PRIMARY CHARACTERS IN THE SPECIES OF RHEUM. 295 
nine stamens ; in these the three outer segments are rather smaller 
and comparati ively narrower than the three inner ones. In R. nobile, 
which has six stamens, the segments of the calyx are equal, ‘ainda 
and almost free, so that in this species the floral envelope and the 
andreecium are in a sense homotaxic. The calyx ae up after 
maturation, but ea attached to the base of the 
TAMENS.—These consist of an outer whorl of six, ‘and an inner 
whorl of three ; arse in the case of R. nobile, in which the inner 
whorl is suppressed, as in Oxyria and Rumex. The filaments are 
broadened out at the base, but distinct from one another, except in 
3 australe and fi. Webbianum, where they are united below, and 
ring from a common ring of connective tissue. The antec are 
introns. 
Frurt.—The fruit is a samaroid achene, by Hayne,* atlas 
and Mucntar? { called a caryopsis, by Bentham and Hooker a nut, 
and by Meisner an achene. It is scarcely flat enough to be con- 
sidered a true samara, and the term ‘“‘nucule” is never applied to 
the fruit of a unilocular ovary containing a single seed. Linneeus 
distinctly stated that there was no pericarp ; but in most of the 
speeiee it is of the nature of a thin subcrustaceous covering. The 
mbryo is straight, and slightly excentric; the cotyledons are 
Eiaccs and plane, and the radicle short. In R. nobile, the 
curved cotyledons indicate transition to Nyctaginee 
Taking into consideration the specific affinities, both presto 
and collective, I propose that the first character upon 
bdivision of the genus should be based be the iene an 
attachment of the stamens. Apart from its anomalous habit, R. 
nobile, in being distinguished from all the other species by having 
six stamens, seems to require to be separated from them altogether, 
i 
its subdivisions and these two ceva from the nutritive organs 
will suggest groups of a lower gr 
Several species described br] Miiation ane Babaetoeap writers are 
merely garden forms of tainted origin, and branded ‘ patria ignota.” 
I do not think that the interpolation of such descriptions should be 
allowed to obscure he: systematic affinities of the species in a 
synopsis of the on 
* Darstellung der zne ral Smee Bad. xii. 
+ Illustr. Himal. B 
t Actes d. Congr. isis ‘Bot. Amsterd. 1877, p. 212. 
s The sheet labelled ‘‘ R. Emodi’’ among Wallich’s East Indian plants in 
the Linnean Society’s library contains specimetis of two species mixed up 
penne and it is impossible to tell which specimen Wallich intended to be the 
type. Royle, in his examination of the specimens, has pointed out that one of 
them is the R. australe of Don; it is better, ermrnecite 
confusion, to adopt his name of R. Webbianum for the other. 
