340 
Arber — On the Nature of the ‘ Blade ’ in 
the tendrils separate from the petiole — the petiolar tissue begins to be 
penetrated- by a single invagination (i.) passing from the ventral surface 
between two of the vascular bundles: This stage is seen in Fig. 14 A in 
the case of the petiole marked pet . 2 , to which the tendrils t. 2 and t'. 2 are 
still attached. A little higher, where the tendrils have separated from the 
petiole, this invagination is found to have passed more deeply into the 
tissues, following a curved path, so that the future form of the ‘ lamina ’ is 
already indicated (/. 3 in Fig. 14 A and f. in Fig. 14 B). In older leaves 
(Figs. 14 C-F) we can follow the further development of the invagination, 
which — in association with a wing-like outgrowth^of the two newly formed 
leaf margins, marked with crosses in Fig. 14 c — is responsible for the 
ultimate shape of the ‘ lamina’. 
Rhipogonum. 
By the kindness of Mr. J. H. Maiden, F.R.Sl, I have been able to 
examine young shoots of Rhipogonum album , R. Br., from the Botanic 
Gardens, Sidney, N.S.W. Microtome sections, through the stem apex bearing 
young leaves, show that in this plant the leaves have no broad basal sheath, 
but the petiole seems to be attached directly to the axis. This petiole 
passes into the ‘lamina’ by a gradual process — becoming broader and 
thinner the farther it departs from its level of attachment to the stem (cf. 
pet. in Fig. 16 A, with f. in Fig. 16 B). It will be recognized, on comparing 
Fig. 1 6 with Figs. 14 and 15, that both in the general ontogeny of the leaf 
and in the origin of the ‘ lamina ’, there are much wider divergences between 
Smilax and Rhipogonum than one might naturally expect, considering that 
the latter genus — with Heterosmilax — is assigned to the tribe Smilacoideae. 
The differences are indeed of so essential a nature as to suggest a doubt as 
to- the close affinity assumed to exist between Smilax and Rhipogonum — 
a doubt which is not set at rest by a consideration of the reproductive shoots 
of the two genera, for Rhipogonum differs from Smilax not only in its 
hermaphrodite flowers, but also in the characters of the inflorescence. 
LlLIlFLORAE — Amaryllidaceae. 
Curculigo. 
Cttrculigo is one of the few Monocotyledons, outside the Palms and 
Cyclanthaceae, which have a broad plicate leaf-limb. Just as in the case 
of these groups, the plicate appearance of the blade of Curculigo has 
hitherto been attributed to folding. 1 But, as Figs. lJ.B, D, and F show, the 
ultimate leaf-form in C. recitrvata , Dryand., is due, in reality, to a series 
of alternating dorsal and ventral invaginations of the petiole (or sheath). 
The ‘ lamina ’ development strikingly recalls that of Veratrum , already 
described (pp. 337-9) ; we find here precisely the same arrangement of a ventral 
sinus opposite the median bundle, • 'm.b ., and four other parallel ventral 
1 Hirmer, M. (1919). 
