1922.] REVISION OF CALIFORNIA ARCTOSTAPHYLI 85 



Ref. — Arctostaphylos pumila Nutt. Trans. Am. Phil. Soc. 

 ser. 2, 8:266 (1843), type loc. Monterey, Nuttall. 



14. A. nummularia Gray is a dwarf of the flat "pine barrens" 

 of the Mendocino coast, and is associated with dwarf states of 

 Pinus muricata and Cupressus pygmaea. This species does not, I 

 think, crown-sprout, but after fires seedlings appear abundantly 

 on its area. Mr. Carl Purdy tells me that these seedlings flower the 

 second year. 



Locs. — Fort Bragg, Jepson, W. C. Mathews; Mendocino City, 

 Bolander 4749; Albion, Davy & Blasdale 6068. 



The plant of Amador Co., described by Parry as A. myrtifolia, 

 does not seem specifically distinct and it is here disposed as var. 

 myrtifolia Jepson n. comb. 



Locs. — lone, K. Brandegee; betw. lone and Buena Vista, Cong- 

 don. 



Refs. — Arctostaphylos nummularia Gray, Proc. Am. Acad. 

 7:366 (1868), type loc. Mendocino plains, Bolander. Var. myrti- 

 folia Jepson. A. myrtifolia Parry, Pitt. 1 :35:(1887), type loc. ridges 

 e. of lone, Parry. 



15. A. sensitiva Jepson n. sp. is a medium-sized erect shrub 33^2 

 to 5 feet high. It grows on Mt. Tamalpais, and has passed hitherto 

 under the name A. nummularia. The true A. nummularia Gray of 

 the Mendocino coast is a low or almost mat-like plant. Arctosta- 

 phylos sensitiva is very shallow-rooted and is one of the most re- 

 markable of all species of the chaparral in its relation to fire. The 

 individuals are completely killed in chaparral fires and do not crown- 

 sprout. In very intense fires the shrub may be completely consumed ; 

 in fires of less intensity or governed by suddenly changing air- 

 currents a shrub may be killed by the high temperature generated 

 in its vicinity without any evidence associated with destruction 

 by fire. Such shrubs, retaining all their leaves, but with the foliage 

 brown and dead, stand on the margin of fire-swept bands in the 

 chaparral, as if suddenly electrocuted without any visible sign of 

 injury to the plant as a whole. The shallowness of the root-system 

 increases measurably the chances of its mortality in running fires. 

 It tends to colonize exclusively small areas on Mt. Tamalpais. 

 After fires it reappears promptly on "burns," and fruits at the age 

 of five or six years. It thus adapts itself to short fire-intervals and 

 is a true fire-type shrub. 



Locs. — Mt. Tamalpais, Jepson (type), Herbert &f Wieslander; 

 betw. Butano and Little Butano creeks, Santa Cruz Mts., Dudley. 



Refs. — Arctostaphylos sensitiva Jepson. A. nummularia 

 Jepson, Fl. W. Mid. Cal. 370 (1901), not of Gray. 



16. A. canescens Eastw. This species, here regarded as valid, 

 is reduced in the latest revision of this genus (N. Am. Fl. 29:97, — 

 1914) to A. tomentosa Lindl. A. tomentosa is a species of the Wash- 

 ington and Oregon coasts which ranges into California along the 

 north coast. A. canescens inhabits the summits of the middle Coast 



