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

1068 POACEAE/SPHENOPHOLIS
mm wide from keel to margin (as folded), wider than in other species; lemma of second floret
strongly scabrous. Dense forests, forest openings; ne part of the Pineywoods; also reported from
the Edwards Plateau (Erdman 1965); se Canada (Ont.) and e U.S. from VT s to FL w to MI, MO,
and TX. Mar–May. This species is similar to S. obtusata but differs as in the key above and in
having longer anthers (1.2–2 mm long versus 0.3–0.8 mm long in S. obtusata) (Yatskievych 1999).
Sphenopholis obtusata (Michx.) Scribn., (obtuse, blunt), PRAIRIE WEDGESCALE, WEDGE GRASS.
Annual (in TX) 15–100(–120) cm tall; culms single or tufted; ligule 1–3 mm long, glabrous or
ciliate; leaf blades to 15(–20) cm long, 2–8 mm wide; inflorescence dense and spike-like or open,
the axis glabrous or minutely scabrous; spikelets 1.5–5 mm long, awnless; apex of upper glume
conspicuously obovate; lemmas glabrous to scaberulous. Widespread in TX; the map in Turner
et al. (2003) and the one presented here do not separate the varieties found in TX.
1. Inflorescences open (relatively), at least the lowest branches loosely ascending to spreading;
upper glume (larger of the 2 glumes) 3–6 times longer than wide (when viewed from the side—
width from keel to margin—not unfolded), apically blunt to acute ___________________________ var. major
1. Inflorescence dense, spike-like, almost all the branches appressed to ascending; upper glume 2–
3 times longer than wide (when viewed from the side—from keel to margin—not unfolded),
apically rounded ________________________________________________________________ var. obtusata
var. major (Torr.) Erdman, (greater, larger), SLENDER WEDGESCALE. Inflorescence relatively open.
Prairies, woodlands, moist bottomland forests, typically in more shaded sites than var. obtusata;
Angelina, Upshur (BRIT), Brazos, Grimes, Harris, Liberty, Polk, Smith (TAES), and Anderson
(Erdman 1965) cos.; also Gulf Prairies and Marshes and Edwards Plateau (Gould 1975b; Hatch
2002); this variety is much less common in East TX than var. obtusata; AR, LA, and TX. Apr–
May. [S. intermedia (Rydb.) Rydb., S. intermedia var. pilosa Dore, S. longiflora (Vasey) Hitchc.]
This taxon has sometimes been treated as a distinct species, S. intermedia (SLENDER
WEDGESCALE) (e.g., Hitchcock 1935, 1951; Allen 1992; Kartesz 1999). However, Erdman’s (1965)
detailed study documented numerous intermediates between this and S. obtusata var. obtusata.
Such intermediates are “scattered throughout the United States but are most plentiful in the
Southeast” (Tucker 1996). Some authors (e.g., Hitchcock 1935, 1951; Allen 1992; Kartesz 1999;
Daniel ined.) have also recognized forms of var. major with large spikelets as S. longiflora (TEXAS
WEDGESCALE), but according to Erdman (1965), “Although ‘S. longiflora’ of Texas has the largest
spikelets, there are numerous large-spikelet forms of S. obtusata var. major in all parts of its
range which intergrade completely with ‘S. longiflora.’ … Obviously ‘S. longiflora’ cannot be
separated on the basis of size from S. obtusata var. major and I am considering it as an extreme
form of that variety.” We are therefore following Erdman (1965), Tucker (1996), Yatskievych
(1999), and Hatch (2002) in treating these plants as S. obtusata var. major. According to Daniel
(ined.), this taxon “is frequently confused with Koeleria macrantha, but K. macrantha has a
dense, spike-like panicle, spikelets that disarticulate above the glumes, and glumes subequal
but similar in shape, with the lower glumes not less than the width of the upper glumes.”
var. obtusata, PRAIRIE WEDGESCALE, WEDGE GRASS. Inflorescence dense, spike-like; similar in aspect
to Koeleria macrantha but with upper glume much more obovate and more blunt at apex.
Prairies, low, open or partly shaded ground, clayey or sandy soils, typically in more open sites
than var. major; throughout most of TX; s Canada and throughout the U.S. Apr–Jun. [Aira
obtusata Michx.]
Sphenopholis pensylvanica (L.) Hitchc., (of Pennsylvania, but note different spelling), SWAMP
WEDGESCALE, SWAMP-OATS, the only other species of this small genus, occurs in the e U.S. as far
w as LA; it is not known from TX. This species can be distinguished by its large spikelets (ca. 5–
9.5 mm long) and lemmas with geniculate awns nearly as long as the lemma bodies. It has been
shown to hybridize with S. obtusata (Terrell 1963; Erdman 1965). [Trisetum pensylvanicum (L.) P.
Beauv. ex Roem. & Schult.]