﻿NOTES ON THE ANATOMY OF THE YOUNG TUBER OF 

 IPOMOEA BATATAS LAM. 1 



Florence A. McCormick 

 (with EIGHT figures) 

 Aside from the interest in it as an economic plant and in the 

 diseases which are so destructive to it, sweet potato {Ipomoea 

 Batatas Lam.), like many of the Convolvulaceae, has an unusual 

 structure in its thickened roots. The anatomy of certain thick- 

 ened stems and roots has been investigated; but, so far as the 

 writer has been able to discover, Ipomoea Batatas has received 

 little attention. 



Historical 



The sweet potato has many scientific names (i, p. 323), among 

 which Ipomoea Batatas Lam. (6), Batatas edulis Choisy (1), and 

 Convolvulus Batatas Linn. (5 and 12) are the most familiar. The 

 origin of /. Batatas is unknown (7), but records of its history in 

 early literature have been written by DeCandolle (4), Gray and 

 Trumbull (8), and Sturtevant (19). 



DeCandolle (4) cites Turpin (20) as having produced con- 

 vincing figures showing that the thickened underground parts 

 of I. Batatas are roots and not stems. The figures are those of 

 entire tubers, both young and old, and they are given for com- 

 parison with the stem tubers of Solatium tuberosum and Helianthus 

 tuber osus. With the rarest exceptions, the tubers of the sweet 

 potato have been considered roots, but Kamerllng (10) has 

 recently taken up the question anew. He reviews the literature 

 in which the sweet potato is mentioned as having thickened roots, 

 and names Haak. as a writer who considers these tubers thick- 

 ened stems. Though Kamerllng did not investigate the young 

 tuber, he regards the tuber of the sweet potato as a thickened stem 

 and not a root, and gives figures upholding this view. Following 

 Kamerllng, Tuylhusa (21) essentially agrees with him. 



1 Contribution from the department of Agricultural Botany, Nebraska Agn- 



