PIPER FLORA OF THE STATE OF WASHINGTON. 233 



ERIOGONUM. 



Flowers not stipe-like at base. 



Involucre nerveless; branches leafy; annual 1. E. angulosum. 



Involucre distinctly nerved. 



Outer perianth segments much broader than the inner. 

 Umbel simple, close; plants densely cespitose. 

 ' Involucre campanulate; flowers 3 to 4 mm. 



long, white or yellow 2. E. ovalifolium. 



Involucre turbinate; flowers 4.5 to 5.5 mm. 



long, wine red 3. E. vineum. 



Umbel compound; plants loosely cespitose. 

 Involucres in clusters; flowers white, yellow, 



or purple 4. £^. proliferum. 



Involucres scattered, mostly solitary ; flowers 

 white. 



Plants erect or ascending 5. E. niveum. 



Plant decumbent Q. E. decumbens. 



Outer perianth segments like the inner. 



Shrub, much branched ; leaves linear to oblanceo- 



late 7. E. microthecum. 



Herbs. 



Annuals; stems wiry; leaves rosulate. 



Involucre 3 mm. long 11. £". vimineum. 



Involucre 1 to 1.5 mm. long \2. E. baileyi. 



Perennials. 



Plants very dwarf and very leafy; pe- 

 duncles bearing a single involucre. ... 13. E. minimum. 

 Plants tall, not very, leafy; peduncles 

 bearing more than one involucre. 

 Peduncles stout, fistulous; involu- 

 cres 3 to 6 in each cluster. 



Leaves ovate-oblong, acute, 5 



to 15 cm. long 8. E. elatum. 



Leaves oblong or ovate, obtuse, 



1 to 5 cm. long 9. £". nudum. 



Peduncles slender, nol fistulous; in- 

 volucres scattered in a loose 



cyme 10. £■. sirictum. 



Flowers attenuate and stipe-like at base. 

 Perianth pubescent. 



Involucre with reflexed lobes. 



Prostrate or nearly so, only the flowering stems 

 upright; flowers cream color; leaves oblong 



or spatulate, not revolute 14. £■. douglasii. 



Erect, much branched; flowers bright yellow; 



leaves linear or linear-spatulate, often revolute. 15. E. sphaerocephalum. 

 Involucre with erect lobes or teeth. 



Shrubby; leaves linear, revolute 16. £". thymoides. 



Herbaceous; leaves oblong or obovate, not 

 revolute. 



Flowers yellow; bracts 3 to 8 17. E. piperi. 



Flowers purplish; bracts 2 18. £■. pyrolaefolium. 



Perianth glabrous. 



