[Annals N. Y. Acad. Sci., Vol. XVIII, No. 6, Part II, pp. 181-203. 11 May, 1908.] 
THE NORTH AMERICAN SPECIES OF THE GENUS IPOMCEA. 1 
By PIomek Doliver House, B. S., M. A. 
Introduction. 
A comparative study of specimens of the Convolvulacece, representing 
the species placed by Linnaeus 2 in Ipomosa and Convolvulus, shows that 
the two groups as there constituted, are far from homogeneous. The type 
of Convolvulus is Convolvulus major albus, Tournefort, pi. 17 = (Convolvulus 
sepium L.). The species included in Ipomosa by Linnaeus do not accord, 
except in part, with the diagnosis given by him in the Genera Plantarum 
(1737), where it is stated that the stamens are exserted, and pi. 39 of Tourne- 
fort 3 is cited. This is Quamoclit foliis tenuiter incisis & pinnatis (=Ipo- 
mcea quamoclit L.). Under most circumstances this would establish it as 
the type of the genus, but it must be remembered that the genus Quamoclit 
was an accepted and valid genus before Linnaeus called it Ipomosa and the 
genus has since been restored to generic rank by Moench. 5 In the 5th. 
edition of the Genera Plantarum (1752), the Tournefort reference to pi. 39 
is still retained, with the addition of u Volubilis Dill. Elth. 318.” The 
first species figured by Dillenius under Volubilis is V. zeylanica pes-triginus, 
pi. 318. }. Jf.ll. (—Ipomosa pes-triginus L.) 
In deference to historical usage and long continued uniformity, the 
writer does not believe it necessary to restrict Ipomosa to the group of species 
typified by Ipomosa quamoclit L., but is inclined to accept the species first 
figured by Dillinius under Volubilis, if it is necessary to designate a type 
for the genus Ipomosa. Without doubt the plant of greatest economic im¬ 
portance is Ipomosa batatas (L.) Lam. but as that was placed in Convol¬ 
vulus by Linnaeus and was known as Batatas 4 in pre-Linnaean literature, 
it has nothing to recommend it as an acceptable type of the genus. If I. 
1 Presented in abstract to the Academy at the regular meeting on 9 March, 1908. Manu¬ 
script delivered to Secretary 10 March, 1908. 
2 Species Plantarum, 1753; ed. 2, 1762-63. 
3 Institutiones rei Herbaria, 1700. 
4 Rumph. Amb. 5: 367. pi. 130. 1750. 
5 Moench, Meth. 453. 1794. 
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