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blunt-glumed panicgrass

cypress panicgrass, fork panic grass, fork rosette-panicgrass

Habit Plants usually densely cespitose. Plants in small or large clumps, with knotty crowns.
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.

20-100 cm, decumbent to erect, sometimes geniculate;

nodes usually glabrous, sometimes sparsely pilose or densely bearded with retrorse hairs;

internodes often purplish or olive green, lowest internodes usually glabrous, varying to sparsely pubescent;

fall phase usually branching freely, especially from the nodes above the middle, ultimately forming dense, reclining fascicles of divergent branchlets with numerous reduced, thin, often involute blades, secondary panicles often reduced, with few spikelets.

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.

4-7;

sheaths usually shorter than the internodes, usually glabrous, occasionally the lower sheaths sparsely to densely soft-pubescent, sheaths of the uppermost leaves sometimes with whitish glandular spots between the prominent veins, margins of all sheaths glabrous or ciliate;

ligules absent or shorter than 1 mm, of hairs;

blades 3.5-14 cm long, 5-14 mm wide, usually thin, distant, spreading to reflexed or (occasionally) ascending, yellow-green to purplish, usually glabrous on both surfaces or (at least the lower blades) more or less densely and softly pubescent, bases constricted (in narrow-bladed subspecies) or narrowly subcordate (in wide-bladed subspecies), margins glabrous or ciliate basally, glabrous distally, blades of the flag leaves usually spreading.

Spikelets

1.5-2.6 mm, obovoid-pyriform, planoconvex in side view, puberulent, pubescent, or glabrous, attenuate basally, apices usually broadly rounded.

1.5-2.7 mm, usually ellipsoid or obovoid, green or purplish (at least at the base), glabrous or (less commonly) sparsely pubescent or puberulent, often prominently veined, obtuse to acute to beaked.

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.

usually less than 1/3 as long as the spikelets, obtuse to acute;

upper glumes usually slightly shorter than or as long as the lower lemmas and upper florets (occasionally extending beyond the floret);

lower florets sterile;

upper florets 1.3-2 mm long, usually less than 1 mm wide, ellipsoid, subacute to obtuse.

Basal

rosettes well-differentiated;

blades 1.5-6 cm, ovate to lanceolate.

rosettes well-differentiated;

blades ovate to lanceolate.

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.

panicles 3-12 cm, long-exserted, usually with many spikelets;

branches wiry, mostly spreading or ascending, usually glabrous, sometimes scabridulous.

2n

= 18.

Dichanthelium portoricense

Dichanthelium dichotomum

Distribution
from USDA
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KY; LA; MA; MD; ME; MI; MN; MO; MS; NC; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV; PR; NB; ON
[WildflowerSearch map]
[BONAP county map]
Discussion

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Dichanthelium dichotomum grows in dry, sandy, clayey, or rocky ground, often in woods, or (more commonly) in moist or wet places, including marshes, bogs, low woods, swamps, and the moist borders of lakes and ponds. Its range extends south from the Flora region into the Caribbean. It is a polymorphic and ubiquitous species, with many of its intergrading subspecies exhibiting traits of other widespread and variable species such as D. commutatum, D. laxiflorum, and D. sphaerocarpon, which often grow at the same sites.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Spikelets 1.8-2.6 mm long, usually densely pubescent or puberulent (rarely glabrous); cauline blades 4-7 cm long, 3.5-8 mm wide
subsp. patulum
1. Spikelets 1.5-2.0 mm long, puberulent to nearly glabrous; cauline blades 2-5 cm long, 2.5-4.5 mm wide
subsp. portoricense
1. Lower nodes hairy.
→ 2
2. Spikelets 1.5-1.8 mm long, upper floret 0.6-0.8 mm wide
subsp. microcarpon
2. Spikelets 1.8-2.5 mm long; upper floret 0.7-1.0 mm wide.
→ 3
3. Spikelets usually glabrous; midculm blades usually 5-7 mm wide
subsp. dichotomum
3. Spikelets pubescent; midculm blades usually 7-14 mm wide.
→ 4
4. Lower sheaths and blades glabrous or sparsely pubescent
subsp. nitidum
4. Lower sheaths and blades more or less densely velvety pubescent
subsp. mattamuskeetense
1. Lower nodes glabrous.
→ 5
5. Larger blades more than 1 cm wide; sheaths often with pale glandular spots between the prominent veins; spikelets 1.9-2.6 mm long, acute to beaked
subsp. yadkinense
5. Larger blades less than 1 cm wide; sheaths without glandular spots; spikelets 1.5-2.3 mm long, obtuse to subacute.
→ 6
6. Culms weak, ultimately reclining or sprawling, often flattened
subsp. lucidum
6. Culms erect, terete.
→ 7
7. Blades usually spreading; spikelets ellipsoid, 1.8-2.3 mm long, rarely purplish at the base
subsp. dichotomum
7. Blades usually ascending or erect; spikelets broadly ellipsoid or obovoid, 1.5-1.8 mm long, often purplish at the base
subsp. roanokense
Source FNA vol. 25, p. 441. FNA vol. 25, p. 432.
Parent taxa Poaceae > subfam. Panicoideae > tribe Paniceae > Dichanthelium > sect. Lancearia Poaceae > subfam. Panicoideae > tribe Paniceae > Dichanthelium > sect. Dichanthelium
Sibling taxa
D. aciculare, D. acuminatum, D. boreale, D. boscii, D. chamaelonche, D. clandestinum, D. commutatum, D. consanguineum, D. depauperatum, D. dichotomum, D. ensifolium, D. erectifolium, D. latifolium, D. laxiflorum, D. leibergii, D. linearifolium, D. malacophyllum, D. nodatum, D. nudicaule, D. oligosanthes, D. ovale, D. pedicellatum, D. perlongum, D. polyanthes, D. ravenelii, D. scabriusculum, D. scoparium, D. sphaerocarpon, D. strigosum, D. tenue, D. wilcoxianum, D. wrightianum, D. ×anthophysum
D. aciculare, D. acuminatum, D. boreale, D. boscii, D. chamaelonche, D. clandestinum, D. commutatum, D. consanguineum, D. depauperatum, D. ensifolium, D. erectifolium, D. latifolium, D. laxiflorum, D. leibergii, D. linearifolium, D. malacophyllum, D. nodatum, D. nudicaule, D. oligosanthes, D. ovale, D. pedicellatum, D. perlongum, D. polyanthes, D. portoricense, D. ravenelii, D. scabriusculum, D. scoparium, D. sphaerocarpon, D. strigosum, D. tenue, D. wilcoxianum, D. wrightianum, D. ×anthophysum
Subordinate taxa
D. portoricense subsp. patulum, D. portoricense subsp. portoricense
D. dichotomum subsp. dichotomum, D. dichotomum subsp. lucidum, D. dichotomum subsp. mattamuskeetense, D. dichotomum subsp. microcarpon, D. dichotomum subsp. nitidum, D. dichotomum subsp. roanokense, D. dichotomum subsp. yadkinense
Synonyms Panicum portoricense Panicum niditum, Panicum dichotomum var. barbulatum, Panicum dichotomum
Name authority (Desv. ex Ham.) B.E Hansen & Wunderlin (L.) Gould
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