A SYNOPSIS OF THE GENUS SITANION. 



CHARACTERS OF THE GENUS. 



SITANION Rafine8(iiie, in .Tonni. Phy.s., 89: 103, 1819. 



J'UjUops Nutt., Gen. N. Am. PI., 1: 86, 1818; not Linn. (1737.) 

 Polyantherix Xees, iu Ann. Nat. Hist., Sev. I, 1: 284, 1838. 



Ciespitose perennials with intravaginal innovations. Rbacliis of tlie spike artic- 

 ulating at the nodes; spikelets rarely 1, usually 2, or sometimes 3 at each node, 

 each subtended by 2 persistent empty glumes. Empty glumes all subulate, 

 setaceous and entire; or lanceolate and bitid; or many-parted from near the 

 base; with recurving or spreading, scabrous awns terminating each lobe. 

 Flowering glumes all alike, lanceolate, acute,* or that of the lowest floret sterile 

 and resembling the subulate-setaceous long-awned empty glumes; entire or 

 with a single terminal recurving or spreading awn, or tritid and 3-awned. 

 Inllorescence a spike, or very rarely spiciform-paniculate. A "enus endemic to 

 western North America, containing 23 species. 



NoTK : Sitanion, section KhjmoUhx, consists of 4 species intermediate between this 

 genus and Elymiis. They are placed here tentatively, as being more closely allied 

 to Sitanion. 



AXALYTKAL KKY TO THK SI'F.CIKS. 



* Empty glumes many-lobed; lowest floret sterile, subulate-setaceous. 



t Culms robust, 6-9 dm. high, spike and florets large; awn of the flowering 



glume 8-10 cm. long 1. S. Jiiluitiim, 



ft Culms l-o dm. high; spike and florets medium or small; awn of the flower- 

 ing glume 2-7 cm. long, 

 t Leaves short, flat, divergent; the blades and sheaths villous. 



2. -S. villosum 

 U Leaves long, erect or ascending, involute, strigose or pubescent. 



= Awns of the empty and flowering glumes about as long as the axis 



of the spike 3. S. mnltiseium. 



= == Awns of the empty and flowering glumes shorter than the axis 

 of the spike. 

 « Leaves of the innovations involute, filiform, pilose. 



4. S. iwlyantherir. 

 h l.,eave8 of the innovations involute, rather rigid, strigose. 



5. <S. hreiiariitaium. 

 **Some of the empty glumes 2-nerved, bifid from about the middle, the lobes 

 abruptly divergent; lowest floret of one or both spikelets sterile and like the 

 empty glumes, but inserted on tlie rhachilla and falling away with it. 



tOnly one spikelet at each joint with fertile florets 6. .*^. minus. 



tt Both spikelets Ijearing fertile florets. 



i Sheaths and dorsal surface of leaves glabrous; glaucous. 



(t Low alpine plants 7. -S. rioidum, 



h Krect, densely ctespitose 9. S^^labriim. 



oEi-ect, slender; flowering glume half as long as its awn. 



10. S. inanlare. 



rfSlender; innovations very numerous 13. S. cdspiiosum. 



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