Natural Orders.'] 
APPENDIX. 
55 7 
existing between the surfaces of the two joints in some species. I con- 
sider it, however, as absolutely proved by an unpublished genus of this 
order, having an involucrum nearly similar to that of Euphorbia, and like 
it, inclosing several fasciculi of monandrous male flowers, surrounding 
a single female ; but which, both at the joint of the supposed filament, 
and at that by which the ovarium is connected with its pedicellus, has 
an obvious perianthium, regularly divided into lobes. 
UMBELLlFERiE.* This order maybe considered as chiefly Euro- 
pean, having its maximum in the temperate climates of the northern 
hemisphere; in the corresponding southern parallels it is certainly much 
less frequent, and within the tropics very few species have been observed. 
In Terra Australis the Umbelliferae, including a few Arab®, which be- 
long at least to the same natural class, exceed 50 species. The greater 
part of these are found in the principal parallel, in which also those genera 
deviating most remarkably from the usual structure of the order occur. 
The most singular of these is Actinotus of LabillardiereA which differs 
from the whole order in having a single ovulum in the unimpregnated 
ovarium. A second genus, which I shall hereafter publish with the 
name of Leucolauna , is worthy of notice on account of the great apparent 
differences of inflorescence existing among its species ; which agree in 
habit, in the more essential parts of fructification, and even in their re- 
markable involucella. Of this genus, one species has a compound umbel 
of four many flowered radii ; a second has an umbel of three rays with 
two or three flowers in each ; several others, still retaining the compound 
umbel, which is proved by the presence of their involucella, have from 
four to two single-flowered rays : and lastly one species has been observed, 
which is reduced to a single flower ; this flower, however, is in fact the 
remaining solitary ray of a compound umbel, as is indicated by the two 
bracteee on its footstalk, of which the lower represents the correspond- 
i 1 1 o ■ leaf of the general involucrum, while the upper is evidently similar to 
the involucellum of the two-rayed species of the genus. 
* Jus . gen. 218. 
f Nov. holl. pl. spec. 1 . p: CJ. t. 92. Eriocalia Smith exot. hot. 2 ,p. 37- 
