46 
REMARKS ON THE NATURAL ORDER ASCLEPIADEiE ; 
WITH SOME 
DIRECTIONS FOR GROWING THE PERGULARIA ODORATISSIMA. 
This is a tribe of plants which differ materially from most others of the vege- 
table kingdom, particularly in the structure of its fertilising" organs. The subjects 
of this tribe belong to the fifth class and second order of the Linnean system, viz. 
Pentandria Digynia, but they occupy a section of it by themselves, inasmuch as 
they have characters in which they all agree, but which stamp them with peculiar 
interest. They also form an order in the natural system, and this is represented 
by the genus from whence it derives its title, Asclepiadece, from asclepias, or 
swallow-wort. 
This order comprises about twenty-five genera, a family among which the most 
noted are Periploca, that beautiful hardy climber wherewith the trellised fronts and 
balconies of some rural villas are decorated ; Asclepias, the type, which contains 
several interesting herbaceous perennials, natives of America; and some pretty 
annuals of ready culture. Sfapelia, a most extensive family of succulents, possess 
the very disagreeable property of emitting a powerful stercoraceous or putrescent 
odour, which even deceives while it attracts the common blow-fly. Hoya, that 
elegant climber, whose blossoms appear as if they were modelled out of wax, or 
from some vegetable substance of a very beautiful texture ; and finally our Pergu- 
laria, also a climber, which yields to none other for the singularity of its habits and 
the astonishing diffusibility of its great fragrance. 
The Asclepiadece agree in having the stamens more or less concealed, and sur- 
mounted by a member which forms a sort of crown, and of this peculiarity of struc- 
ture Hoya furnishes one of the best examples. 
The pollen or farina is not a powder, as that of flowers in general, but is pro- 
duced in waxy or glutinous masses, and in this one point it approximates to the 
Orchidece, or plants of the Orchis tribe. The flowers of all the genera have but 
one petal, which is below or inferior to the fruit, and that is a follicle, or seed-vessel, 
somewhat resembling a folded leaf, opening when ripe by one suture only, of which 
the fruit of the larkspur may be adduced in illustration. 
Pergularia is distinguished from its congeners by its yellowish green flowers, 
produced in large tufts from the axils of its heart-shaped leaves ; these flowers have 
a wheel-shaped contort corolla, the segments somewhat reflexed, and their edges 
folded back ; the tube swollen at the top. Calyx in five segments, shorter than the 
tube; masses of ^o//en erect, small, and requiring a glass to be accurately investigated; 
stigma obtuse, closely invested by the small anthers or pollen. The verdant tufts 
of flowers are formed rather widely apart, in the twining stems ; the individual 
