THE PKAIEIES 223 



Croton capitatus Miehx. 



Geranium carolinianum L. 



Houstonia minima Beck. 



Hypericum gentianoides (L.) BSP. 



Opuntia Rafinesquei Engelm. 



Sphenopholis obtusata var. lobata (Trin.) Scrib. 



Sporobolus neglectus Xash. 



Finally the list of plants which seem to be practically restricted 

 to the sandy areas should be presented to complete the record. 

 These plants are not included in the table. 

 On both the sand-dune areas: 

 C3?perus Schweinitzii Torr. 

 Eragrostis pilosa (L.) Beauv. 

 Paspalum setaceum Michx. 

 Strophostyles helvola (L.) Britt. 



On sand-dunes in Harrison county : 



Lespedeza capitata var. longifolia (DC.) T. & G. 

 Lygodesmia rostrata Gray 



On sand-dunes in Muscatine and Louisa counties: 

 Agrostis hyemalis (TTalt.) B. S. P. 

 Aristida tuberculosa Xutt. 

 Asclepias amplexicaulis J. E. Smith. 

 Cristatella Jamesii T. & G. 



Croton glandulosus var. septentrionalis Muell. Arg. 

 Eragrostis pectinacea var. spectabile Grav. 

 Froelichia floridana (Xutt.) Moq. 

 Mollugo verticillata L. 

 Monarda punctata L. 



Physostegia virginiana var. arenaria n. var.20 

 Polanisia graveolens Eaf. 

 Polanisia trachysperma T. & G. 

 Rhus canadensis var. trilobata (Xutt.) Gray. 

 Sporobolus asper (Michx. ) Kunth. 



^Physostegia virginiana var. arenaria n. var. 

 This form of this more or less variable species is evidently an ecological 

 variety, differing from the type, which inhabits low grounds, by the 

 narrow linear or lance-oblong very coriaceous pale-green leaves, the thick 

 coriaceous, lance-ovate bracts which are terminated by a short hard 

 cusp, by the very pubemlent calyx, bracts and upper part of the flowering 

 stem. This variety is locally common on the sand mound in Muscatine 

 and Louisa counties south of Muscatine, and exhibits its response to the 

 xerophytie surroundings by its more rigid, harsher and more or less re- 

 duced leaf and stem structures. 



