Description: This native perennial grass is 1½–3' tall, forming tight bunches of leafy culms that are usually erect to ascending. Each slender culm is terete, unbranched, glabrous, and light green to light tan. There are typically about 3-5 alternate leaves along the length of each culm. The flat leaf blades are up to ¼" (6 mm.) across and 5" long; they are light green to blue-green, ascending to widely spreading, and rough-textured, particularly along their margins and lower surfaces. Usually the leaf blades are not conspicuously hairy. The open leaf sheaths are fairly tight, light to medium green, and longitudinally veined; usually they are not conspicuously hairy. The ligules are membranous, while the nodes are swollen, light green, and glabrous.
Each culm terminates in a slender panicle
of spikelets about 3-8" long. Slender sides branches up to 2½" long
occur in whorls along the central axis of this panicle; these side branches are
appressed, ascending, or slightly spreading. The slender panicle is more or
less straight, or it can nod to one side. There is some variability in the
length of the spikelets, glumes, and lemmas. Typically, each spikelet is about
3.5 mm. long, consisting of 2 glumes, 2-3 lemmas, and the florets of the
latter. The smaller glume is 2 mm. long, linear in shape, and keeled; the
larger glume is 2.5 mm. long, oblanceolate to narrowly ovate in shape, and
convex along the length of its outer surface. The lemmas are about 3 mm. long,
narrowly elliptic to elliptic, and convex along the length of their outer
surfaces (rather than keeled). Both the glumes and lemmas are hairless to
slightly pubescent and they lack awns. The blooming period occurs during the
late spring. Shortly afterwards, the spikelets change color from light green to
light tan. Disarticulation of the spikelets is below the glumes. Each mature
spikelet produces 1-3 small grains. The root system is fibrous.
Cultivation: The preference is light shade to full
sun, moist to slightly dry conditions, and soil that is loamy or rocky. This
cool season grass develops quickly during the spring and becomes mature no
later than mid-summer.
Range &
Habitat: Slender Wedge Grass is occasional to locally common
throughout Illinois (see
Distribution
Map). Habitats include rocky woodlands, open upland woodlands, areas along
woodland paths, meadows in wooded areas, gravelly seeps in partially shaded
areas, and moist prairies. Unlike the similar Sphenopholis obtusata
(Prairie Wedge Grass), Slender Wedge Grass is more often found in wooded areas
than prairies.
Faunal Associations:
Very little is known about floral-faunal relationships for this small genus of
grasses. However, it is known that they are palatable to hoofed mammalian
herbivores (horses, cattle, etc.), particularly during the early stages of
growth. White-Tailed Deer seem to prefer other plants (particularly many forbs)
to Sphenopholis spp. (Wedge Grasses).
Photographic Location: An upland area of Busey Woods
in Urbana, Illinois.
Comments:
Slender Wedge Grass is fairly unusual for a woodland grass because it has a
strong bunching habitat that is more typical of a prairie grass. Otherwise, its
appearance is fairly ordinary. Another scientific name of Slender Wedge Grass
is Sphenopholis obtusata major; under this taxonomy, the typical
variety, Sphenopholis obtusata obtusata, is Prairie Wedge Grass. Slender
Wedge Grass differs from the latter primarily by the shape of its larger
glumes, which are more narrow and pointed. The larger glumes of Prairie Wedge
Grass are obovate and nearly truncate; this latter grass is more often found in
prairies than woodlands and its inflorescence tends to be more erect and
spike-like. Because the spikelets of Wedge Grasses disarticulate below the
glumes, this makes it easier to distinguish them from other similar
grasses.