Sporobolus interruptus
Sporobolus teretifolius
black dropseed
wireleaf dropseed
25-60 cm.
(20)35-80(100) cm, wiry.
dull and fibrous basally, with scattered, contorted hairs to 5 mm, margins glabrous;
ligules 0.2-0.7 mm;
blades (5)8-20 cm long, 1-2.5 mm wide, flat to folded, glabrous or scattered-pilose on both surfaces, margins glabrous.
shiny and indurate basally, glabrous or appressed hairy elsewhere, hairs to 4 mm;
ligules 0.2-0.4 mm;
blades (10)25-54 cm long, 0.5-1.2 mm wide, terete or subterete at least basally, sometimes channeled for portions of their length, green to yellowish-green, senescing or turning tan in late fall, glabrous on both surfaces or the adaxial surface sparsely hairy basally, margins smooth.
5-20 cm long, (0.6)1-8 cm wide, longer than wide, narrowly pyramidal, open to somewhat contracted, not diffuse, well-exerted from the upper leaf sheath;
lower nodes with 1-2(3) branches;
primary branches 0.6-7 cm, appressed or spreading to 70° from the rachis, not capillary, without spikelets on the lower 1/3;
pedicels 0.8-5.5 mm, appressed to spreading.
10-26 cm long, 1-9 cm wide, open (contracted when immature), not diffuse, narrowly pyramidal to ovate;
lower nodes with 1-2(3) branches;
primary branches 1-8 cm, ascending or spreading to 40° from the rachis, not capillary, without spikelets on the lower 1/3;
secondary branches spreading;
pulvini hairy;
pedicels 3-18 mm, longer than the spikelets, spreading, with scattered ascending hairs.
4.5-6.6 mm, plumbeous.
4-5.6 mm, purplish-brown.
unequal, lanceolate, membranous;
lower glumes (2)2.5-4.2 mm;
upper glumes 3.8-6.5 mm, at least 2/3 as long as the florets;
lemmas 5-6.5 mm, ovate, membranous, glabrous, acute;
paleas 4.8-6.5 mm, ovate, membranous;
anthers 3-4.2 mm, yellow to purplish.
unequal, linear-lanceolate, membranous;
lower glumes 2-3.8 mm, 0.5-0.8 times as long as the upper glumes;
upper glumes 4-5.6 mm, usually longer than the florets;
lemmas 3.4-4.4 mm, ovate, membranous, glabrous, acute;
paleas 3.3-4.4 mm, ovate, membranous, glabrous;
anthers 1.5-2.6 mm, purplish.
about 3 mm long, 1.5-1.7 mm thick, pyriform-globose;
embryo dark brown to blackish;
endosperm reddish-brown.
not seen.
= 30.
= unknown.
Sporobolus interruptus
Sporobolus teretifolius
Sporobolus interruptus grows on rocky slopes and in dry meadows of open yellow pine and oak-pine forests and pinyon-juniper woodlands, at elevations from 1500—2300 m. It is an Arizonan endemic that is morphologically similar to S. heterolepis, but the two species are separated geographically, the range of the latter lying to the north and east of Arizona. The only reliable morphological difference between them is anther length (3-4.2 mm long in S. interruptus, 1.7-3 mm long in S. heterolepis). Cytologically, S. interruptus appears to be triploid, while 5. heterolepis appears to be an octoploid (2n = 72).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Sporobolus teretifolius is restricted to the southeastern United States, where it grows in wet to moist flatwoods and savannahs, at elevations of 10-150 m.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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