18 THE AMERICAN BOTANIST. 



Forms of the Arrow Head. — The common arrow- 

 head is a well-known and variable plant. It was for many- 

 years known as Sagittaria variabilis but more recently is called 

 ^S. latifolia. When it was known as 5". variahilis a large num- 

 ber of the more striking forms were named as varieties and 

 when the craze for hair-splitting began it was inevitable that 

 many of these should become new species. Two closely re- 

 lated forms were described in 1894 as S. Engelmanniana and 

 S. longirostra, respectively and many botanists have since con- 

 sidered them distinct species, but last year K. K. Mackenzie 

 discovered at Forked River, N. J., a lot of specimens in which 

 the distinctive characters of the two forms are so blended that 

 he is constrained to believe the two to be but forms of a single 

 species. Thus does another species become extinct. Not the 

 least remearkable fact in this connection is that the reduction 

 was made in Torreya. 



Cereus giganteus. — The New York Sun recently con- 

 tained the following: "Since the giant cactus, which is by 

 far the most impressive feature of the desert vegetation of the 

 Far Southwest, was studied and named by Dr. George Engel- 

 mann in 1847, it has been known to botanists as Cereus gigan- 

 teus. Now Dr. L. N. Britton and Dr. J. N. Rose of the New 

 York Botanical Garden have found that it is not a cereus at 

 all, but belongs to a separate genus of which it is the only 

 species. They propose to name the genus Carnagiea in honor 

 of Andrew Carnegie." Commenting upon this Horticulture 

 of Boston observes, "Undoing one another's work has long 

 been a passion with many of our esteemed friends, the botan- 

 ists, and genus and species splitting their ever-besetting sin. 

 The establishment of this monotypie genus in honor of the 

 Laird of Skibo looks questionable. With all due respect to 

 the learned gentlemen mentioned in the above extract, we are 

 disposed to credit Dr. Engelmann and our German con- 

 temporary, Schumann, with a better knowledge of the spiny 



