70 
DESCRIPTIVE LIST OF NEW PLANTS. 
biennial, growing from two to three feet in height if planted in 
any good rich garden soil. It is well suited for cultivation in 
the open borders, as a summer annual. The seed should be 
sown on a little heat in February, and afterwards treated as half- 
hardy annuals are. The flowers are produced in whorls, the 
upper portion of each is white, having a blush of yellow on the 
front of each petal, and the keel is bright blueish purple. It 
flowers during the latter part of summer and autumn, and was 
raised in February 1846, from seeds received from Mr. Hartweg, 
said to have been collected on the mountains near Anganguco, 
in Mexico.— -Bot. Reg. 11-47. 
ConvolvulacEjE. Pentandria Monogynia. 
Exogonium purg a (Bentham). Although Jalap has been used 
in European medicine for nearly two centuries and a half, it is 
only within a few years that its botanical source has been cor¬ 
rectly ascertained. The plant long cultivated as yielding the 
true jalap, in the stoves of Europe, and among the rest in the 
Botanic Gardens at Edinburgh, is the Convolvulus Jalapa of 
Linneeus and Willdenow, or Ipomcea machroriza of Michaux, a 
native of Yera Cruz. But between the years 1827 and 1830 it 
was proved by no less than three independent authorities, M. 
Ledanois, a French druggist, resident at Orizaba, in Mexico; 
Dr. Coxe, of Philadelphia, through information supplied by Mr. 
Fontagnes, an American gentleman, who lived at Jalapa; and 
Schiede, the botanical traveller, from personal examination, that the 
drug of commerce is obtained, not from the hot plains around Yera 
Cruz, but from the cooler hill country near Jalapa, about 6000 feet 
above the level of the sea, where it is exposed to frost in winter 
time, and that the plant which yields it is an entirely new species. 
Schiede introduced the plant for the first time into England, and 
it has been cultivated in various botanic gardens of Germany. 
In this country it was probably first grown in the Botanic Garden 
of Edinburgh, from a tuber sent by Dr. Coxe, of Philadelphia, 
to Dr. Christison, in 1838. 
The plant belongs to the genus Exogonium of Choisy, as defined 
in De Candolle’s ‘ Prodromus,’ although the author places it 
under the genus Ipomcea , from which it is at once distinguished 
by its exserted stamens. It grows on the mountains of Mexico. 
