THE SUBCLIMAX CHAPARRAL. 



187 



Cercocarpus parvifolius are lacking. Prunus and Rhus are the most meso- 

 phytic, Purshia the most xerophytic. Amelanchier, Holodiscus, Philadelphus, 

 and Opulaster are more or less intermediate between these two extremes, 

 while Cercocarpus ledifoUus, Peraphyllum, and Ribes are nearly equivalent 

 to Purshia, as is shown by their frequent occurrence as outposts in dense sage- 

 brush. 



SOCIETIES. 



From its nature and position, the societies of the mountain chaparral are 

 largely derived from the climax communities in contact with it. The majority 

 of these come from the grassland, but a number enter also from sagebrush, 

 woodland, and even from the montane forest. The societies of the sunny 

 intervals between the bushes are chiefly those of the ecotone between chaparral 

 and grassland or sagebrush. As a consequence, it is necessary to list here only 

 those which grow in the shade of tall clumps or of a more or less continuous 

 chaparral cover. Some of these have been derived from woodland or forest, 

 but the majority are shade-forms of grassland and sagebrush subdominants. 

 A few of them are grasses, Elymus triticoides, Agropyrum caninum, Bromus 

 ciliaius, Stipa comata, etc., though by far the greater number are herbs. Low 

 shrubs, such as Symphoricarpus occidentalis, Rosa adcvlaris, Rhv^ radicans, 

 Pachystigma, and Berheris often form a characteristic layer. Ruderal annuals 

 are frequent also, perhaps because the denser clumps afford them protection 

 from grazing. 



Vernal Societies: 



Anemone patens. 

 Senecio aureus. 

 Arenaria fendleri. 

 Euphorbia montana. 

 Aragalus lamberti. 

 Erysimum aspenim. 

 Pachylophus caespitosus. 

 Draba aurea. 

 Pentstemon coenileus. 

 Arabia holboellii. 

 Comandra lunbellata. 

 Mertensia lanceolata. 

 Scutellaria reidnosa. 

 Tradescantia virginiana. 

 Vicia americana. 

 Erigeron glandulosus. 

 Litbospermum multiflorum. 

 Delphinium scopulorum. 

 Allium reticulatum. 

 Lappula texana. 

 Smilacina stellata. 

 Thalictrum fendleti. 



Vernal Societies continued. 



Heuchera parvifolia. 



Thermopsis montana. 

 Estival Societies: 



Geraniiun caespitosum. 



Chenopodiimi fremontii. 



Polygonum convolvxilus. 



Polygoniun douglasii. 



Calochortus gimnisonii. 



Potentilla arguta. 



Campantila rotundifolia. 



Pentstemon secundiflonis. 



Pentstemon barbatus. 



Pentstemon unilateralia. 



Pentstemon strictus. 



Galium boreale. 



Erigeron flagellaris. 



Gilia aggregata. 



Achillea millefolium. 



Monarda fistulosa. 



Castilleia integra. 



Castilleia miniata. 



Thelesperma gracile. 



Estival Societies continued 



Potentilla gracilis. 



Erigeron asper. 



Senecio fendleri. 



Lupinus pusillus. 



Sisymbrium incisum. 



Nepeta cataria. 



Epilobium paniculatum. 



Lactuca pulchella. 



Salvia lanceolata. 



Bidens tenuisecta. 



Erigeron canadensis. 



Hedeoma drummondii. 

 Serotinal Societies: 



Artemisia gnaphalodes. 



Artemisia frigida. 



Brickeliia grandiflora. 



Kubnia glutinosa. 



Solidago speciosa. 



Solidago missouriensis. 



Gymnolomia multiflora. 



Aster bigelovii. 



Mirabilis oxybaphoides. 



THE SUBCLIMAX CHAPARRAL. 

 EHUS^UERCUS ASSOCIES. 



Nature. The subclimax chaparral is a fragmentary community of stream 

 valleys and bluffs, due to the shading-out of the eastern forest as it meets the 

 prairies and plains. As a consequence, it is rarely massive, but extends as 

 narrow belts for hundreds of miles along the upper bluffs of the Missouri and 

 its main tributaries. Farther west along the lesser streams, it forms the typi- 

 cal vegetation of the narrow valleys. It is more or less developed in the broken 



