330 IOWA ACADEMY OF SCIENCE 



Opuntia polyacantha Haw. Abundant in arid sections, but of 

 uneven distribution, being quite wanting over large areas 

 and in some places the dominant species. 



Gaura parviflora Dougl. Common especially in the sandy 

 strip along the Columbia. 



EpiloMum angustifolium L. One small specimen along the 

 Columbia. 



EpiloMum paniculaium Nutt. Infrequent in moderately dry 



ground. 

 Epilobium adenocaulon Haussk. Very common in wet ground. 



Oenothera biennis muricata (L.) Lind. Two specimens were 

 found along the Columbia representing, apparently, two 

 strikingly different "mutants" of this confused group. 



Anogra pallida (Lindl.) Britt. An abundant and character- 

 istic species of the low sandy strip along the Columbia. 



Boisduvalia densiflora (Lindl.) Wats. Found sparingly along 

 the Umatilla. 



Myriophyllum sp. In alkaline pools; scarce. 



Daucus pusillus Michx. Scarce, along the Umatilla. 



Pteryxia terebinthina (Hook.) C. & R. Frequent in dry sand. 



Berula erect a (Huds.) Cov. Frequent in swampy places. 



Centaurion exaltatus (Griseb.) Wight. Very common in wet 



places. 

 Asclepias speciosa Torr. Scarce, in damp ground. 

 Asclepias mexicana Cov. Scarce, in moderately dry ground. 

 Phlox sp. A single specimen in dry soil. 



Gilia inconspicua (Smith) Dougl. Frequent, in moderately 

 dry soil. 



Navarretia intertexta (Benth.) Hook. Scarce, in damp ground 

 near the Umatilla. 



Phacelia sp. Common in moderately dry to very dry ground. 



Conanthus parviflorus Greenm. Infrequent, in dry ground. 



Coldenia nuttallii Hook. Frequent in dry ground. 



Heliotropinm curassavicidum L. Abundant in slightly moist, 

 usually somewhat alkaline soil. 



