Bailey & Bailey: Woody Plants of National Parks 135 



4. Menzies Spiraea (Spiraea Menziesi 

 Hook.). — Erect shrub, 2 to 6 feet high with red- 

 dish to brown bark; leaves oblong, toothed toward 

 the tip, green and smooth above, somewhat paler 

 below, 1 to 3 inches long; flowers rose-colored, 

 borne at the ends of the branches in dense, narrow 

 clusters 2 to 5 inches long. 



Occurrence. — OLYMPIC: Low Dividn near base of 

 Moun; Seattle, 3,700 feet. MOUNT RAINIER: near Kautz 

 Creek bridge; Nisquall)' Valley. 



5. Douglas Spirae.a (Spiraea Douglasi 

 Hook.), tig. 71. — Similar to Menzies spiraea but 

 the leaves finely and softly white-cottony below. 



Occurrejice. — OLYMPIC: Lake Crescent. MOUNT RAI- 

 NIER, common in swamps or on lake margins. CRATER 

 LAKE, rare, 4,500 to 5,100 feet: North Fork Castle 

 Creek; Annie Creek at south entrance. LASSEN, com- 

 mon at lower elevations. 



RoCKMAT (Petrophytum (Nutt.) Rydb.) 



There are two species of Petrophytum in the 

 western parks. Both are very small herb-like 

 shrubs with prostrate woody stems and dense 

 tufts of small leaves at the bases of the short erect 

 flowering stems. The plants grow commonly on 

 rocks in the mountains and are often found cling- 

 ing in the cracks of perpendicular rock faces. While the plants are very small, 

 the flowers resemble those of the spiraeas and are considered as such by some 

 botanists. They are white and borne in narrow cylindric clusters about I/2 

 to 1^2 inches long. 



Field Guide to the Species 



Leaves 3-nerved, '4 to % inch long, nearly smooth or only sparingly hairy; occurs 



in Olympic National Park 1. P. Henderson!. 



Leaves 1 -nerved, 1/6 to |/2 inch long, hairy; occurs in Sequoia and Southwest parks 



2. P. caespiiosum. 



1. Henderson Rockmat (Petrophytum Hendersoni (Canby) Rydb.) — 

 Low alpine shrub 21/2 to 6 inches high; leaves I/4 to % inch long, mostly 

 smooth or nearly so, forming basal tufts or rosettes at base of flowering stems; 

 flowers small, white, borne in dense cylindric clusters 1 to 2 inches long on 

 erect stems up to about 6 inches high. 



Occurrence. — OLYMPIC, occasional on cliff faces, about 4,000 to 5,000 feet: Mar- 

 tin's Lake northeast of Low Divide; Mount Seattle; Mount Carrie; Lake Constance; 

 Mount Storm King; Mount Angeles; Appleton Peak; Boulder Peak. 



2. Tufted Rockmat (Petrophytum caespitosum (Nutt.) Rydb.).^ 

 Low, prostrate alpine shrub often forming dense cushions or mats several feet 

 in diameter; leaves 1/6 to ^2 inch long or less, more or less pointed at the 



Fig. 71. Douglas spiraea 

 (Spiraea Douglasi). 



