keys to the vascular plants of east texas - Botanical Research ...

862 POACEAE/CENCHRUS
Buchloe dactyloides (Nutt.) Engelm., (finger-like), BUFFALO GRASS. Low perennial, 30 cm or less
tall, stoloniferous, forming sod, dioecious or occasionally monoecious; culm nodes mostly glabrous;
leaves usually with short, curly blades 1–2.5 mm wide; ligule a ciliate membrane ca. 0.5–
1 mm long; staminate inflorescences elevated above the leaves, with 1–4 spike-like branches 6–
14 mm long; staminate spikelets usually 6–12 per branch, sessile, pectinately arranged, 4–6 mm
long, 2-flowered; glumes unequal, 1(–2)-veined; lemmas 3-veined; pistillate inflorescences usually
hidden in leafy portion of plant, closely subtended by inflated leaf sheaths, the 2–3(–4)
branches bur-like, the axes indurate, each usually with 3–5(–7) one-flowered spikelets, falling
entire; upper glume indurate, yellowish, the apex 3-toothed; lemma 3-veined, 3-lobed. Grasslands;
throughout TX, but more common from the Blackland Prairie westward; sc Canada and
c U.S. from WI s to LA w to MT and NV, also GA and VA. Apr–Sep. [Bouteloua dactyloides (Nutt.)
J.T. Columbus] This species is dominant over large areas of the short grass prairie of the Great
Plains and is one of the most important grazing species of that area. It was used by settlers in
making sod houses and is currently increasing in use as a drought resistant and low maintenance
yard grass—because of its relatively low maximum height, little mowing is required. It has been
suggested (Davidse 1987a) that the bur-like pistillate inflorescences may be animal dispersed.
CENCHRUS L. SANDBUR, GRASSBUR, SANDSPUR,
BUR GRASS, HEDGEHOG GRASS, DEVIL’S-BUR, STICKERS, GOAT-HEADS
Annuals or perennials, largely glabrous; culms often geniculate; leaf sheaths compressed and
keeled; ligule a short ciliate membrane; inflorescence spike-like, with zigzag, triangular-flattened
axis; spikelets enclosed in bur-like involucres (1–several spikelets per involucre) with
usually fused spines (flattened bristles) and bristles or (in C. myosuroides) only bristles; disarticulation
at base of involucres; callus below involucre flared/swollen apically; spikelets of 2
florets, the lower floret sterile and with glume-like lemma, the upper floret fertile and with
hardened grain-like lemma; glumes unequal, the lower smaller than the upper.
AA genus of ca. 16 species (Stieber & Wipff 2003) of warm and dry regions of America, Africa,
and India, characterized by C4 photosynthesis. Other authorities, however, recognize more
species—20 (Crins 1991) to 30 (Mabberley 1997). The bur-like spiny involucres are painful and
injurious to both humans and other animals—they are frequently found on shoelaces, socks,
and other clothing and on many animal species. The burs, which fall easily and serve as dispersal
units, often become embedded between the toes of dogs, necessitating veterinary attention,
and in various animals the burs are known to penetrate the mouth and tongue, causing
serious problems (Ken Lawrence D.V.M., pers. comm.). They are particularly problematic in areas
where sheep are raised and can damage the wool (Steyermark 1963). Cenchrus is closely related
to Pennisetum; some species of the former closely resemble the latter morphologically
(Chrtek & Osbornová 1996; Wipff & Veldkamp 1999), and the two have sometimes been combined
(e.g., Correll & Johnston 1970). Recent molecular studies suggest Pennisetum is “probably
paraphyletic” without the inclusion of Cenchrus (Gómez-Martínez & Culham 2000). However,
“Cenchrus generally differs from Pennisetum in having retrorsely scabrous or strigose inner
bristles that are usually fused to well above their bases” (Stieber & Wipff 2003), and until more
information is available, we are following most recent authorities in maintaining Cenchrus as a
separate genus. Pennisetum ciliare has been treated as a Cenchrus by some authorities (e.g.,
Gould 1975b; Webster 1988; Crins 1991; Watson & Dallwitz 1992; Yatskievych 1999). However,
we are following other workers (e.g., Kartesz 1999; Hatch 2002; Wipff 2003j) in treating it in
Pennisetum. While it seems more appropriately placed in Pennisetum (e.g., spikelets subtended
only by an involucre of bristles, not spines; bristles antrorsely barbed; molecular evidence—
Giussani et al. 2001; cytological evidence—S. Hatch, pers. comm.), it does exhibit some fusion of
the involucre bristles (at least basally) as in species of Cenchrus, and it has the callus below the
involucre flared/swollen apically—a character which is uniformly present in Cenchrus, but not