Part 7 - UNC Herbarium

POACEAE 876
dichotomum (Linnaeus) Gould var. breve (Hitchcock & Chase) Gould & Clark – K, Z; = P. chamaelonche Trinius var. breve
(Hitchcock & Chase) Lelong – X]
Dichanthelium dichotomum (Linnaeus) Gould var. glabrifolium (Nash) Gould & Clark, Smooth-leaved Witch Grass,
endemic to peninsular FL, mostly near the west coast. Like D. chamaelonche ssp. breve, this taxon appears to be more closely
related to D. chamaelonche than to D. dichotomum or D. ensifolium. [= K, Z; = Panicum glabrifolium Nash – HC, S; < P.
chamaelonche Trinius var. chamaelonche – X]
Dichanthelium leibergii (Vasey) Freckmann, Leiberg's Witch Grass, NY and PA west to Alberta, ND, and KS. [= FNA, K,
Z; = Panicum leibergii (Vasey) Scribner – C, F, G, HC]
Dichanthelium malacophyllum (Nash) Gould, Soft-leaf Witch Grass, KY and TN west to KS and TX. Primarily a plant of
cedar glades and dry calcareous soils. Reported from SC by FNA, but source of record has not been identified. [= FNA, K, Z; =
Panicum malacophyllum – F, G, HC, S]
Dichanthelium nudicaule (Vasey) B.F. Hansen & Wunderlin, ranges from the FL Panhandle and s. AL west to MS. [= Q; =
Panicum nudicaule Vasey]
Dichanthelium wilcoxianum (Vasey) Freckmann is shown as occurring in SC and MS on the range map in FNA, but the
source of these records is not known for this plant primarily of dry prairies in the Upper Midwest. It is not treated here.
Dichanthelium xanthophysum (A. Gray) Freckmann, Slender Witch Grass, ME south to PA, west to SD; Nova Scotia to
Saskatchewan. [= FNA, K, Z; = Panicum xanthophysum A. Gray – C, F, G, HC]
Panicum chrysopsidifolium Nash is treated variously by the cited sources. According to Z, who examined an isotype
collection and found the ligule to be 2.5 mm long, it belongs to D. acuminatum var. acuminatum. Plants referred to by HC all
have ligules < 1 mm long, and apparently belong to the D. aciculare complex. These plants are described as having densely
villous nodes, internodes, sheaths, and blades; the blades 5-10 cm long and 3-5 mm wide; and spikelets 1.9-2.2 mm long,
obovate, and villous. HC gives a range of se. VA to FL, west to TX, along the Coastal Plain in sandy oak or pine woods. This
entity needs further scrutiny.
Panicum glutinoscabrum Fernald is an entity known only locally from "boggy spots" in southeastern Virginia. It is treated
as a full species by F, but is placed in synonymy with Dichanthelium scoparium (Lamarck) Gould by FNA; with D. acuminatum
(Swartz) Gould & Clark var. acuminatum by Z; with P. lanuginosum Elliott var. fasciculatum (Torrey) Fernald by C; and with P.
huachucae Ashe var. fasciculatum (Torrey) Hubb. by HC. Panicum glutinoscabrum is described as having culms 7-9 dm high;
elongate internodes with cinereous puberulence and black, warty, viscid glands; villous nodes; glutinous-warty and scabrous
sheaths and blades; ligule 4-5 mm long; minutely puberulent panicle axis; spikelets ellipsoid, subacute, 1.7-1.8 mm long,
pubescent; first glume subacute, 0.6-0.7 mm long. Y concedes that "I am not able to render a decision on the poorly known P.
glutinoscabrum Fernald, but I suggest that it is a hybrid between a member of the D. acuminatum complex and D. scoparium
(Lam.) Gould - the latter contributing the genes for height and viscid sheaths."
Panicum malacon Nash, here placed in synonymy with Dichanthelium ovale var. ovale, needs additional study. It is
distinguished by HC and S as having spikelets 3-3.2 mm long with a first glume situated conspicuously below the second glume
and sterile lemma, half or more as long as the spikelet; and leaves 3-5 mm wide, puberulent beneath, and puberulent to glabrous
above. The leaf width and puberulence characters are not consistent with descriptions of D. ovale, and the placement of P.
malacon within D. ovale by current treatments (including this one) may be in error. The description of P. malacon in RAB
differs greatly from that of HC and S, and falls well outside the range of D. ovale characters. In RAB, P. malacon is described as
having spikelets 3.5-4 mm long, and leaves 5-14 mm wide. This description may be based on specimens from the Sandhills of
SC at NCU identified as P. malacon and matching the RAB description. These specimens appear to be misidentified collections
of D. oligosanthes var. oligosanthes.
Digitaria Haller (Crab Grass)
A genus of about 200 species, primarily in the tropics and subtropics. Most of our species occur primarily in disturbed situations;
their original distributions and habitats are now obscure. References: Wipff in FNA (2003a); Webster (1987)=Z; Wipff & Hatch
(1994)=Y; Wipff (1996b)=X; Webster (1980).
1 Inflorescence an open panicle; spikelets long-pedicellate, borne singly at the ends of long panicle branches; [section
Pennatae] ............................................................................................................................................ D. cognata var. cognata
1 Inflorescence of 2-several spikelike racemes borne digitately or in close proximity near the summit of the culm; spikelets
sessile or short-pedicellate, borne more-or-less closely spaced along the racemes.
2 Rachis of each raceme narrow, trigonous, only slightly (if at all) winged.
3 Spikelets 1.7-2.2 mm long; plants 3-10 dm tall; racemes to 10 cm long; upper sheaths glabrous, lower sheaths
glabrous to sparsely pilose ............................................................................................... D. filiformis var. filiformis
3 Spikelets 2.0-2.8 mm long; plants 8-15 dm tall; racemes to 25 cm long; upper sheaths glabrous or pilose, lower
sheaths densely pilose ..................................................................................................................................D. villosa
2 Rachis of each raceme broad (0.5-1 mm wide), winged, the wings as wide as or wider than the rachis proper.
4 Lower sheaths glabrous; second glume 0.75-1× as long as the first glume; fertile lemma dark brown or black at
maturity.
5 Hairs of the spikelet not minutely capitate; second glume ca. 0.75 as long as the first glume; spikelets
averaging 1.5 mm long...................................................................................................................D. violascens