Piptochaetium avenaceum

(L.) Parodi
Common names: Blackseed speargrass
Endemic
Synonyms: Stipa avenacea
Treatment appears in FNA Volume 24.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Culms (30) 40-100 cm, glabrous; nodes 2-3, narrowed, yellowish to reddish. Sheaths glabrous; ligules rounded, sometimes highest at the sides, entire, of basal leaves 0.4-3.3 mm, of upper leaves 1.8-2.5 mm; blades 8-30 cm long, 0.6-3 mm wide, usually involute and about 0.5 mm in diameter, 3-veined, abaxial surfaces glabrous, smooth, adaxial surfaces scabrous over the veins, margins scabrous. Panicles 14-22 cm, open, with (10) 15-25 spikelets; branches lax, divergent, spikelets confined to the distal 1/2; pedicels 15-50 mm, flattened, hispid. Glumes subequal, 9-15 mm long, 0.9-1.9 mm wide, acute; lower glumes 3 (5) -veined; upper glumes 5-veined; florets 7-13 mm long, 1-1.2 mm thick, terete; calluses 2-3 mm, sharp, strigose, hairs golden brown at maturity; lemmas glabrous, tan to brown at maturity, smooth below, sharply tuberculate in the distal 1/3, constricted below the crown; crowns 0.5-0.6 mm wide, straight, not revolute, hairy, hairs 0.2-0.5 mm, golden brown; awns 40-75 mm, persistent, twice-geniculate, basal segment hispid, terminal segment scabrous; paleas 7-14 mm; anthers 0.3-0.5 mm or 3-4 mm, not penicillate. Caryopses 3.5-6 mm, terete. 2n = 22. Cialdella and Giussani (2002) mistakenly cited Gould (1958) as having reported 2n = 28.

Distribution

Del., D.C., W.Va., Fla., N.J., Conn., Mass., R.I., La., Tenn., N.C., S.C., Pa., N.Y., Va., Ont., Ala., Mo., Ark., Ga., Ind., Okla., Md., Tex., Ohio, Mich., Miss., Ky.

Discussion

Piptochaetium avenaceum grows in open oak and pine woods, often on sandy soils, throughout most of the coastal plain of the eastern United States, extending north up the Mississippi valley, and also on the east side of Lake Michigan. With the exception of one record from southern Ontario, Canada (collected in 1965 and not seen in Canada since, even though it has been searched for, fide Michael Oldham, pers. comm.), P. avenaceum is known only from the contiguous United States.

Piptochaetium avenaceum is very similar to P. avenacioides, differing only in its smaller size and more widespread distribution. It is also similar to P. leianthum (Hitchc.) Beetle, a species of northeastern Mexico, from which it differs in it larger size. The existence of two ranges of anther length suggests that the species is sometimes cleistogamous.

Selected References

None.

Lower Taxa

None.

No values specified."decumbent" is not a number.

... more about "Piptochaetium avenaceum"
membranous +  and scarious +
not penicillate +
prow-tipped +  and sulcate +
awned +  and bifid +
Mary E. Barkworth +
(L.) Parodi +
twisted +  and not branched +
1 (?) +  and 3 (?) +
subterminal +  and eccentric +
4 cm40 mm <br />0.04 m <br /> (7.5 cm75 mm <br />0.075 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
8 cm80 mm <br />0.08 m <br /> (30 cm300 mm <br />0.3 m <br />) +
not evident +
convolute +  and flat +
0.5 cm5 mm <br />0.005 m <br /> (?) +
0.06 cm0.6 mm <br />6.0e-4 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
spikelike +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
Blackseed speargrass +
branching +  and not branched +
perennial +  and annual +
intravaginal +  and basal +
40 cm400 mm <br />0.4 m <br /> (100 cm1,000 mm <br />1 m <br />) +
not woody +
Del. +, D.C. +, W.Va. +, Fla. +, N.J. +, Conn. +, Mass. +, R.I. +, La. +, Tenn. +, N.C. +, S.C. +, Pa. +, N.Y. +, Va. +, Ont. +, Ala. +, Mo. +, Ark. +, Ga. +, Ind. +, Okla. +, Md. +, Tex. +, Ohio +, Mich. +, Miss. +  and Ky. +
0 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
0.7 cm7 mm <br />0.007 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
sometimes longer +
3-7(8)-veined +
9mm +  and 15mm +
subtending +
subequal +
membranous +
0.9mm +  and 1.9mm +
golden brown +
uncinate +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
solid +  and hollow +
basally concentrated +  and evenly distributed +
0.18 cm1.8 mm <br />0.0018 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
tan +  and brown +
tuberculate +
narrowed +
constricted +
coriaceous +  and indurate +
truncate +  and acute +
membranous +
inconspicuous +
acute +  and blunt +
yellowish +  and reddish +
concealed +  and prominent +
2 +  and 3 +
narrowed +
2 +  and 1 +
well-developed +
reduced +
0.7 cm7 mm <br />0.007 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
14 cm140 mm <br />0.14 m <br /> (22 cm220 mm <br />0.22 m <br />) +
flattened +
1.5 cm15 mm <br />0.015 m <br /> (5 cm50 mm <br />0.05 m <br />) +
dry +  and fleshy +
not prolonged +
1/2 +, 15 +  and 25 +
unisexual +  and bisexual +
laterally compressed +  and terete +
0.4 cm4 mm <br />0.004 m <br /> (2.2 cm22 mm <br />0.022 m <br />) +
1 +  and 3 +
simple +  and compound +
2 (?) +  and 3 (?) +
Stipa avenacea +
Piptochaetium avenaceum +
Piptochaetium +
species +
membranous +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
prow-tipped +  and sulcate +
inconspicuous +
plant +  and cespitose +
aquatic +  and terrestrial +