Sporobolus interruptus
Sporobolus texanus
black dropseed
Texas dropseed
25-60 cm.
20-70 cm, erect to decumbent, glabrous or scurfy roughened below.
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.
rounded basally, apices glabrous or with scattered, appressed, papillose-based hairs, hairs to 4 mm;
ligules 0.2-0.6 mm;
blades 2.5-13(18) cm long, 1-4.2 mm wide, flat to involute, glabrous abaxially, scabrous adaxially, margins scabridulous, often also with a few papillose-based hairs;
flag blades ascending.
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.
10-35 cm long, 4.5-30 cm wide, open, diffuse, subpyramidal, about as long as wide, partially included in the uppermost leaf sheath;
lower nodes with 1-2 branches;
primary branches 4-14 cm, capillary, spreading 10-80° from the rachis;
secondary branches spreading, without spikelets on the lower 1/3 - 1/2;
pedicels 6-25 mm, spreading.
4.5-6.6 mm, plumbeous.
2.3-3 mm, purplish-tinged.
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 to lanceolate, membranous;
lower glumes 0.5-1.7 mm, often without midveins;
upper glumes 1.7-3 mm, at least 2/3 as long as the florets, often longer;
lemmas 1.8-3 mm, lanceolate to ovate, membranous, glabrous, acute;
paleas 1.7-2.9 mm, ovate, membranous, glabrous, often splitting as the fruit matures;
anthers 0.3-1 mm, yellowish.
about 3 mm long, 1.5-1.7 mm thick, pyriform-globose;
embryo dark brown to blackish;
endosperm reddish-brown.
1.1-1.5 mm, obovoid, light brown, translucent, occasionally rugulose.
= 30.
= unknown.
Sporobolus interruptus
Sporobolus texanus
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 texanus grows along rivers, ponds, and in wet alkaline habitats, at 100-3300 m. It is known only from the United States.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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