54 University of California Publications in Botany [Vol.9 



altitude of the upper limit of the Canadian in the Yosemite district, 

 though here in places Hudsonian elements are found at lower eleva- 

 tion, as at Snow Flat on the Tioga Road (8,700 feet). In the moun- 

 tains of Tulare County, the Canadian rises to elevations of 9,500 to 

 10,000 feet. The area between these altitudinal limits comprises the 

 greater part of all the high mountain country, within which certain 

 peaks and ridges north of Sonora Pass and a fairly continuous area 

 to the southward rise into the higher zones. But this Canadian area 

 is itself not uniform, at least two subzonal divisions being easily recog- 

 nized : the Jeffrey Pine belt and the true Canadian flora above. 



The Jeffrey Pine belt, which, besides the tree designating this 

 division, includes the bulk of the Abies magnifica forest, constitutes 

 an intermediate phase between the Transition flora and that of the 

 true Canadian. Many of the plants often seen in the Transition are 

 also present here and not a few of the species, common in the true 

 Canadian, send stragglers dowoi into this lowest section of the high 

 mountain flora. There are, however, a number of plants which are 

 distinctive of this lower Canadian belt : 



Habenaria sparsiflora Selinum capitellatum 



Habenaria unalaschcensis Barcodes sangiiinea 



Populus trichocarpa Gilia aggregata (typica) 



Eriogonum spergulinum Apocynum androsamaefolium var. 



T, . , pumilum 



Prunus emarginata ^ 



^ ^, -, , , Pedicularis semibarbata 



Oeanothus eordulatus .^^ . „ . . , 



Hemizonella minima var. parvula 



Ceanothus velutinus Clirysopsis Breweri 



Oenothera xyloearpa (only southern Orochaenactis thysanoearpa (only 



Sierra) southern Sierra) 



The Jeffrey Pine belt is dominated by the forest type of vegeta- 

 tion; therein being allied to Transition flora; with the true Canadian 

 begins that recession of the forest and increasing importance of the 

 meadow characteristic of high mountain floras. 



The Hudsonian zone to the north of Mariposa County is found only 

 on the upper slopes of the peaks and ridges and nowhere in the north- 

 ern portion of the range forms connected areas of considerable size. 

 At the north end of the range, the Hudsonian is present only on the 

 very summits of the high peaks of western Plumas County (Spanish 

 Peak, Bucks Mountain, Mt. Pleasanf^") and is not again found till 

 the region of Long Lake is reached near the Plumas-Sierra county line. 

 From the Gold Lake region southward, the islets of the Hudsonian 

 flora occur more frequently and begin to spread out along the summits 



