Notes . 
290 
The well-formed and prominent phloem-groups are, on the other hand, 
completely separate from one another. The centre of each group, 
which thus constitutes a distinct stele, is occupied by an intercellular 
space formed by the disintegration of the older elements of the xylem, 
which, however, are still persistent towards each end of the runner. 
Around each stele runs a well-developed and easily demonstrated 
endodermis. 
In Nymphaea tuberosa the stalks which bear the tubers are very 
short, not more than 4 c.m. long, some of the tubers being almost 
sessile. But all cases examined showed essentially the same structure 
as in N.flava , the stalk containing three to five separate steles, each 
composed of three to five vascular bundles, although here the separa- 
tion of the bundles within each stele is much less distinct. 
In all cases, whether the base only of the rhizome becomes tuberous 
(Raciborski, 1. c.), or whether the tubers are borne on shorter or longer 
stalks, and even when the tubers are metamorphosed flower-buds, 
as in Nymphaea Lotus var. monstrosa 1 , at the commencement of the 
next period of vegetation they bear buds, the first or first two inter- 
nodes of which grow out into thin stolons and at their terminations 
swell out to form new rhizomes. In the cases of N flava and blanda , 
these stolons, which may be termed secondary, arise from the buds 
previously mentioned in reference to the former species, as springing 
from the ends of the primary runners. They possess six to seven 
vascular bundles, the arrangement of which differs from one stolon to 
another, and even in the different regions of the same stolon. For they 
may be all separate and distinct, or a varying number of them may unite 
in pairs. When there are only six present, and these unite into three 
pairs, such sections present a striking similarity to those of the floral 
peduncle of Cabomba aquatica , for here also there are six bundles of 
a very similar appearance and united into three pairs. The rhizome 
and floating shoots of Cabomba possess two such pairs only. 
These facts seem to introduce a question as to whether the term 
‘ stele ’ should be applied to these paired bundles or not, for in the 
former case we should have to consider Cabomba, and also Brasenia , 
which is exactly like it, as polystelic plants throughout, excepting their 
petioles. At any rate, we have here in the single order Nymphaeaceae 
all gradations from the undoubted distinct steles found in the primary 
1 Barber, Ann. Bot., Vol. iv, p. 105. 
