W5 



ACTINEAS AND RUBBERWEEDS 



Acti'nea spp. 



Actinea is a fairly large American genus of annual, biennial, or 

 perennial herbs belonging to the sneeze weed tribe (Helenieae) of 

 the aster, or composite family (Asteraceae, or Compositae). Rep- 

 resentatives of the genus occur in all the Western States except 

 possibly Washington, ranging from the Sierra Nevada and Cascade 

 Mountains to southern Alberta, Saskatchewan, the Dakotas, western 

 Kansas, and Texas, to South America. In the United States, 

 these plants appear chiefly on dry, open sites and on rocky slopes 

 from the plains and western deserts to* the ponderosa pine belt in 

 the mountains. Some species occur at higher elevations with a few 

 above timber line. The genus is best developed, both from the stand- 

 point of abundance and maximum number of species, from central 

 Colorado southward through western Texas and the Southwest. 



Approximately 40 species and at least 6 definite varieties of 

 Actinea occur in the Western States. The genus name is derived 

 from the Greek aktu or aktinos, a ray, referring to the petallike, 

 marginal ray flowers of the head. The small to comparatively large 

 flower heads somewhat resemble those of sunflowers ; the ray flowers, 

 present in most species, are yellow. Probably the most reliable tech- 

 nical characters which distinguish this genus from other members 

 of the Compositae are the 5 (sometimes 6 to 12), thin-papery, often 

 sharp-pointed, scales (pappus), which crown the top-shaped, mostly 

 five-angled, hairy body of the seedlike fruits (achenes) ; the close 

 overlapping (rather than spreading) of the two- or three-rowed 

 bracts (involucre) at the base of the flower head, and the absence 

 of chaffy bracts between the individual flowers (*. e., the "receptacle" 

 is naked) . The genus is a complex one, displaying a degree of varia- 

 tion which has led many authorities to separate it into a number of 

 segregated genera. Actineas may be silky-hair}^, woolly, or hair- 

 less (glabrous). Many of the species are without true stems, the 

 leaves being basal, and the flower heads solitary on leafless stalks 

 (scapes) ; others are leafy-stemmed, with alternate leaves, and nu- 

 merous, clustered flower heads. The leaves may be entire-margined 

 or variously cleft and divided ; some are glandular-dotted. 



In addition to Actinea, "Actinella" of American authors (not 

 Pers.), Hyinenowys (syn. Piwadenia), Macdougalia, Rydbergia, and 

 Tetraneu/ris have been used as generic names, and one or more of 

 these generic names are recognized in most of the current manuals, 

 depending upon the conception of the various authors as to the seg- 

 regation of the groups involved. However, Dr. S. F. Blake, an out- 

 standing expert in Compositae in the Bureau of Plant Industry, 

 United States Department of Agriculture, has advised the Forest 

 Service that species occurring in Mexico show that these segregated 

 groups, or genera, intergrade and, therefore, should, in his opinion, 

 be considered as belonging to the one genus, Actinea. Recognition of 

 the characters which distinguish these segregated groups, or genera, 

 is helpful in understanding the genus as a whole, especially in dis- 

 criminating between poisonous and nonpoisonous species. 



