348 BETULACEAE 



clusters of 2 to 7, slender, 2 to 3 (or 5) inches long; sepals 2 to 4, most com- 

 monly 3, often unequal, one usually very small when the number is 4 ; stamens 

 2, less commonly 3; pistillate catkins 3 to 7 in a cluster, erect or ascending, 



5 to 6 lines long, in fruit becoming ovoid and 5 to 9 lines long; nutlets 

 flattened, 1 line broad. 



Banks of rivers and perennial streams: Sierra Nevada canons; Sacramento 

 and San Joaquin valleys ; Coast Ranges except in the narrow coast strip occu- 

 pied by the Red Alder; cismontane Southern California as far south as the 

 Cuyamaca Mts. ; northward to the Cascades of "Washington (eastern slope) 

 and northern Idaho. Grows in the lower Sacramento country within a few 

 feet of sea-level, thence practically continuous to 6,500 feet and 8,000 feet in 

 the southern Sierra Nevada, a remarkable altitudinal range. 



Eefs. ALNUS RHOMBIFOLIA Nuttall, Sylva, vol. 1, p. 33 (1842), type loc. vicinity of Mon- 

 terey, Nuttall; Watson in Bot. Cal. vol. 2, p. 80 (1880), in part; Jepson, Fl. W. Mid. Cal. 

 p. 139 (1901). A. oWongifolia Watson in Bot. Cal. vol. 2, p. 80 (1880) in part. 



2. A. rubra Bong. RED ALDER. Tree commonly 30 to 90 feet high, usually 

 with very white or white-mottled bark; trunk unbranched for 15 to 60 feet. 

 1 to 2% feet in diameter; leaves 2 to 6 inches long, elliptic-ovate, often rusty 

 beneath, with coarse teeth which are again finely toothed, the entire margin 

 with a narrow underturned edge ; staminate catkins stoutish, 3 to 7 inches long ; 

 calyx with 4 stamens, but sometimes with 3, especially at upper end of catkin ; 

 pistillate catkins 4 to 6 lines long, maturing into oblong-ovoid cones % to IVs 

 inches long; nutlets flattened, acutely margined or some narrowly winged, 

 roundish, 1 to 1% lines broad. 



Deep cool canons or moist flats from the Santa Inez Mts. north to the Santa 

 Cruz Mts., Oakland Hills, Point Reyes Peninsula, and so on along the coast 

 far north to southern Alaska. With us most abundant in Marin, Mendocino 

 and Humboldt cos., where it forms pure groves of singular beauty in marshy 

 bottoms near the sea. Wood used for fish-barrels, bungs for oak-barrels, buggy- 

 boxes, brake-blocks and in cabinet work. 



Eefs. ALNUS RUBBA Bongard, Veg. Sitcha, p. 162 (1833), the type coll. by E. H. Mertens 

 at Sitka. A. oregona Nuttall, Sylva, vol. 1, p. 28, pi. 9 (1842) ; Jepson, Fl. W. Mid. Cal. 

 p. 139 (1901). 



3. A. tenuifolia Nutt. MOUNTAIN ALDER. Small tree or shrub 8 to 14 feet 

 high; leaves roundish to ovate, thickish, at base truncately rounded (or even 

 subcordate) to cuneate, coarsely toothed and again finely serrate, 1 to 3 inches 

 long; staminate catkins 3 or 4 in a cluster, 3 inches long; stamens 2 to 4, not 

 exceeding the 4 sepals; pistillate catkins 3 to 8 in a cluster, sessile or with 

 peduncles almost 2 lines long; cones small, 3 to 7 lines long. 



Sierra Nevada from Donner Pass northward to Mt. Shasta, thence westward 

 to Trinity Summit ( W.L.J. no. 2058) and the Siskiyous, forming thickets on wet 

 hillsides or in moist hollows at 5,000 to 7,000 feet. Ranges north to the Yukon 

 Territory, thence south through the Rocky Mts. to New Mexico. Also in 

 Lower California. 



Eefs. ALNUS TENUIFOLIA Nuttall, Sylva, vol. 1, p. 32, t. 10 (1842), the original specimens 

 from the Eoeky Mts., and Blue Mts. of Oregon, Nuttall. A. incana var. virescens Watson in 

 Bot. Cal. vol. 2, p. 81 (1880). 



4. A. viridis DC. var. sinuata Regel. THIN-LEAF ALDER. Slender shrub 



6 to 10 feet high; leaves round ovate, thin, gummy when young, bright green, 

 sharply or laciniately toothed, 2^4 to 3 inches long ; catkins appearing in spring 

 at the same time as the leaves, the peduncles of the pistillate leafy at least at 



