Piptochaetium pringlei
Piptochaetium avenaceum
Pringle needlegrass, Pringle speargrass, Pringle's spear grass
black-seed spear grass, blackseed needlegrass
50-125 cm, mostly glabrous, pubescent below the nodes;
nodes 2-3, dark, 1 glabrous or slightly pubescent.
(30)40-100 cm, glabrous;
nodes 2-3, narrowed, yellowish to reddish.
smooth to scabridulous;
ligules of basal leaves 0.5-2.8 mm, truncate to rounded, of upper leaves 1-3.5 mm, rounded to acute;
blades 10-30 cm long, 1-3.5 mm wide, 3-5-veined, abaxial surfaces glabrous, smooth, adaxial surfaces smooth or scabrous over the veins, margins smooth or scabrous.
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.
6-20 cm, open, with 10-25 spikelets;
branches ascending, flexuous;
pedicels to 1 mm, flattened, hispid.
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.
subequal, 9-12 mm long, 2.5-3.5 mm wide;
lower glumes 5-7-veined;
upper glumes 7-veined;
florets 6.5-10 mm long, 1.5-2.1 mm thick, terete to somewhat laterally compressed;
calluses 0.6-1.9 mm, blunt to acute, strigose;
lemmas golden brown to dark brown at maturity, shiny or not, smooth to spiny-tuberculate distally or for almost their entire length, pubescent, hairs tawny to golden brown, evenly distributed or somewhat more abundant on the basal 1/2, apices tapering to the crown;
crowns 0.5-0.6 mm, inconspicuous, straight, hairy, hairs 0.5-1 mm;
awns 19-27(35) mm, persistent, twice-geniculate, sometimes inconspicuously so;
paleas 6.3-9.5 mm;
lodicules 2, 1-1.5 mm, acute;
anthers 3.5-5.5 mm, sometimes penicillate.
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.
about 7 mm, fusiform.
3.5-6 mm, terete.
& Giussani (2002) mistakenly cited Gould (1958) as having reported 2n = 28.
= 42.
= 22.
Piptochaetium pringlei
Piptochaetium avenaceum
Piptochaetium pringlei grows in oak woodlands, often on rocky soils, in the southwestern United States and northwestern Mexico. It is often confused with P. fimbriatum; it differs from that species in having longer florets and sharper calluses.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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