IOWA ACADEMY OF SCIENCES. 141 



This differs in a general way from Mercer in being lighter 

 green in color and more oblate in form. 



If we take the market as a criterion of the value of the fruit, 

 the Kentucky Mammoth is certainly a superior crab. Mr. B. 

 A. Mathews (Evolution of Native Fruits, Bailey p. 270), says 

 that in 1890 he had fruit of this tree "which sold at $1 per 

 bushel while good fruit of Grimes Golden, Roman Stem, and 

 others was selling for 50 to 75 cents " 



Regarding the introduction of this crab, B. A. Mathews in a 

 letter to Professor Craig, dated Knoxville, October 29, 1898, 

 says: "I got the Kentucky Mammoth of Charles Downing 

 about twenty-five years ago. Don't know where he obtained 

 it." The name as given to it by Downing would, however, 

 indicate that it came originally from Kentucky. In connection 

 with further study of this crab it would be advisable to obtain 

 specimens of wild crabs from Kentucky. It has been suggested 

 that it is a hybrid; the greasiness of the skin of the fruit, the 

 astringency of flesh and character of flowers strengthen this 

 assumption. 



THE GENUS SALIX IN IOWA. 



CARLETON R. BALL. 



The genus Salix has long and justly been considered a dif- 

 ficult one to study. It is not that the genus is so large, there 

 being only some 200 living species known, or that these spe- 

 cies are so variable in themselves, although a few of them are 

 known to be very much so. The chief difficulty lies in the 

 dioecious character of the plants, and the fact that in the 

 majority of the species the flowers are produced before the 

 leaves appear, or at least before they are large enough to 

 become characteristic. 



A complete specimen of any one species of Salix should 

 include the winter twigs, the flowers, and the mature foliage 

 from both the staminate and pistillate plants, as well as a 

 nearly mature fruiting branch. Not only this, but all the 

 specimens of each sex should be taken from the same individ- 

 ual. When, however, we bear in mind that the majority of 

 specimens in our herbaria, both large and small, present but 

 two of the seven important parts mentioned above, and these 



