OBSERVATIONS ON SOxME OF THE PLANTS EXHIBITED. 281 
OBSERVATIONS ON SOME OF THE PLANTS EXHIBITED. 
By the Rev. Professor G. Henslow, M.A., V.M.H., &c. 
[Delivered December 5, 1899.] 
Retinospora. — Mr. Henslow drew attention to a large collection of 
Conifers exhibited by Mr. Russell. With regard to Retinosporas, botanists 
had not agreed as to their affinities. Bentham and Hooker included 
Betinospora under Chamcecyparis (this being a section of Thuya), because 
the seeds were usually two at the base of each scale, and not many as in 
the Cypress. Others would refer it to Cupressus, because the fruit (a 
** galbulus ") was globular, and not ovoid or elongated as in Thuya. The 
numerous varieties are referable to two species, natives of Japan, viz. 
B. ohtusa and B. pisifera, and are remarkable for dimorphic foliage. In 
the younger state, i.e. as appearing first on seedlings, the leaves are less 
adherent, and more pointed or spinescent. In the later stage the basal 
part of the leaf is adherent for a greater length, while the apex is short 
and obtuse. This latter condition gives a resemblance to a Club Moss, 
hence the specific name Lycopodioides. The more pointed leaf resembles 
that of a Heath, and has suggested the specific name Erlcoides. The 
origin or cause of these two types of leaf appears to be climatal, since 
analogous forms appear in many different plants growing in such condi- 
tions as tend to arrest development of the foliage. The Club Moss type 
is seen in various plants of arctic, antarctic, alpine, and desert regions. 
One of the most instructive is the genus Veronica in New Zealand, 
species of which on high elevations assume precisely similar forms of 
foliage. 
Under cultivation in good soil, and in our milder and moister 
climate, the arresting conditions are non-existent. The foliage, there- 
fore, often tends to assume its more primitive form. Thus in 
Betinospora and Juniperus the minute leaves become replaced by the 
longer pointed form ; while in the Azores Juniperus brevifolia has leaves 
like those of the Yew. Veronica cuprcssoidcs sometimes acquires a lobed 
herbaceous type of leaf under cultivation. 
Yews. — Mr. Henslow compared the ordinary form of this tree bearing 
horizontal boughs and leaves with that of the Irish or fastigiate variety, 
on the branches of which, as they are erect, the leaves are dispersed all 
round, and are more or less erect also. In both cases the object 
gained is to acquire the best possible directions to receive the incident 
light. The fastigiate form is characteristic of the Cypress, Lombardy 
Poplar, and many other trees, of which the original type has horizontal 
and spreading branches. In order to distribute the leaves horizontally two 
methods are adopted. In the common Laurel, for example, the leaves 
issue in two ranks (distichous) from the branch which extends horizon- 
tally ; but if a shoot appear on the upper part of the bush and grow up 
vertically, then the leaves will be in five ranks (pentastichous). In the 
