T 27 
Tree (Ginkgo bilob a, Li). 
cut below the point at which the petiole becomes free from 
the pedicels of the ovules the vascular tissue assumes the 
form of a ring of bundles separated by wide medullary rays ; 
at a slightly higher level the ring becomes wider and forms 
an ellipse, and from this several tracheids pass off to form the 
trace of the subtending leaf, which consists of two separate 
collateral bundles, as in the petiole of an ordinary foliage- 
leaf. The remaining bundles are now arranged in two groups 
of two each (Fig. 15), with two rudimentary additional bundles, 
r, r, consisting of radially disposed phloem-elements, but 
very little xylem; these die out at a higher level (Figs. 16 
and 17). A section through the base of the pedicels at the 
level of their separation (Fig. 18) reveals the existence of 
a small bud, b , between the ovuliferous stalks, the inner faces 
of which are clothed with hairs. This small bud explains the 
presence of the two rudimentary bundles, and may be regarded 
as the aborted apex of the flowering shoot which bore the 
two pedicels and their ovules as lateral members. In each 
pedicel there are two collateral vascular strands inclined 
towards one another, as in the double leaf-trace of an 
ordinary petiole ; the centripetal xylem-tracheids and trans¬ 
fusion-elements are however more abundant in the pedicel 
bundles. Fig. 19 represents a transverse section of one of 
the pedicels; it shows two vascular bundles and two large 
canals ; in a section of the same pedicel later at a higher 
level the two bundles have coalesced to form a single strand 
(Fig. 20), which is accompanied by numerous transfusion- 
tracheids and several centripetal xylem-elements. 
PI. IX, Figs. 21-23. In the ordinary female flower in which 
a flowering axis occurs in the axil of a leaf and bears two 
laterally placed ovules at the apex, the subtending leaf and 
the peduncle cohere at the base. A transverse section of the 
coherent petiole and peduncle shows the arrangement of 
bundles represented in Fig. 21 ; the lower part, /, passes up 
into the leaf-stalk and the upper part, f, becomes the peduncle. 
The leaf-stalk possesses the usual pair of bundles and the 
flower-stalk has four bundles in two pairs (Fig. 22); a short 
