Hitchcock — Studies on Subterranean Organs. 139 



Asclepias tuberosa, L. A strong woody or slightly fleshy, 

 vertical or oblique root, with crown at summit. Prairie. 



Asclepias incarnata, L. A small crown with a dense clus- 

 ter of slender fibrous roots. Wet places. 



Asclepias Cornuti, DC. Produces buds upon the roots but 

 not abundantly. Usually there is a long oblique or horizon- 

 tal main root with several stems growing from it, each of 

 which may become a crown. Moist places. 



Asclepias verticillata, L. Roots produce buds. Also a 

 crown is formed at the base of the old stem. Prairie. 



Asclepias stenophylla , Gray. A few inches below the sur- 

 face is a slender, fleshy root a few inches long and half an 

 inch thick which ends abruptly in a long, slender tap-root. 

 A vertical rootstock extends to the surface where a crown may 

 be formed. Prairie. 



Enslenia albida, Nutt. Buds upon creeping horizontal or 

 vertical root. Moist soil. 



Lithospermum hirtum, Lehm. Tap-root with crown. Sand- 

 hills. 



Lithospermum canescens, Lehm. A slender branched, 

 woody root supporting a slender crown. Prairie. 



Lithospermum angustifolium, Michx. A slender fleshy 

 vertical root about half an inch in diameter. Buds from 

 sunken summit or from base of old stem. Prairie. 



Onosmodium Carolinianum, DC. var. molle, Gray. A 

 woody crown upon a woody tap-root. Prairie. 



Convolvulus Sepium, L. Rhizomes creeping a few inches 

 to two feet below the surface. Moist places. 



Convolvulus arvensis, L. Buds upon slender, creeping 

 roots. The roots may be several inches below the surface and 

 send up stems which produce buds along the underground 

 portion thus giving the impression that the plant propagates 

 from rhizomes. A weed in cultivated soil. 



Solanum Carolinense, L. Root slender and usually extend- 

 ing vertically to a depth of four or five feet. Stems are pro- 

 duced above from adventitious buds. Open ground. 



Physalis Virginiana, Mill., lanceolata, Michx., longifolia, 

 Nutt. In the three species studied there is a deep-seated 

 slender root similar to Solanum Carolinense. In old plants the 



