cm - 1 m tall

Inflorescence: a terminal, branched arrangement of spikelets (panicle). Primary panicles atop the culms, often open, rather dense, 3 - 12 cm long, one-fourth to three-fourths as wide as long, well-exserted. Secondary panicles (when present) atop the branches.

Fruit: a caryopsis, indehiscent, enclosed within the persistent lemma and palea.

Culm: upright to ascending, 15 cm - 1 m long, round in cross-section, hollow, minutely hairy. Nodes sometimes swollen, minutely hairy. Fall phase decumbent or spreading, branching from most of the nodes.

Spikelets: 1.5 - 2 mm long, broadly ellipsoid or reverse egg-shaped with a blunt to nearly pointed apex, minutely hairy.

Basal leaves: in a rosette. Blades shortly egg-shaped to lance-shaped, distinct from stem blades.

Stem leaves: four to seven, alternate, two-ranked. Sheaths usually shorter than internodes (about half as long at mid-culm), hairy (hairs under 3 mm long). Ligules 1 - 1.5 mm long, composed of hairs. Blades more or less firm, frequently ascending, distinctly longer and narrower than basal leaves, 3 - 7 cm long, 3 - 7 mm wide, lance-shaped with a rounded or almost heart-shaped base, parallel-veined, nearly hairless to densely hairy beneath, sometimes sparsely soft-hairy near the base above, marginally whitish and minutely rough.

Glumes:: Lower glumes usually one-fourth to one-half as long as spikelets, blunt to pointed at the apex. Upper glumes rounded to pointed at the apex.

Lemmas:: Lower lemmas similar to upper glumes. Upper lemmas longitudinally lined, shiny, with rolled-up margins above.

Paleas:: Lower paleas shorter than lower lemmas, thin. Upper paleas longitudinally lined.

Florets:: Lower florets sterile. Upper florets bisexual, stalkless, 1 - 1.5 mm long, 0.5 - 1 mm wide, ellipsoid with a blunt to pointed apex, plump. Anthers three. Stigmas red.

Similar species: No information at this time.

Flowering: June to mid-September

Habitat and ecology: Frequent in the eastern counties of the Chicago Region in dry, sandy soil.

Occurence in the Chicago region: native

Etymology: Dichanthelium comes from the Greek words di, meaning twice, and anth, meaning flowering, referring to plants that may have two flowering periods. Acuminatum means "tapering to a long point." Columbianum means "of the District of Columbia."

Author: The Morton Arboretum

My only specimens are from the H. H. Peele woods about a mile and a half southwest of Knox, Starke County. They were found in dry, sandy soil in a flat, black and white oak woods where they were closely associated with Panicum Deamii. In 1938 I found it in Steuben County. [Deam recognizes Panicum tsugetorum, which in modern treatments belongs to Dichanthelium acuminatum subsp. columbianum. It has slightly longer spikelets. He says:] this is another Panicum which is restricted to the northern part of the state and is found in dry, sandy or gravelly soils on wooded slopes and dunes. It is included by some authors with Panicum columbianum Scribn.

Much like no. 23 [Panicum columbianum Scribn.], and likewise with bistratal pubescence, but often only sparsely hairy or in part glabrous; blades ciliate at least toward the base, those of the midstem often over 6 cm; primary panicles avg larger, often over 6 cm; spikelets finely hairy to subglabrous, 1.9-2.5 mm, the first glume nearly or quite half as long, obtuse to truncate; autumnal phase copiously branched from the lower and middle nodes, forming dense mats, the blades crowded, much reduced, involute, the panicles reduced and concealed among the lvs; 2n=18. Pine woods; coastal plain from se. Va. to Fla., Miss., and Cuba. (P. nashianum; P. patulum, the form with hairy lvs; Dichanthelium sabulorum var. patulum) Perhaps properly to be subordinated to P. portoricense Desv. ex Ham. along with no. 23.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.

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.

©The New York Botanical Garden. All rights reserved. Used by permission.