ROSA PRATINCOLA GREENE 309 



Example 3. Stipules narrow, sepals spreading and glandular- 

 hispid, leaflets seven, stem very prickly, hypanthiunis and pedicels 

 glabrous, inflorescence corymbose. 



Example 4. Stipules narrow, leaflets five to seven, sepals con- 

 nivent and glandular-hispid, hypanthiunis and pedicels glabrous, 

 stem very prickly, flowers corymbose. 



It will be noted that in example 1 there are three exceptions, viz., 

 spreading and pubescent sepals and pubescent pedicels ; in example 

 2 deciduous-prickly stem and seven to nine leaflets ; in example 3 

 spreading sepals and seven leaflets, and in example 4, five to seven 

 leaflets. 



These examples show that one cannot predict concomitant vari- 

 ations. There is no uniformity. One is justified in asking if a 

 R. pratincola does exist which conforms to the general rule in every 

 respect. The following example is a typical R. pratincola. Sepals 

 connivent and glandular-hispid, hypanthiunis and pedicels glabrous, 

 flowers corymbose, stem prickly, leaflets seven to eleven, rhachis 

 pubescent, stipules narrow. 



DISTRIBUTION 



General. — Prairies of the United States and Canada, Manitoba to 

 New Mexico and Texas and Iowa to Colorado. 



Specific locality references outside of Iowa : — Colorado, Indiana. 

 Southwest Minnesota, North Dakota. 



Iowa counties :-^Dickinson, Buena Vista, Iowa, Delaware, John- 

 son, Emmet, Cerro Gordo, Winnebago, Pottawattamie, Woodbury, 

 Harrison, Winneshiek, Shelby, Lyon, Hardin, Calhoun, Webster, 

 Fremont, Monona, Lee, Des Moines, W^apello. 



Reported Iowa counties: — Boone (Diehl), Dickinson (Shimek, 

 Pammel), Emmet (Shimek), Fremont (Fitzpatrick), Harrison 

 (Shimek, Pammel), Johnson (Shimek, Somes), Ida (Macbride), 

 Lyon (Shimek, Boot), Muscatine (Shimek, Pammel), Monona 

 (Shimek, Pammel, Boot), Sioux (Shimek), Sac (Macbride), Story 

 (Shimek, Pammel), Woodbury, Winneshiek, Polk, Palo Alto, Clay, 

 Kossuth, Winnebago, Allamakee, Clinton, Scott, Decatur (Pammel). 



ECOLOGY 



The four species which were studied in the field, viz., R. pratin- 

 cola, R. virginiana, R. Woodsii, and R. hlanda, grow in xerophytic or 

 semi-xerophytic habitats. The division of the leaf surface into small 

 leaflets, thick cutin, water-storage cells, compact palisade tissue, 

 hairs and glands are all good adaptations for preventing too rapid 



