Tribes Aveneae (1-8) and Stipeae (9-12). Use the key to grass tribes on pages 3-4 in the Grasses of Montana to learn the distinguishing features of these grass tribes. For Aveneae, we have seen Agrostis stolonifera, Alopecurus arudinaceus, Avena fatua, Calamagrostis stricta, Koeleria macrantha, Phalaris arundinacea, and Phleum pratense. For Stipeae, we have seen Stipa viridula. Be sure to run all of your grass samples through the keys in the Grasses of Montana so that you can develop an association of a taxonomic group (tribe, genus, species) with its diagnostic traits or morphologies.

1. Avena sativa. An annual bunchgrass sometimes escaping cultivation, the combination of a hairless lemma, straight or no awns, and an inconspicuous callus distinguish this species from wild oats.

2. Helictotrichon hookeri. Spike oat. A perennial bunchgrass with stems usually less than 0.5 m tall, the inflorescence is a spicate panicle and the florets are similar to those of Avena except smaller, mostly in open grasslands across most of northern Montana and occasional to the south in dry mountain meadows.

3. Arrhenatherum elatius. A perennial bunchgrass usually about 1 m tall with an open panicle and spikelets bearing dimorphic florets where the lower usually bears a more robust awn than the upper floret.

4. Ventenata dubia. An annual bunchgrass usually less than 3 dm tall, the open panicle has stiff wiry branches that persist after the spikelets have fallen, the spikelets have distinctly ribbed glumes and two florets, the upper one is seed bearing and awned and disperses separately from the rest of the spikelet, the lower is staminate and unawned or short awned and remains with the glume. Disarticulation is both above and below the glumes.

5. Anthoxanthum hirtum (Hierochloe odorata). A loosely bunched to single-stemmed perennial with creeping rhizomes, from wet meadows usually in the mountains throughout western Montana, the three florets per spikelet include the two lower being hairy and staminate and the upper being glabrous and seed bearing.

6. Anthoxanthum odoratum. A perennial bunchgrass, the stems and leaves have a fragrant odor when fresh, the 1st glume is the much shorter than the 2nd, three florets per spikelet include the two lower being awned from the back of the lemma and staminate and the upper being glabrous and seed bearing.

7. Holcus lanatus. A perennial bunchgrass often rooting at nodes, inflorescence of spicate panicles opening somewhat at or after anthesis, disarticulation both above and below glumes, the two dimorphic florets per spikelet include the upper being staminate and bearing a hooked awn and the lower being seed bearing and awnless, usually of moist disturbed settings.

8. Beckmannia syzigachne. A bunched to single stemmed annual, stems erect and usually less than 1 m tall, the laterally compressed oval spikelets are sessile and stacked along panicle branches in a second fashion, common along streams, ditches, and lake banks, and also in wet meadows.

9. Stipa richardsonii. A perennial bunchgrass from the western half of Montana in forest openings or dry meadows in the mountains.

10. Stipa nelsonii. A perennial bunchgrass similar to Stipa viridula but bunches less robust and stems more, slender florets (less then 1 mm in diameter), leaves without a hairy collar, and inhabiting typically higher elevation in mountain settings.

11. Stipa comata. A perennial bunchgrass, spikelets with long glumes and the floret bearing a long awn, the ligule of the leaves from the basal bunch is often conspicuously long, 3 mm long or longer.

12. Oryzopsis hymenoides. A perennial bunchgrass of very dry settings, the inflorescence is an open panicle with dichotomous branching, the floret of each spikelet bears a short awn that is deciduous early in the season.

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