Subfamily Eragrostoideae: tribe Chlorideae. In North America, the diversity of this tribe is centered in desert regions of Mexico and adjacent USA. Montana harbors a limited number of Chloridae, so some of the very common North American Chloridae given below do not occur in the State. Regardless, be able to sight identify them to tribe. Use the key to grass tribes on pages 3-4 in the Grasses of Montana to learn the distinguishing features of this grass tribe. Be sure to run the Montana grass samples through the keys so that you can develop an association of a taxonomic group (tribe, genus, species) with its diagnostic traits or morphologies.

1. Spartina pectinata. A strongly rhizomatous perennial with stout stems, inflorescences of one-sided secund erect spikes that are usually closely appressed to the main inflorescence rachis, awns of the large second glume of each spikelets are conspicuous even when congested on the spike, common to saline seeps at lower elevation throughout Montana.

2 Spartina gracilis. A strongly rhizomatous perennial with stout stems, similar to the above but usually less than 1 m tall and the second glumes are shorter and lack long awns, common to saline seeps at lower elevations.

3. Schedonnardus paniculatus. A short-lived perennial bunchgrass with decumbent to occasionally erect stems, the dispersal unit is the inflorescence that bears long curved one-sided spikes each of which are laterally arranged along the main inflorescence rachis, the very narrow and slender one-sided spikes bear spikelets that are closely appressed to the inflorescence rachis, common to moderately disturbed sites such as along railroad tracks and in and around prairie dog towns. The inflorescence is the unit of dispersal.

4. Cynodon dactylon. A stoloniferous and rhizomatous perennial, often mat-forming and thus commonly used as a turf grass in warm temperate regions of the USA, superficially similar to crabgrass (Digitaria of tribe Paniceae) but the spikelets are laterally compressed, including the strongly keeled glumes.

5. Bouteloua gracilis. A perennial bunchgrass that forms patches of sod in wyoming sagebrush steppe, the secund spikes are laterally arranged along the main rachis, spikelets bear two florets, the upper of which is infertile.

6. Bouteloua eripoda. Black grama Not known from Montana, A stolon-producing perennial with densely whitish hairy lower stems (hence, eripoda), a range grass important to the deserts of southwestern USA and northern Mexico.

7. Bouteloua barbata. Bunched annuals with ascending to erect stems, the only annual grama to occur in Montana, and then on open ground and rocky hills, from Beaverhead, Carbon, and Gallatin Counties and probably not persisting.

8. Bouteloua curtipendula. A perennial bunchgrass with scaly rhizomes, each inflorescences with 20-50 secund lateral reflexed spikes, each mostly less than 1.5 cm long and containing 3-6 spikelets, the lateral spike is the unit of dispersal, mostly from open shrub steppe vegetation along the southern tier of Montana counties.

9. Buchloe dactyloides. Sod-forming perennial with creeping stolons, plants dioecious, staminate inflorescences of 1-3 secund lateral spikes, pistillate inflorescences with about 4 spikelets clustered into a short burr-like head enclosed in leaf sheaths, the burr-like cluster is the unit of seed dispersal, the leaf sheaths and blades are characteristically hirsute, mostly from southern Montana in disturbed dry open steppe communities.

10. Hilaria rigida. Not known from Montana, somewhat woody perennial bunchgrass with short woody rhizomes, inflorescence superficially approaches a 2-sided terminal spike but is actually a panicle of laterally arranged secund spikes that individually disarticulate from the main rachis, each disarticulating lateral spike comprises three spikelets, the terminal central one has 1 perfect (fertile) floret, and the two lateral spikelets have 1-2 staminate florets, the dense woolly hairs on the sheaths and nodes are characteristic of this genus, the ligule is actually a distinct basal membrane with well developed fringing ciliate hairs, but it is often obscured by the surrounding woolly hairs, common in desert and woodland grasslands of the southwestern USA and northern Mexico.

11. Eleusine indica. An annual bunchgrass with erect stems, inflorescence of 4-10 (17) secund spikes, most of them digitately arranged, spikelets with 5-7 florets, common to disturbed sites and lawns in warmer regions of the world and in North America, rare in Montana.

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