The Growth-Forms of Natal Plants. 
629 
HYDEOPHYTES. 
These are the purely aquatic forms, and they are included by Raunkiaer 
with the Helophytes, the two together forming the class H.H. In Natal, 
Hydrophytes are scarce. There are no lakes of any size, owing to the steep 
rise of the land from the sea to the Drakensberg. In the dry winter season, 
in most districts, there are few pools of water even. The Hydrophytes, 
therefore, are mainly stream plants, but they are nowhere abundant. 
The total number of Hydrophytes is 25. The total number of Helo- 
hydrophytes (Class H.H.) is cir. 168. 
Eaunkiaer gives 1 per cent, as the normal amount of H.H. This number 
seems to the writer to be too low. At any rate, in Natal it is at least five 
times that amount^ — 5 per cent. 
This higher proportion of marsh plants might be taken to indicate that 
much of the land in Natal is marshy. This is not the case. Yleis are 
exceedingly numerous, but not, as a rule, very large. The arrangement of 
successive terrace plateaux, with the rivers eating their way back through 
them, and with the general rate of denudation exceedingly rapid, leads to a 
network of small streams. These, wherever the ground is more or less fiat, 
spread themselves out and form vleis. Consequently we have vleis at all 
altitudes and under every different kind of external condition known in 
Natal. Though, in spite of this, there is more uniformity in the vlei vegeta- 
tion than in any other plant formation in Natal, yet the total number of vlei 
species (Helophytes) is greater than if the same total area of vlei had been 
confined, say, to the lowlying coast lands. 
The high proportion of Helophytes therefore does not mean that a large 
proportion of the total area is marsh, but that there is a greater diversity 
than usual in the types of marsh. 
THEEOPHYTES. 
These are the plants of the favourable season, the annuals. Intemperate 
regions, Aestival or Summer Annuals, and Hibernal or Winter Annuals are 
distinguished. In Natal this distinction is not necessary, since they are all 
summer annuals. The vegetative period varies from one to several months. 
Therophytes are not numerous in Natal, the percentage being only one-half 
that of Eaunkiaer' s normal spectrum. A high percentage of Therophytes is 
characteristic — (1) of desert regions, particularly regions with dry, hot 
summers ; and (2) of localities where the soil is regularly and periodically 
disturbed (cultivated land, sea-shore, sand, etc.). The Natal Therophytes 
belong mostly to the latter class, being the weeds of cultivated land. Many 
of them are exotic or doubtfully native of Natal. 
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