The Growth-Forms of Netted FJaiits. 
613 
this great variability in the same species, as will be illustrated throughout 
this paper, is one of the most striking features of Natal vegetation, and it 
cannot be too much emphasised. It is due, doubtless, in the first instance, 
to the very great range of differences in the natural conditions, and it proves 
also that the native plants of Natal possess great plasticity, in that single 
species are thus able to adapt themselves to very distinct environments. 
The total number of Mesophanerophytes is ch\ 420. The main features 
to be noted of this group are : 
(1) Proportion of Lianes. — Over 30 per cent, of the Mesophanerophytes 
of Natal are climbers. Certain large genera, such as Vitis and Ijjomaea, with 
sixteen species in each, help to swell the number. A notable feature is the 
number of shrubby species, which, in the absence of support, grow erect and 
may even form small trees, yet under suitable conditions become scandent. 
Almost every known variety of liane is found (except root-climbers). 
Some are simple scramblers, with the usual elongated type of stem, but 
with none of their organs specially modified for climbing ; others possess 
various kinds of tendrils. Many are spiny. Some are semi-herbaceous 
perennials — the annuals are, of course, not included here — but the majority 
are of a woody type. 
The watch-spring tendrils of the woody Dalbergias, etc., are well known. 
The various stout lianes of the forest are ]3opularly known as " Monkey 
Eopes." They form dense festoons and masses, and make it somewhat 
difficult to penetrate through the bush. They are particularly abundant in 
the Sand-dune Bush of the coast, in which there is little other undergrowth. 
From the economic standpoint, those " monkey ropes " must be ranked as 
the most pernicious weeds of the forest, since they often smother and kill the 
trees over which they climb. Their presence in such abundance alters the 
ecological character of the bush as a whole. They fill in the gaps, so that 
very little light penetrates, and the undergrowth of shrubs and herbs is very 
scanty, being confined more or less to the margin of the bush. The lianes 
also influence the regrowth of the forest. In the denser shade produced by 
them, the seedlings of light-demanding trees are killed, so that these also 
are confined to the outside margin of the bush. 
An increase in the number of lianes, therefore, leads to a decrease in the 
number of Nanophanerophytes and Chamaephytes, etc., inside the bush, and 
the lianes also modify the growth-forms and influence the distribution of the 
Mesophanerophytes. No better instance could be found of the vegetation 
itself as a factor influencing the vegetation. The dependence of the lianes 
themselves on the phanerophytes (trees) over which they climb is, of course, 
still more obvious. 
(2) Yariation m the G-rowth-forms of the separate Species. — 
This follows more or less the same lines as the Mesophanerophytes. The 
great plasticity of certain species is again noticeable. The size, amount of 
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