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1 Spikelets disarticulating below the glumes, the spikelets falling as a whole or in clusters; [tribe Poeae] |
1 Spikelets disarticulating above the glumes, the glumes remaining attached to the pedicel. |
..2 Spikelets dimorphic, paired, each pair consisting of a lower spikelet with sterile florets and an upper spikelet one with fertile florets; [tribe Poeae] |
..2 Spikelets monomorphic. |
....3 Spikelets each with 1 fertile (bisexual) floret, with 1-several sterile florets, either towards the base or towards the tip of the spikelet. |
......4 Fertile floret basal, with 1-several sterile florets towards the tip of the spikelet; [tribe Cynodonteae; subtribe “ incertae sedis”] |
......4 Fertile floret terminal, with 1-several sterile florets towards the base of the spikelet (the sterile florets sometimes knoblike or like tufts of hairs, and not obviously like florets); [tribe Poeae]. |
........5 Spikelets with 2 florets, the lower floret staminate and of similar size as the upper, pistillate or bisexual floret; lemma of the lower floret awned; lemma of the upper floret unawned or awned |
........5 Spikelets with 2-3 florets, the lower 1-2 florets staminate or sterile, either highly reduced to knobs or tufts of hairs, or shorter than to longer than the terminal, bisexual floret; lemma of the lower florets either awned or unawned; lemma of the upper floret unawned. |
..........6 Lower sterile florets 2, shorter than to exceeding the bisexual floret; fresh leaves with sweet vanilla odor when crushed; lemma of the lower florets awned or unawned |
............ 7 Glumes unequal, the lower shorter than the upper; lowest 2 florets sterile. |
............ 7 Glumes subequal; lowest 2 florets staminate. |
..........6 Lower sterile florets 1-2, either highly reduced to knobs or tufts of hairs, or consisting of linear to lanceolate lemmas up to ¾ as long as the bisexual floret; all lemmas unawned |
....3 Spikelets each with 2 or more fertile florets. |
............ ..8 Spikelets 18-50 mm long; glumes 9-11-veined; [tribe Poeae] |
............ ..8 Spikelets 2.5-20 mm long; glumes 1-7-veined. |
............ ....9 Lemma awns apical or dorsal (arising from the apex or back of the lemma or sometimes the midvein prolonged into a 1 mm awn). |
............ ......10 Spikelets 7-20 mm long, with 3-12 florets; ligule of hairs; lemma awn 5-15 mm long; [collectively widespread in our area]; [tribe Danthoniae] |
............ ......10 Spikelets 2.5-7.5 mm long, with 2-3(-4) florets; ligule membranous, sometimes ciliolate but not only consisting of hairs, 0.5-4 mm long; lemma awn 1-9 mm long; [tribe Poeae] |
............ ........11 Awns of the lemmas 1 mm long, essentially a minute prolonged extension of the lemma midvein; lemma apices acute |
............ ........11 Awns of the lemmas 2-8 mm long (therefore conspicuous and not merely a minute midvein extension), bent or geniculate and often basally-twisted and exceeding lemma apices; lemma apices bifid or bicuspidate. |
............ ..........12 Panicle branches densely pubescent, usually glistening yellowish-brown or yellowish to tan; panicles either 1-5 cm ( Trisetum aureum) OR 5-20 cm long ( Trisetum flavescens); leaves evenly distributed; ligules 0.5-1(2) mm, obtuse, lacerate, sometimes ciliolate; plants sometimes with rhizomes to 7 cm long ( T. flavescens); [occurring very sporadically in disturbed sites throughout our area or as a ballast waif in NJ] |
............ ..........12 Panicles branches glabrous or sparsely pubescent, usually silvery-shiny; panicles (5)20-30(50) cm long; leaves mostly basal or evenly distributed; ligules 0.5-4 mm, truncate or rounded; plants not rhizomatous; [a native of cool, moist, undisturbed northern sites; rare and disjunct in high elevation areas s. to VA] |
............ ....9 Lemma awns basal (arising from the lower half of the lemma); [tribe Poeae]. |
............ ............ 13 Awns geniculate and articulated near the middle joint with a ring of minute conical protuberances, the distal segment of the lemma clavate and differing in shape from the proximal lemma segment; [NJ and PA northward] |
............ ............ 13 Awns straight or geniculate (sometimes only slightly so), if geniculate then the awn not bearing a distinct ring at the joint and not bearing a clavate distal segment; [collectively widespread]. |
............ ............ ..14 Rachilla glabrous, not prolonged beyond the upper floret; spikelets 1.7-3.8 mm long |
............ ............ ..14 Rachilla hairy, prolonged beyond the upper floret as a bristle; spikelets 2.5-7 mm long |
............ ............ ....15 Lemma awn 4-8 mm long, geniculate, exserted beyond the tips of the glumes; lemmas minutely scabrous, dull; leaf blades involute, appearing filiform (rounded in cross-section); ligule 0.5-3 (-5) mm long |
............ ............ ....15 Lemma awn 2-3 mm long, straight or nearly so, scarcely (or not at all) exserted beyond the tips of the glumes; lemmas smooth, shiny; leaf blades flat or folded at the midvein (V-shaped in cross-section); ligule 3-10 (-17) mm long |