>UXFLOWER FAMILY. 549 



Involucrate leaves obspatulate, 3 or 4 times longer than the head 



1. P. tenellus. 

 Involucrate leaves oblong to lanceolate, 1 to 2 times as long as the head : 

 var. brei'issimus of . . . 2. P. Oreganus. 



1. P. tenellus Nutt. Prostrate, the forking stems forming a 

 dense mat 3 to 10 in. broad; leaves obspatulate, mucronate, 4 to !-- 

 lines long; heads numerous, 2 lines wide; achene about J line long, 

 oblong or slightly broader toward the summit. 



Valleys and low hills: Coast Ranges; Sacramento Valley; San 

 Joaquin Valley(?). June. 



2. P. Oreganus Nutt. var. brevissimus. Dwarfish, the stems 

 prostrate, several to many from the base but mostly simple, 1 to -5 in. 

 long; leaves oblong or some obspatulate, obtuse or merely acute, the 

 involucrate ones partly concealing the heads; heads comparatively 

 few, 4 to o lines broad, more loosely woolly than in the preceding; 

 staminate flowers about 7 or 8; achene cylindrical or slightly clavate, 

 less than 1 line long. — (P. brevissimus Xutt.) 



Dry beds of vernal pools: Elmira (Solano Co.) to Madrone (Santa 

 Clara Co.). May-June. 



70. EVAX 6;>?rtn. 

 Dwarf rigid densely woolly annuals with entire leaves. Heads 

 with disk-flowers only; pistillate flowers at base of slender columnar 

 receptacle, the male flowers above, all subtended but not enclosed by 

 bracts. Bracts of the pistillate flowers and bracts of the involucre 

 becoming hardened, persistent. 



Heads' mostly scattered . . . . 1. £. sparsifiora. 



Heads in terminal clusters . . . 2. E. cauUsct:n>. 



1. E. sparsifiora. Erect, 1 to 4 in. high, sometimes simple, 

 commonly branching from the base, the heads in the axils, scattered 

 along the branches or slightly glomerate at the ends of the branches; 

 leaves spatulate, narrowed to a very slender petiole, 4 to 7 lines long; 

 bracts of the receptacle woolly on back and rather densely long- 

 hirsute at base, especially the upper; staminate flowers in center 

 about 4. — (Hesperevax sparsifiora Greene.) 



Dry sterile soil: Healdsburg; xv'apa Valley. 



2. E. caulescens Benth. Stem simple or with few long branches 

 from the base, 2 to 8 in. high; heads aU in a terminal hemispherical 

 cluster, f in. broad and surrounded by a. whorl of many leaves; 

 leaves spatulate-obovate, 1 to IJ in. long, the eauline similar but 

 smaller. 



SiKTamento Valley. 



Var. humilis (Hesperevax humilis Greene. Evax acaulis Greene.) 

 One or 2 in. high, the heads crowded on the short central stem or at 

 the ends of the very short horizontal branches (none in the axils), the 

 close clusters subtended by rosulately arranged leaves. — Antioch. 



71. FILAGO li. 



Low woolly annuals with entire leaves and small discoid heads in 



