20 Expeditio7i to the 



an inch in length, and about one fourth of an inch in breadth, 

 rising considerably and bearing a cluster of radiating spines. 

 At their insertion, these thorns are surrounded by pungent 

 setae, as in C. ferox. The whole plant is so thickly beset 

 with strong spines pointing in every direction, that no ani- 

 mal of any considerable size, can approach it unharmed. It 

 does not form thickets, but each plant is a cluster by itself, 

 and when first seen at a distance, they were mistaken for 

 bisons. We were informed by one of our engagees, who had 

 travelled into the Spanish provinces as far as Monterey, that 

 this plant is common there, and its fruit much esteemed. 



The Cacti are considered characteristic of warm and dry 

 climates, like those of Egypt and California> Perhaps there 

 is no part of the world, where plants of this family, consti- 

 tute so large a proportion of the vegetable products of the 

 soil, as in the arid plains of the Arkansa. These plains are 

 sufficiently dry, but like those of the Platte and Upper Mis- 

 souri, where cacti are almost equally abundant, they are vi- 

 sited by severe cold in winter. 



Another highly interesting plant, which occurs in the most 

 barren and desolate parts of the plain, is a cucurbitaceous 

 vine, resembling some of our common squashes, bearing a 

 small fruit, which is round and smooth, and as large as an 

 oraDge. It is perennial, having a somewhat ligneous root, 

 four or five inches in diameter, and descending often more 

 than four feet into the earth. We were so fortunate as to 

 meet with it in flower, and also with ripened fruit. It has 

 the acutely margined seed of the Genus Ciicumis^ but in 

 other respects, is closely allied to cucurbita.f In addition 



* Humboldt's Personal Narrative, Vol. i. p. 362. Philadelphia edition. 



f Cucumis? perennis, American colycinth. 



Calyx seated upon the germ, rugose, coloured, campanulate, exterior 

 divisions subulate. 



Masc. Three filaments short and closely cohering, coTering the cen- 

 tral disc. 



Fern. Style short; stigmas three — bipartite. 



