Remarks on the structure of the Fruit of Rhipsalis. 469 
On the Structure of the Fruit of Rhipsalis. 
The fruit of Rhipsalis has been considered to possess a different 
structure from that of all other Cacteae, in having placentae in the 
axis of the berry instead of on the paries, and the berry itself has 
also been considered as probably trilocular, whilst those of all other 
genera in the order are unilocular. Hence De Candolle has placed 
it in a separate tribe, his Rhipsalidese, expressing, however, some 
doubts about the accuracy of the observations upon which he has 
founded his arrangement. In his last memoir on the Cacteae (1834,) 
he separates Rhipsalis salicornioides from the rest, under the generic 
name of Hariota ; and in that species he states that he had ascer- 
tained the ovary to be unilocular, arid the placentae parietal. I have 
lately had an opportunity of examining the fruit of Rhipsalis c.y- 
sytha in all stages of its growth, and can safely assert that both 
suppositions, of its being trilocular and having central placentae, 
have originated in a mistake. When the fruit is ripe, the seeds 
are nestled in the midst of a very liquid pulp, and are no longer 
attached to any part ; but in earlier stages of its growth, they are 
found to adhere in double rows upon three placenta?, disposed lon- 
gitudinally on the paries. At .first sight there is a deceptive ap- 
pearance of three dissepiments, or at least of three inwardly pro- 
jecting placentae, to the innermost extremities of which the seeds 
are attached ; but further examination shews this to arise, mere- 
ly from the close agglomeration of the funicular 
chords (see Fig. A,) which stretch from the paries 
towards the axis, and from whose extremities the 
ovules are suspended in a reversed position. The 
placentae themselves scarcely form any projection 
on the paries, as is very evident in some cases 
where many of the ovules have become abortive ; A 
and, indeed, several are so in all cases, and then appear as small 
brown spots attached to the paries. It seems to me likely that the 
watery pulp in which the seeds are nestled in this and other genera 
of the order is derived from the super- developement of the cellular 
tissue of the funicular chords. The whole coat of the berry, form- 
ed by the union of the calyx tube and pericarp, is very succulent, 
but the interior pulp is much more so ; and this does not appear 
any way connected with, or to originate from the inner coats of the 
pericarp, but in the way here suggested. Be this as it may, it is 
sufficiently evident that the ovary and fruit of Rhipsalis are strictly 
unilocular with parietal placentae, as in all other Cacteae, and, con- 
sequently, it is necessary that the tribe Rhipsalideae should be sup- 
pressed. 
NO. v. H h 
