Southeastern Washington and Adjacent Idaho. 81 
Rock Lake are remarkable. Upon the thin soils which seem able 
to support only a Poa-Polygonum community and where even the 
bunch-grass seems dwarfed, pine seedlings establish themselves, 
rooting in the crevices, and eke out an existence for years. On 
the rocks in early August, everything is dry and burned. Even 
Amelanchier, cherry, and Spiraea become defoliated, still the 
pines hold on until relieved by the advent of autumn showers. 
Their stunted condition stands in marked contrast to their well 
developed companions in the more protected places with deeper 
soil. . 
In the. open park-like growth of the yellow pine in the moun- 
tains it is not unusual to find fine clean-boled trees 2.5-3 feet in 
diameter towering above one or two younger generations. In 
other situations the forest is less open, and is then usually mixed 
with Douglas fir. In such situations, as one would expect in a 
transition region from prairie to forest, the ground cover is com- 
posed more largely of prairie than of forest forms. The follow- 
ing lists indicate the more important shrubs and herbs of open 
pine woods: 
Amelanchier florida Rosa gymnocarpa 
Arctostaphylos uva-ursi Rosa nutkana 
Ceanothus sanguineus Salix scouleriana 
Holodiscus discolor Spiraea corymbosa 
Opulaster pauciflorus Symphoricarpos racemosus 
Pachistima myrsinites Vaccinium macrophyllum 
Prunus emarginata 
Achillea millefolium lanulosa Aster conspicuus 
Agropyron spicatum (including Astragalus mortoni 
var. inerme) Bromus marginatus 
Anemone piperi Calamagrostis rubescens 
Antennaria dimorpha Campanula rotundifolia 
Antennaria luzuloides Deschampsia elongata 
Antennaria racemosa Deschampsia calycina 
Apocynum pumilum Drymocallis convallaria 
Arnica cordifolia Epilobium angustifolium 
8I 
