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XVIII. Revision of the Genus Cassia. By Guorcr BENTHAM, Esq., F.R.S., P.L.S. 
Read March 4th, 1969. 
(Plates LX.-LIII.) 
THE genus CAssIa has frequently been the subject of the special researches of mono- 
graphists. The medical importance of its principal products, Senna-leaves and Fistula- 
fruits, have rendered the investigation of the species from which the best supplies are 
obtained necessary on the part of pharmacologists. The great beauty of many of the 
trees and shrubs it includes is well appreciated, not only in tropical plantations and 
gardens, but also in those of Southern Europe, and, indeed, as far north as Paris, where a 
few species, chiefly, I believe, C. corymbosa and its allies, are amongst the most conspicuous 
of the autumn-flowering shrubs; and although we rarely see any in this country, yet it 
is probable that when our subtropical gardens become more general, Cassias will assume 
their appropriate places in them. — To botanists it presents an excellent instance of a large, 
widely distributed, much varied, but well-defined group. So natural, indeed, is the genus 
that, notwithstanding the great contrast in habit between the splendid arborescent Fistulas 
and some of the weedy herbaceous Prosospermas, or Chamæcristas, and although its prin- 
cipal characters are derived from the pod and the anthers, which both present more 
diversity than in any other Leguminous genus, yet there is hardly a species which has 
ever, by any tolerably fair botanist, been falsely or carelessly included in or rejected from 
the genus, except perhaps in the case of a few garden seedlings which had not yet 
flowered. . | 
One result, however, of the early attention given to the genus has been the large 
number of imperfectly described species, or, at any rate, of so-called species, which it is 
exceedingly difficult to identify. This circumstance, and the very large increase which 
the genus has recently received, obliged me, in working up the Brazilian species for 
Martius's great ‘Flora,’ to go through the whole genus with all the care I could bestow 
upon it. As a result of my investigations I beg to lay before the Society a systematic 
enumeration of the whole genus, observations on old species, and descriptions of new 
ones from the extra Brazilian regions of America or from Asia, with some general ob- 
servations on systematic arrangement and geographical distribution, referring for sys- 
tematic details of Brazilian species to the Cæsalpinieous volume of Martius's * Flora’ about 
to be sent to press, of African species to the second volume of Oliver's * Flora,” now far 
advanced, and of Australian species to the second volume of my * Flora Australiensis'*, 
* [It is now two years since this paper was read: I have since been enabled, during a visit I made in the autumn 
of 1869 to Paris, Geneva, and Munich, to verify a number of synonyms which had remained doubtful; and my account 
of the Brazilian Cæsalpinieæ being now at length published, and the greater part of the second volume of Oliver's 
“Flora ? being already in type, I have been able to refer to both these works throughout the systematie enumeration, 
which I have endeavoured to bring down to the present time. I have thought it right to leave the preliminary ob- 
servations precisely as they were read to the Society.—A pril 1871.] 
