Hitchcock — Studies on Subterranean Organs. 137 



Vicia Americana, Muhl. Slender rhizomes. Prairie. 



Lathyrus ornatus, Nutt. Extensive, slender, branching, 

 horizontal rhizomes, more or less winged like the stem. 

 Sand-hills. 



Apios tuberosa, Moench. Rhizomes which enlarge into 

 tubers at intervals of an inch or so, or even several inches. 

 The tubers send out new rhizomes and also may produce 

 vegetative stems, near the end. Shoots may arise in succes- 

 sive years from the same tuber. Moist thickets and low 

 ground. 



Cassia Marylandica , L. Forms a crown. Low ground. 



Desmanthus brachylobus, Benth. A thick, woody tap-root 

 supporting a large crown. Low ground. 



Schrankia uncinata, Willd. A vertical, woody, sunken 

 root, surmounted by one or more woody, knotty stems, from 

 the summit of which grow the several slender vegetative stems. 

 Prairie. 



Prunus Watsoni, Sarg. Roots produce buds abundantly. 

 Sand-hills. 



Geum album, Gmelin. A slowly creepiug oblique rhizome 

 about an inch long. Flowering stems axillary. New bud 

 terminal at base of vegetative shoot. Woods. 



Agrimonia mollis, Britt. A slowly creeping rhizome, the 

 new plant just beyond the old. Woods. 



Agrimonia parvijlora, Ait. Offsets formed at base of old 

 stem. Woods. 



Rosa Arkansana, Porter. Extensive rhizomes. Prairie. 



Penthorum sedoides, L. Base decumbent and rooting. 

 In the autumn rosettes or offsets are produced, which elon- 

 gate into vegetative shoots the following spring. Wet places. 



Ly thrum alalum, Pursh. New stems arising from the base 

 of old. Moist places. 



Ludwigia alternifolia , L. Forms buds at base of old stem. 

 Springy places. 



Oenothera Missouriensis, Sims. A fleshy-woody sunken 

 root throws up one or more stems each of which forms a 

 crown at the surface. Limestone hills. 



Oenothera serrulata, Nutt. A woody crown, forming buds 

 along the base of the old stem. Prairie. 



