Part 7 - UNC Herbarium

POACEAE 846
...................................................................................................................................................A. curtissii
7 First glume as long as or nearly as long as the second glume; lemma 3-8 mm long, sparsely appressedpubescent................................................................................................................................A.
dichotoma
4 Lateral awns > 8 mm long; plant an annual or perennial.
8 Sheaths lanose or floccose (the hairs kinked and intertwined); nodes of the panicle axis with tufts of lanose or
floccose hairs........................................................................................................................................A. lanosa
8 Sheaths glabrous to pilose (the hairs straight and usually appressed, not intertwined); nodes of the panicle
axis glabrous or pilose.
9 Awn column (the connivent awns twisted together) or lemma beak (slender, narrowed, and twisted
portion of lemma body below the awns) 7-30 mm long; lemma body (including the beak, if present)
separated from the awns (or awn column) by an articulation zone, the awns (or awn column)
disarticulating at maturity from the lemma.
10 Panicle spiciform, broadest near the middle, dense, the spikelets overlapping strongly; awns (10-)
20-30 mm long, borne at the summit of a twisted lemma beak 7-30 mm long; culms simple or with
very few branches; plants perennial ..............................................................................A. spiciformis
10 Panicle almost corymbiform, broadest above the middle, open, the spikelets overlapping only
slightly; awns 30-40 mm long, not including the 8-15 mm long column formed by the twisting
together of the 3 awn bases; culms often much-branched; plants annual .....................A. tuberculosa
9 Awn column or lemma beak absent or < 7 mm long; lemma body not separated from the awns by an
articulation zone.
11 Spikelets borne singly at each node of the main axis, the inflorescence thus a spike or raceme .........
..............................................................................................................................................A. mohrii
11 Spikelets 2 or more per node of the main axis at most nodes (a few nodes may have single
spikelets), often with side branches present as well, the inflorescence thus a panicle or raceme.
12 First glume 1/3 to 3/4 as long as the second glume; awns 40-100 mm long................................
...........................................................................................................A. purpurea var. longiseta
12 First glume > 3/4 as long as the second glume; awns 8-40 mm long.
13 Annual .................................................................................. A. longespica var. geniculata
13 Perennial.
14 Central awn 15-40 mm long; first glume prominently 2-keeled, (8-) 9-14 mm long
when mature ..............................................................................................A. palustris
14 Central awn 8-25 mm long; first glume either 1-keeled and 6-14 mm long, or
weakly 2-keeled and 5.5-9 (-10) mm long when mature.
15 Central awn about 2× as thick as the lateral awns, divergent to reflexed; first
glume 1-keeled or weakly 2-keeled; [plants of moist to wet habitats].
16 Basal internode of the culm 0.3-0.6 mm wide; most nodes of the
inflorescence with 1-2 spikelets; all awns spreading, the central spirally
twisted basally and often contorted by as much as 180 degrees (best seen
in fresh material); central awn 15-20 mm long, lateral awns 11-16 mm
long, the ratio of the lateral:central awn length 0.69-0.80; lemma callus
beard 0.6-1.0 mm long........................................................ A. simpliciflora
16 Basal internode of the culm 0.7-1.2 mm wide; most nodes of the
inflorescence with 3 or more spikelets; central awn spreading to slightly
deflexed, not spirally twisted basally, the lateral awns ascending to erect
(best seen in fresh material); central awn 13-22 mm long, lateral awns 8-
15 mm long, the ratio of the lateral:central awn length 0.55-0.69; lemma
callus beard 0.2-0.6 mm long....................................................... A. virgata
15 Central awn < 1.5× as thick as the lateral awns, erect to divergent; first glume
1-keeled (rarely weakly 2-keeled); [plants of dry habitats].
17 Culms mostly > 10 dm tall and 3-6 mm in diameter near the base; awns 8-
15 mm long; panicle branches > 4 cm long; callus ca. 1.0 mm long............
.............................................................................................. A. condensata
17 Culms 5-8 (-10) dm tall and 1-4 mm in diameter near the base; awns 12-25
mm long; panicle branches 1-4 cm long; callus 0.4-0.8 mm long.
18 First glume 1-4 mm longer than the second glume (rarely about equal
to it); awns 15-25 mm long, straight or slightly contorted at the base;
leaf blades 1-3 mm wide, usually curling...................A. purpurascens
18 First glume shorter than or about equal to the second glume; awns 12-
18 mm long, spirally contorted at the base; leaf blades about 1 mm
wide, usually not curling................................................. A. tenuispica
Aristida beyrichiana Trinius & Ruprecht, Southern Wiregrass. Cp (GA, SC): sandhills, savannas, from very dry to
seasonally saturated soils; common. September-November. S. SC south to s. FL, west to s. MS. See Peet (1993) for discussion
of the taxonomy and ecology of this species; also see comments under A. stricta, which also apply here. Ward (2001) proposes