250 UNIVERSITY OF MISSOURI STUDIES [39^ 



44. Arabis hirsuta (L.) Scop. Hairy rock-cress. 

 Boone county (Tracy). 



New Brunswick to British Columbia; Georgia to Cali- 

 fornia: Europe and Asia. 



45. Hesperis matronalis L. Dame's rocket. 

 Naturalized in Boone county (Tracy). 

 Europe and Asia, thence to North America. 



46. Spiraea salicifolia L. Meadow-sweet. 

 Boone county (Tracy). 



Newfoundland to the Rocky Mountains; Georgia to 

 Missouri: Europe and Asia. 



47. S. tomentosa L. Steeple-bush. 

 Boone county (Tracy). 



Nova Scotia to Manitoba; Georgia to Kansas. 



48. Mespilus hyemalis Walt. [Crataegtis flava Ait.]. 

 Summer haw. 



Boone county (Tracy). In 1897 I gathered specimens of 

 a haw that I took to be this, but the material has been lost. 

 Virginia to Missouri; Florida to Texas. 



49. M. spathulata (Michx.) Poir. [C. spatlmlata Michx.]. 

 Small cock-spur thorn. 



Boone county (Tracy). 



Virginia to Missouri; Florida to Texas. 



50. M. Oxyacantha (L.) Crantz \C. Oxyacantha L.]. 

 English hawthorn. 



Boone county (Tracy). 



Europe and Asia, thence to North America. 



51. M. pirifolia (Soland.) Desf. \C. tom.e?itosa pyrifolia 

 (Soland.) Gray]. Pear-leaved thorn. 



Boone county (Tracy). 



New Jersey to Ontario and Michigan; Georgia to Mis- 

 souri. 



52. Rosa Carolina L. Swamp rose. 

 Boone county (Tracy). 



Quebec to Minnesota; Florida to Mississippi and Mis- 

 souri. 



