49 
EXOGONIUM Purga. 
The true Jalap plant. 
PENTANDRIA MONOGYNIA. 
Nat. ord. ConvoLvuLacra. (Binpweeps, Vegetable Kingdom, 
p. 630.) 
EXOGONIUM.— Sepala 5. Corolla tubulosa. Stamina exserta. 
Stylus 1. Stigma capitatum, bilobum. Ovarium 2-loculare, loculis 2-ovu- 
latis. Herbs aut suffrutices volubiles America orte. — Choisy in DeCand. 
Prodr. ix. 346. 
E. Purga; foliis sagittato-cordatis acuminatis glabris, pedunculis subuni- 
floris petiolorum longitudine, limbo corollz lato plano. 
E. Purga, Benth. pl. Hartw. 46. 
Ipomoea Purga, Wenderoth Pharmac. centralbl. 1.457. Lindl. FI. med. 809. 
Choisy, I. c. Bot. Reg. 1839. mise. 136. 
Ipomea Schiedeana, Zuccarini Flora, 1831. p. 801. 
Convolvulus officinalis, Pelletier. 
This is the true Jalap plant; that is to say, the species 
of Bindweed which inhabits woods near Xalapa, in Mexico, 
whence the name, and where the tuberous purgative roots are 
collected, dried, and sent to Europe for medical use. The 
‚plant now figured was obtained on the spot by Mr. Hartweg, 
for the Horticultural Society, with whom it flowered in June, 
1846. 
But it would be a great mistake to suppose, that Jalap, 
or a substance analogous to it, is not obtained from other 
plants. We have already shewn that the Ipomeea batatoides, 
figured in our Volume for 1841, t. 36, is another, called the 
Purga Macho ; and it appears from an unpublished letter of 
Don Juan de Orbigozo, that a hairy leaved plant bears the 
same name. In truth, the whole order of Bindweeds possesses 
the properties of Jalap in a more or less marked degree. If 
we do not employ the creeping roots, or the seeds, of the 
species that grow in our hedges, it is only because exotic 
plants are more active. 
