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fall panicum, fall rosette grass, Wilcox's panicgrass

blunt-glumed panicgrass

Habit Plants cespitose. Plants usually densely cespitose.
Culms

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.

15-50 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

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.

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.

Spikelets

2.4-3.2 mm long, 0.7-1.2 mm wide, ellipsoid to obovoid, often reddish throughout, short-pubescent.

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

Lower glumes

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.

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.

Basal

rosettes poorly differentiated;

sheaths glabrous;

blades 2-4 cm, narrow, similar to those of the lower cauline leaves, ascending to spreading.

rosettes well-differentiated;

blades 1.5-6 cm, ovate to lanceolate.

Primary

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 2-7 cm long, 2/3 to nearly as wide as long, with relatively few spikelets, exserted;

branches flexuous, spreading or reflexed, scabridulous to densely puberulent.

2n

= 18.

= 18.

Dichanthelium wilcoxianum

Dichanthelium portoricense

Distribution
from FNA
CO; IA; IL; IN; KS; MN; MT; ND; NE; NM; OK; SD; WI; WY; AB; MB; SK
[WildflowerSearch map]
[BONAP county map]
from USDA
[WildflowerSearch map]
[BONAP county map]
Discussion

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 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.)

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
Source FNA vol. 25, p. 449. FNA vol. 25, p. 441.
Parent taxa Poaceae > subfam. Panicoideae > tribe Paniceae > Dichanthelium > sect. Linearifolia Poaceae > subfam. Panicoideae > tribe Paniceae > Dichanthelium > sect. Lancearia
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. portoricense, D. ravenelii, D. scabriusculum, D. scoparium, D. sphaerocarpon, D. strigosum, D. tenue, D. wrightianum, D. ×anthophysum
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
Subordinate taxa
D. portoricense subsp. patulum, D. portoricense subsp. portoricense
Synonyms Panicum wilcoxianum Panicum portoricense
Name authority (Vasey) Freckmann (Desv. ex Ham.) B.E Hansen & Wunderlin
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