176 Flora of the Palouse Region 



Akenes 4-5-ribbed. 296. taraxacum. 



Akenes 10-ribbed. 297. troximox. 



Akenes not beaked. 



Pappus copious, while and soft. 300. CREPIS. 



Pappus a single row of rough tawny bristles. 



301. HIERACHM. 



Tribe 2. AMBROSIEAE. 



Staminate and pistillate flowers in the same head: involucre of a few rounded 



bracts. 302. iva. 



Staminate and pistillate flowers in separate heads: involucre of the pistillate 

 heads bur or nut-like. 

 Involucral-bracts of the staminate heads united: involucre of the pistillate 

 heads with a single series of tubercles and prickes. 



303. AMBROSIA. 

 Involucral-bracts of the staminate heads separate: involucre of the pistil- 

 late heads an oblong bur. 304. XAXTHIUM. 



Tribe 3. ASTEROIDEAE. 



Ray-flowers none. 307. bigelovia. 



Ray-flowers white, purple or blue, never yellow. 



Involucral-bracts in 2-5 rows, with herbaceous tips. 



310. ASTER. 

 Involucral-bracts in 1-2 rows, never with herbaceous tips. 



311. ERiGERO.w 

 Ray-flowers yellow. 



Pappus of 2-8 rigid and early-falling awns. 305. grixdeua. 



Pappus of copious slender or capillary bristles. 



Pappus double, the outer row very short. 306. chrysopsis. 



Pappus simple. 



Bristles of pappus copious and unerpual, somewhat rigid. 



308. APLOPAPPUS. 



Bristles of pappus equal and nearly in a single series, slender. 



309. SOLIDAGO. 



Tribe 4. IXULOIDEAE. 



Receptacle chaffy. 312. psilocarphus. 



Receptacle naked. 



Staminate and pistillate heads on different plants. 



313. AXTEXXARIA. 



Pistillate and perfect flowers in the same head; staminate flowers none. 



314. gxaphalium. 



Tribe 5. HELIANTHOIDEAE. 



Ray-akenes obcompressed. 



Disk-akenes obcompressed. 320. BIDKNS. 



Disk-akenes prismatic-quadrangular <>r laterally compressed. 



316. BAI.SAMORRHIZ A. 



Disk-akenes slender and abortive. 322. lagophylla. 



Rav-akenes laterally compressed. 



Disk-akenes 4-angled or laterally compressed. 



Ray-flowers fertile, rarely wanting: heads small. 



321. MADIA. 



Ray-flowers neutral, rarely wanting: heads large. 



