IV 



CONTENTS. 



V. The Sandhills Sxtbclimax. 



PAGE 



Redfieldia flexuosa 68 



Calamovilfa longifolia 68 



Andropogon hallii 70 



Muhlenbergia pungens 70 



Sporobolus cryptandms 71 



Eriogonum microthecum 71 



Artemisia filif olia 73 



Tradescantia virginiana 73 



PAGE 



Heliotropium convolvulaceum 74 



Petalostemon villosus 74 



Gilia longiflora 75 



Euphorbia petaloidea 76 



Psoralea lanceolata 78 



Ipomcea leptophylla 78 



Sandhill Root Systems and the Sandhill 



Environment 79 



VI. The Gravel-Slide Community. 



Krynitzkia virgata 81 



Paronychia jamesii 82 



Aletes acaulis 83 



Apocynum androssemifolium 84 



Smilacina stellata 85 



Pachylophus csBspitosus 85 



Thlaspi alpestre 86 



Mentzelia multiflora 87 



Eriogonum flavum 87 



Gravel-Slide Root Systejns and Gravel-Slide 



Environment 88 



VII. The Half-Gravel-Slide Community. 



Elymus triticoides 92 



Solidago oreophila 92 



Rubus deliciosus 93 



Besseya plantaginea 94 



Geranium caespitosum 95 



Calamagrostis purpurascens 95 



Kceleria cristata 95 



Gilia aggregata 95 



Potentilla arguta glandulosa 97 



Frasera speciosa 97 



Aster porteri 98 



Half-Gravel-Slide Root Systems and the 



Half-Gravel-Slide Environment ... 98 



VIII. The Fore.st Community. 



Pirola chlorantha 100 



Thalictrum fendleri 100 



Erigeron asper 101 



Erigeron macranthus 101 



Fragaria virginiana 102 



Allium cernuum 103 



Aralia nudicaulis 103 



Opulaster opulifolius 103 



Ribes lacustre 104 



Rosa acicularis 104 



Arctostaphylos uva-ursi 105 



Senecio cernuus 105 



Castilleia miniata 105 



Heuchera parvifolia 105 



Saxifraga bronchialis 106 



Haplopappus parryi 107 



Forest Root Systems and the Forest 108 

 Environment. 



IX. ECADS. 



Smilacina stellata 110 



Chamaenerium angustifolium 110 



Elymus triticoides 112 



Bouteloua gracilis 112 



Stipa comata 113 



Yucca glauca 114 



AUionia linearis 114 



Abronia fragrana 115 



Kceleria cristata 117 



Chrysopsis villosa 117 



Euphorbia montana 119 



Root Modifications of Polydemics 121 



Summary- . 



X. Summary. 



. . 122 I Bibliography 



128 



