| |
| | 2. Spikelets 1–4 per inflorescence branch; branch axis prolonged beyond terminal spikelet node 5+ mm; inflorescence branches deciduous in fruit, spikelets falling with branch |
| B. aristidoides var. aristidoides |
| | 2' Spikelets generally > 7 per inflorescence branch; branch axis terminated by spikelet; inflorescence branches persistent, spikelet axis breaking between glumes and lower floret |
| |
| | 3. Tip of lower floret lemma 2-lobed, central awn from sinus; base of awned upper floret hairy-tufted |
| B. barbata var. barbata |
| | 3' Tip of lower floret lemma tapered to central awn; base of upper floret glabrous |
| 2 B. trifida |
| | 1' Perennial, rhizomes or stolons sometimes present |
| |
| | 4. Inflorescence branches 13–60, deciduous in fruit, spikelets falling with branch |
| B. curtipendula |
| | 4' Inflorescence branches < 9, persistent in fruit, spikelet axis breaking between glumes and lower floret |
| |
| | 5. Lower stem internodes hairy; inflorescence branch axis slightly prolonged beyond terminal spikelet node |
| B. eriopoda |
| | 5' Lower stem internodes glabrous or minutely scabrous; inflorescence branch axis terminated by fertile or vestigial spikelet |
| |
| | 6. Base of awned upper floret hairy-tufted; tip of lower floret lemma 2-lobed, central awn from sinus |
| B. gracilis |
| | 6' Base of upper floret glabrous; tip of lower floret lemma tapered to central awn |
| 2 B. trifida
|