130 CLIMAX FORMATIONS OF WESTERN NORTH AMERICA. 



Frmmnal Soeittitt: 



Cans pennaylvanioa. 

 AntHinaria dioeoa. 

 A none patww. 

 AiMtnone oaroliniana. 

 Lomatium fooniculaceum. 

 Draba caroliniana. 

 Androsaee ocddentalis. 



Vtmal Soeietiea: 



Astragalus crassicarpus. 

 Ara$;alu8 lamberti. 

 Tradcscantia virgiaiana. 

 Phlox pilosa. 

 Anemone canadensis. 

 Fragaria virginiana. 

 Viola pedatifida. 

 Viola cucullata. 

 Baptisia leucophaea. 

 Callirrhoe alcaeoides. 

 Vicia americana. 

 Thalictrum purpurascens. 

 Ranunculus ovalis. 

 Zizia aurea. 

 Anemone cylindrica. 

 Ekiuisetum arvense. 

 Comandra umbellata. 

 Senecio aureus. 

 SisjTinchum angustifolium. 

 Lithoepennum linearifolium 

 Lithoflpermum canescens. 

 Lithospermum hirtum. 

 Agoseris cuspidata. 

 Achillea millefolium. 

 Hosackia americana. 

 Viola pedata. 

 Sieversia ciliata. 

 Hypoxia hirsuta. 

 Oxalis stricta. 

 Castilleia sessiliflora. 

 Houstonia angustifolia. 



Soeietiea of the True Prairie. 



BbUvoI Societiet: 



Psoralea tenui flora. 

 Amorpha canescens. 

 Petalostemon candidus. 

 Petalostenion purpureus. 

 Psoralea argophylla. 

 Erigeron ramosus. 

 Glycyrhiza lepidota. 

 Brauneria pallida. 

 Lepachys columnaris. 

 Helianthus rigidus. 

 Dalea laxiflora. 

 Verbena stricta. 

 Verbena hastata. 

 Linum sulcatum. 

 Equisetum levigatum. 

 Equisetum hiemale. 

 Veronica virginica. 

 Allium mutabile. 

 Pentstemon grandiflorua. 

 Euphorbia coroUata. 

 Coreopsis palmata. 

 Rosa arkansana. 

 Lespedeza capitata. 

 Monarda fiatulosa. 

 Heliopsis scabra. 

 Pycnanthemum lanceolatum 

 Pentstemon gracilis. 

 Silphium integrifolium. 

 Steironema ciliatum. 

 Teucriimi canadense. 

 Teucrium occidentale. 

 Amorpha nana. 

 Callirrhoe involucrata. 



Serolinal Societie*: 

 Solidago rigida. 

 Aster multiflorus. 

 Solidago missouriensis. 

 Solidago spceiosa. 

 Artemi.sia frigida. 

 Grindelia squarrosa. 

 Gutierrezia sarothrae. 

 Kuhnia glutinosa. 

 Aster oblongifolius. 

 Artemisia graphalodes. 

 Artemisia dracunculoides. 

 Salvia azurea. 

 Rudbeckia hirta. 

 Solidago serotina. 

 Aster sericeus. 

 Aster paniculatus. 

 Aster novae-angliae. 

 Aster azureus. 

 Nabalus asper. 

 Eupatorium altissimum. 

 Liatris pycnostachya. 

 Liatris punctata. 

 Liatris scariosa. 

 Carduus undulatuB. 

 Solidago nemoralis. 

 Solidago canadensis. 

 Vernonia baldwinii. 

 Vernonia fasciculata. 

 Helianthus maximiliani. 

 Helianthus grosse-serratxia 

 Silphium laciniatum. 



CLANS. 



Clans are climax communities of limited area or dominance. They usually 

 occur as secondary areas in societies, but are occasionally found where the 

 dominance of grasses is too great to permit the appearance of societies. A 

 clan may consist of a species which is locally important or conspicuous, but 

 does not occur generally. The most common type is represented by a gre- 

 garious species which grows in small patches of a few square yards or a few 

 rods. Another common type is exemplified by subsparse secondary species 

 which are more or less frequent throughout the association. Some of these 

 naturally become so sparse that they no longer give any impression of a com- 

 munity. Clans are perhaps best regarded as conmiunities of the third degree 

 of dominance, in which the control is necessarily slight as a consequence of 

 being subordinated to the primary control of the grass dominants and the 

 secondary control of the subdominants. Near the edges of an association, 

 societies of adjoining areas enter in reduced abundance and dominance. As 

 a result, they have the appearance of clans and would pass for such where a 



