158 
CONTRIBUTIONS TO BOTANY. 
involucels. We find also in the inner bark of Ephedi-a, strong 
fibres almost as abundantly as in the Urticacece : another similar 
development invariably occurs in that genus, in the vaginant 
stipulary leaves that surround each branchlet, at the point of its 
origin in the axils. There is some approach in the floral struc- 
ture of the Gnetacea to that of the Urticacece ; that is to say, it 
is in both cases diclinous, the male flower in both families pre- 
senting a gamophyllous perigonium seated generally in its own 
involucel, or occasionally several perigonia within involucels 
more or less confluent with each other. It is true that in Urti- 
cacea the perigonium is often 4- or 5-partite, but it is sometimes 
2- or 3-fid, with equal segments ; the insertion of the stamens is 
invariably at the base of the tubular portion of the perigonium, 
as in Ephedra, and often the filaments are monadelphousiy con- 
joined at their base. In the tribe Forskohlece the involucels of 
the flowers are combined into an annular cup, as in Gnetum ; 
sometimes two involucels, united at the base, contain one or two 
florets, and then the solitary stamen is fixed in the base of the 
perigonial tube, without any vestige of an ovary, as in Gnetum. 
I have stated these numerous points of coincidence in order to 
show that, when we take into consideration the sum of their 
characters respectively, a greater approximation will be found to 
exist between these two families than has been imagined : in 
the present imperfect state of our knowledge, their juxtaposition 
in the system cannot be safely established ; for the Gnetacece 
require a more cai’eful examination. Much additional informa- 
tion may be expected from the promised description, by Dr. 
Hooker, of the new and curious genus Welwitschia, which, I 
have no doubt, will tend greatly to elucidate the question of the 
true affinities of this family. 
Meyer has classed the different species of Ephedra in two 
sections, — the one, Plagiostoma, where the summit of the tubillus 
is obliquely ligulated or unequally two-lobed ; the other. Disco- 
stoma, where it is truncated or enlarged in the form of a disk, 
the latter section comprising only two species, which are of 
South-American origin, E. Tweediana and E. americana. On 
referring to his drawing of the former species (Mem. Acad. St. 
Petersb. tom. v. pi. 7. fig. 9), we find there a representation of 
this tubillus, marked h, which shows no approach whatever to a 
disciform shape ; and in regard to the latter species, which Meyer 
does not appear to have seen, Kunth describes its tubillus as he 
conceived it to be, a “ stylus subulatus exsertus, stigma simplex 
and Richard defines the same as ‘‘rectus, tubulosus, ostiolo 
oblique sub-4-lobo.” In all the specimens of E. Tweediana that 
I have seen, especially in those collected by myself, the tubillus 
is straight, in no degree enlarged at the apex, and generally 
