326 COMPOSURE PSIL OCABPHUS 



HESPEREVAX 



T. tenellns Nutt. 1. c. Canescently tomento8e throughout with fine 

 oppressed wool which soon detaches from the stem : stems at length much 

 depressed aud branched, 1-3 inches long: leaves spatulate, 3^-6 lines long: 

 heads very numerous, 2-3 lines in diameter: achenes half-line long, obo- 

 vate-oblong. In low grounds, Washington to California. 



P. Oreganus Nutt. 1. c. Silky-lanate : stems erect, 2-6 inches high, 

 branching from near the ground : leaves nearly linear, attenuate below, 4- 

 6 lines long : heads numerous, 4-6 lines in diameter ; achenes oblong-cylin- 

 draceous; Low grounds and roadsides, Oregon and Washington. 



* * Leaves little, and those subtending the heads seldom at all nar- 

 rowed at base : herbage and especially the heads loosely floccose-woolly 



P. elatior Gray Syn. FJ. i, pt. 2, Supp. 448. P. Oreganus var. elatior Gray. 

 Erect and caulescent, or at length with spreading branches, 3-6 inches 

 high, robust: leaves lanceolate or subspatulate- linear, 6-12 lines long : 

 heads 4-6 lines broad, very leafy-subtended, loosely arachnoid-woolly, the 

 the wool of the fructiferous bracts shorter and mostly close : achenes cylin- 

 draceous. Low places, Willamette and Columbia river valleys. 



P. brevissimus Nutt. 1. c Stems very short, mostly simple: leaves ob- 

 long or lanceolate, 2-5 lines long, seldom surpassing the leaves: heads sol- 

 itary or very few, very woolly : achenes cylindrical or slightly clavate. 

 ^'Plains of the Oregon" Nuttall, to California. 



28 HESPEREVAX Gray Pac. R. Rep. iv 101, t. ii. 



Low annuals with mostly opposite leaves and small heads of 

 inconspicuous flowers. Heads discoid, many-flowered ; the pis- 

 tillate flowers with filiform corolla in several series on a convex 

 villous and centrally elevated columnar receptacle, each subtend- 

 ed by an ovate barely concave chartaceous chaffy scale : herma- 

 phrodite but sterile flowers several on the apex of the columnar 

 receptacle, involucrate by a whorl of 3-7 coriaceous open bracts. 

 Bracts of the involucre resembling the chaff of the receptacle. 

 Pappus none. 



H. brevifolia Greene Fl. Fr. 102?. Evax caulescem ^Gray in part. Floc- 

 cose-woolly : stems 4-12 lines high, simple, or "branching from the base, 

 often depressed : leaves lanceolate, 4-6 lines long, tapering into a slender 

 petiole: leads inconspicuous, in sessile terminal or axillary clutters, 

 or solitary, a line or two long : chaffy scales of the receptacle, becoming 

 rigid, those subtending the sterile flowers thicker and woolly inside : 

 achenes obovate-oblong with a narrowed base, straight, more or less com- 

 pressed parallel to the subtending chaff, very smooth. Dry barren spots 

 in prairies, southwestern Oregon and California. 



Subtribe ii Gnaphalese Less. Syn. 269. Heads discoid, heteroga- 

 mous or androgynous or diceciously homogamous; the hermaphro- 

 dite or staminat* flowers when in the same head much fewer than 

 the pistillate ones; pistillate flowers with filiform tubular corolla 

 shorter than the style; the staminate flowers with style or style -bran- 

 ches mostly truncate, all usually with capillary pappus. Recepta- 

 cle without bracts or chaff. Bracts of the involucre numerous, more 

 or less scnrious or with smrious and often colored or pelaloid sum. 

 <mits. Anthers with slender tails. 



