260 REV. G. HENSLOW ON THE ORIGIN OF PLANT-STRUCTURES 
GERANIACE has seven species of Erodium growing in the 
Desert; while the British autogamous species Geranium dissectum, 
G. molle, Erodium moschatum and E. cicutarium are common in 
the cultivated districts; FE. cicutariwm having also established 
itself in the Desert as well. In the one or two species of 
Erodium which I have had the opportunity of examining, as also 
of Monsonia nivea, the pollen-tubes were visible, the pollen 
having evidently escaped from the anthers which were crowding 
round the stigmas. 
Lreeuminos£.—Of this order the genus Astragalus is the most 
typical, being represented by fourteen species in the Deserts. 
The flowers of A. bombycinus (Pl. XII. figs. 18, 14) are about one 
inch in length; but in other species they are very minute, the 
stigmas in all cases being pollinated by the anthers of the same 
flower and often before the flower expands (e. g. A. mareoticus, 
A. tribuloides, and A. Siebert, Pl. XII. fig. 15). In the larger 
flowers of .A. bombycinus, in order to place the stigma in the 
midst of the anthers the long style is bent in the form of the 
letter N (Pl. XII. fig. 18), a feature which would seem to indicate 
tbat ancestrally the style was curved and elevated above the 
stamens as in the English Broom. A similar adaptation to self- 
fertilization occurs in Cassia obovata (Pl. XII. figs. 11, 12), one 
of the two species of this genus found in the Deserts. This has 
small, very conspicuous brownish flowers, half an inch in length. 
In this flower some of the anthers are very small, twisted, and 
appear to be abortive, others are elongated on excessively short 
filaments and stand erect around the ovary. The style is bent 
abruptly downwards at its base, having the stigmatic end up- 
turned, so that the pollen can fall directly upon it. There is no 
true stigma but a “jagged edge” to the stylar orifice ; a not dis- 
similar degradation is found in Linaria Helava (P|. XII. fig. 27) 
and Pulicaria arabica (Pl. XII. fig. 16) of the same Desert *. 
UmBeriirer#.—This order is only represented in the Deserts 
by one or two plants, of which Pityranthus tortuosus is perhaps 
the commonest. This plant has extremely minute flowers in 
small umbels. The anthers shed their pollen while still incurved 
over the stigmas. 
Composit m.—Several characteristic plants of this order are 
* A somewhat similar structure occurs in the “monstrous” Myosotis alpes- 
tris, var. “ Victoria,” in cultivation, as described in the ‘Journal of the Royal 
Horticultural Society,’ vol. xvi. 1898, pp. xxv, xxvi. 
