Flora of North America species comparison

(3)10-50(80) cm, often highly branched above the base.

annual, erect, solid or hollow, usually unbranched.

cauline, glabrous;

sheaths shorter than the internodes, not disintegrating into threadlike fibers;

ligules 0.4-1 mm;

blades 2-14 cm long, 1-2.5 mm wide, flat to involute.

distichous;

sheaths usually open;

auricles absent;

abaxial ligules absent or of hairs;

adaxial ligules membranous and ciliate or of hairs;

blades without pseudopetioles;

mesophyll cells radiate or non-radiate;

adaxial palisade layer absent;

fusoid cells absent;

arm cells absent;

kranz anatomy absent or present, when present, with 1 or 2 parenchyma sheaths;

midribs simple;

adaxial bulliform cells present;

stomatal subsidiary cells dome-shaped or triangular;

bicellular microhairs present, with long, slender, thin-walled terminal cells.

panicles, 5-15(20) cm long, 0.5-3 cm wide, often interrupted below;

nodes glabrous or with straight, less than 0.5 mm hairs;

primary branches 1-4 cm, erect to ascending, without axillary pulvini, with 3-8 spikelets.

terminal, not leafy, usually panicles, sometimes spikes or racemes;

disarticulation above the glumes.

crowded.

bisexual, with 1 floret;

rachilla extension absent.

unequal, 1-veined, acuminate;

lower glumes 4-8 mm;

upper glumes 6-11 mm;

calluses 0.5-0.8 mm;

lemmas 6-9 mm, slightly keeled, midveins scabrous, junction with the awns not evident;

awns not disarticulating at maturity, flattened and straight to somewhat curved at the base, central rib flanked by equally wide pale wings;

central awns 7-15(20) mm;

lateral awns somewhat shorter, occasionally only 1-2 mm;

anthers 3, 0.3-0.7 mm.

2, usually longer than the florets, usually acute or acuminate;

florets terete or laterally compressed, with well-developed calluses;

lemmas 1- or 3-veined, more or less coriaceous, with a germination flap, lemma margins overlapping at maturity and concealing the paleas, apices evidently 3-awned;

awn bases often forming a column, lateral awns occasionally reduced or absent;

paleas less than 1/2 as long as the lemmas;

lodicules usually present, 2, free, membranous, glabrous, heavily vascularized;

anthers 1-3;

ovaries glabrous;

haustorial synergids absent;

styles 2, free to the base but close.

usually fusiform, falling with the lemma and palea attached;

hila short or long, linear;

endosperm hard, without lipid;

starch grains compound;

embryos small or large relative to the caryopses;

epiblasts absent;

scutellar cleft present or absent;

mesocotyl internode elongated;

embryonic leaf margins meeting, x = 11, 12.

= 22.