1921] Smiley: Flora of the Sierra Nevada of Calif or ni^a 61 



than in any other pteridophyte family except Selag'inellaceae, where 

 the single genus Selaginella is monotypic. A notable fact connected 

 with the pteridophyte element in the Sierran high mountain flora is 

 the exclusion of the genus Lycopodium, which has 5 boreal species in 

 Washington/^ one of which {L. annotinum L.) ranges southward in 

 the Kockies to Colorado in the same latitude as the Sierra. The 

 Pinaceae include 4 genera: Abies and Tsiiga, monotypic; Juniperus 

 with 2 species, and Pinus with 6 species. Here again there is a sig- 

 nificant difference between the flora of the mountains of the Pacific 

 Northwest and of the Rockies and of that of the higher Sierra. All 

 of the genera and all of the species, except Pinus Balfouriana, P. 

 flexilis, and Abies niagnifica, present in our region, are also boreal 

 elements in Washington, but of the 20 species of g\Tiuiosperms present 

 in the northern Cascades, 10 attain their southern limit on the 

 Cascade-Sierran axis at some point to the north of our region, though 

 some of them continue down the Rocky Mountains to our latitude or 

 even attain lower latitudes in New Mexico and Arizona. The char- 

 acteristic northern gymnosperm genera Picea and Larix have no 

 representatives in the Sierra Nevada though both are found in the 

 Cascades, Larix coming south to Mt. Hood and northwest Montana, 

 and Picea to northern California along the Cascades, and in the 

 Rockies to New Mexico and Arizona. 



Of the 51 families of Angiosperms, the largest, both in number 

 of genera and species, is Compositae. This great family, of world-wide 

 distribution, has within our limits 32 genera and 91 species. Of its 

 genera Erigeron is the largest, having 12 species in the Canadian life- 

 zone or above, followed by Senecio with 9 species. Aster and Arnica 

 each with 7, and Artemisia with 6. All the other genera of Compo- 

 sitae, resident in the higher Sierra, have 5 or fewer species {Haplo- 

 pappus 5; Chrysothamnvs, Antennaria, Hieraciiim, each 4; Hulsea, 

 3 ; Helenium, Eriophyllum, Chaenactis, Raillardella, Achillea, Cir- 

 sium, Agoseris, and Crepis, each 2 ; the remaining 14 genera, or nearly 

 one-half of the total, are monotypic). 



The family- having the next largest number of genera is Gramineae, 

 with 18 genera, Poa and Agrostis, each with 5 species, being the two 

 largest. The remaining 28 species of grasses in the high mountains 

 include 4 in Calamagrostis, and 3 each in Trisetum and Agropyron; 

 the other genera have 2 or 1 each, there being 8 monotypic genera, 

 or again nearly one-half of the total number of genera of grasses. 



After Compositae, the family with the largest number of species 

 is Cyperaceae, the 4 genera of which are divided into 52 species, the 



