Hitchcock — Ecological Plant Geography of Kansas. 61 



Most of these have strong woody tap roots which penetrate 

 the clefts in the rock. Two have bulbs ( Camassia, Zyga- 

 denus). Four are annuals (Amphiachyris, Heliotropium, Eu- 

 phorbia, Croton), the others perennials or biennials. 



Certain shrubs often give a peculiar physiognomy to thehills, 

 especially along the margins of woods which often follow up 

 the ravines. These are Ceanothus ovalus, Rhus glabra, R. 

 Canadensis, Oomus asperifolia, Symphoricarpus vulgaris. 

 None of these are, however, confined to the hills, but grow 

 freely in open woods or even along the streams. Juniperus 

 Virginiana is rarely found except along these limestone hills. 



In the western part of the State the species change though 

 the physiognomy remains the same. 



Clematis Fremonti (central Kansas only), Stanleya pin- 

 natifida, Lesquerella ovalifolia, Psoralea cuspidata, Dalea 

 aurea, Petalostemoii lenuifolius, Astragalus Missouriensis, 

 Oenothera Fremontii, O. Hartwegi, Mentzelia ornata, Aster 

 Fendleri (on gypsum hills onlv), A. ericaefolius, Melampodi- 

 um cinereum, Zinnia grandijiora. , Riddellia tagetina, Acti- 

 nella scaposa linearis, A. acaulis, Gilia rigidula acerosa, Pent- 

 stemon albidus, Scutellaria Wrightii, Paronychia Jamesii, 

 Eriogonum long folium, Euphorbia lata, E. Fendleri, Yucca 

 angustifolia (also on barren sandy-clay hills). 



All perennials or {Mentzelia) biennials. Shrubs are pres- 

 ent only in the canons or ravines, they are Rhus Canadensis 

 trilobata, Prunus Resseyi. 



It will be observed that most of the plants of the rock flora 

 are perennials, that they have reduced leaf surface, narrow 

 as in Aciinella scaposa linearis, bract-like as in Paronychia 

 Jamesii, cut into small divisions as Peucedanum, compound 

 with small leaflets as Dalea ; or if the leaves are not partic- 

 ularly small they are thick and leathery as in Clematis and 

 Pentstemon Cobaea; or that they are hairy, Lesquerella ovali- 

 folia (stellate hairs), Oenothera Missouriensis (silky hairs), 

 Mentzelia (very rough tuberculate). Plants with running 

 root-stocks are very uncommon. 



