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rattail smutgrass, smut grass

composite dropseed, rough dropseed, sporobole rude, tall dropseed

Habit Plants perennial; cespitose, with tough fibrous roots, not rhizomatous. Plants perennial; cespitose, sometimes rhizomatous.
Culms

30-100 (120) cm.

(20)30-130(150) cm.

Sheaths

usually keeled below, glabrous;

ligules 0.2-0.5 mm;

blades (6)10-30(50) cm long, 1-5 mm wide, flat, glabrous on both surfaces.

with sparsely hairy apices, hairs to 3 mm;

ligules 0.1-0.5 mm;

blades not conspicuously distichous, 5-70 cm long, 1.5-10 mm wide, flat, folded, or involute, abaxial surface glabrous or pilose, adaxial surface glabrous or scabridulous, margins glabrous.

Panicles

20-35(50) cm long, 0.3-2.2(3) cm wide, contracted, narrow, sometimes included in the uppermost sheath;

primary branches 0.4-2.5(5) cm, appressed or spreading to 40° from the rachis, as long or longer than the adjacent internodes;

secondary branches appressed, spikelet-bearing to near the base;

pulvini glabrous;

pedicels 0.1-1.8 mm, appressed.

terminal and axillary, 5-30 cm long, 0.4-1.6 cm wide, usually spikelike, partially included in the uppermost sheath, with 15-90 spikelets per cm2 (exposed portion, when pressed);

lower nodes with 1-2(3) branches;

primary branches 0.4-6 cm, appressed, spikelet-bearing to the base;

secondary branches appressed;

pulvini glabrous;

pedicels 0.3-3.5 mm, appressed, glabrous or scabridulous.

Spikelets

2-2.6(2.7) mm, plumbeous to light brownish.

4-6(10) mm, stramineous to purplish-tinged.

Glumes

subequal, ovate or obovate, membranous;

lower glumes 0.5-1 mm, often without midveins;

upper glumes 0.8-1.6 mm, 1/2 - 2/3 as long as the florets, acute to obtuse, entire;

lemmas 1.8-2.6(2.7) mm, ovate, membranous, glabrous, acute or obtuse;

paleas 1.9-2.4 mm, ovate, membranous, glabrous;

anthers 3, 0.5-1.1 mm, white, sometimes purple-tinged.

subequal, lanceolate, membranous to chartaceous, midveins usually greenish;

lower glumes (1.2)2-4 mm;

upper glumes (2)2.5-5(6) mm, slightly shorter or longer than the lemmas;

lemmas (2.2)3-6(10) mm, lanceolate, membranous to chartaceous and hyaline, glabrous, smooth, occasionally 2- or 3-veined, acute to obtuse;

paleas (2.2)3-6(10) mm, ovate to lanceolate, membranous;

anthers 0.2-3.2 mm, yellow to orangish.

Fruits

1-1.2 mm, quadrangular, laterally compressed, reddish-brown, truncate.

1-2 mm, ellipsoid, laterally flattened, often striate, reddish-brown;

pericarps gelatinous, slipping from the seeds when wet.

2n

= 18, 24, 36.

= 54, 88, 108.

Sporobolus indicus

Sporobolus compositus

Distribution
from FNA
AL; AR; CA; FL; GA; IL; KY; LA; MD; MI; MO; MS; NC; NJ; NY; OK; OR; PA; SC; TN; TX; VA; HI; PR; Virgin Islands
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; AZ; CO; CT; DE; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NJ; NM; NY; OH; OK; OR; PA; RI; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; BC; MB; NB; ON; QC
[WildflowerSearch map]
[BONAP county map]
Discussion

Sporobolus indicus is a pantropical species. It commonly grows in disturbed places and open areas such as roadsides, pastures, and lake shores. In the Flora region, it is found on sandy or clay soils and is associated with many plant communities. The spikelets and upper leaves are often covered with hyphomycetous fungi (Bipolaris spp.); hence the common name of "smutgrass".

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Sporobolus compositus grows along roadsides and railroad right of ways, on beaches, and in cedar glades, pine woods, live oak-pine forests, prairies, and other partially disturbed, semi-open sites at 0-1600 m. Its range lies entirely within the Flora region.

The Sporobolus compositus complex is a difficult assemblage of forms, perhaps affected by their primarily autogamous breeding system (Riggins 1977). Asexual proliferation via rhizomes adds to the species' ability to maintain local population structure and to perpetuate unique character combinations.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Rhizomes present
var. macer
1. Rhizomes absent.
→ 2
2. Culms slender, 1-2(2.5) mm thick; upper sheaths usually less than 2.5 mm wide; panicles with 16-36 spikelets per cm2 when pressed
var. drummondii
2. Culms stout, 2-5 mm thick; upper sheaths usually 2.6-6 mm wide; panicles with 30-90 spikelets per cm2 when pressed
var. compositus
Source FNA vol. 25, p. 122. FNA vol. 25, p. 121.
Parent taxa Poaceae > subfam. Chloridoideae > tribe Cynodonteae > Sporobolus Poaceae > subfam. Chloridoideae > tribe Cynodonteae > Sporobolus
Sibling taxa
S. airoides, S. buckleyi, S. clandestinus, S. coahuilensis, S. compositus, S. contractus, S. creber, S. cryptandrus, S. curtissii, S. diandrus, S. domingensis, S. fimbriatus, S. flexuosus, S. floridanus, S. giganteus, S. heterolepis, S. interruptus, S. jacquemontii, S. junceus, S. nealleyi, S. neglectus, S. pinetorum, S. purpurascens, S. pyramidatus, S. silveanus, S. tenuissimus, S. teretifolius, S. texanus, S. vaginiflorus, S. virginicus, S. wrightii
S. airoides, S. buckleyi, S. clandestinus, S. coahuilensis, S. contractus, S. creber, S. cryptandrus, S. curtissii, S. diandrus, S. domingensis, S. fimbriatus, S. flexuosus, S. floridanus, S. giganteus, S. heterolepis, S. indicus, S. interruptus, S. jacquemontii, S. junceus, S. nealleyi, S. neglectus, S. pinetorum, S. purpurascens, S. pyramidatus, S. silveanus, S. tenuissimus, S. teretifolius, S. texanus, S. vaginiflorus, S. virginicus, S. wrightii
Subordinate taxa
S. compositus var. compositus, S. compositus var. drummondii, S. compositus var. macer
Synonyms S. poiretii S. asper
Name authority (L.) R. Br. (Poir.) Merr.
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