128 
F. E. Fritsch and E. J. Salisbury. 
part monopodial. Probably correlated with the dense character of 
the periphery, the interior of these aerial cushions exhibits an early 
dying away of the lateral appendages, so that only the outer parts 
appear green. 
In marked contrast to the wind-trimmed shoots are such as 
grow in the shade and shelter afforded by other plants or branches 
(shade-type, cf. below). The chief features of these are their flexi¬ 
bility and the slender nature of all the appendages. In concluding 
our consideration of the growth-forms of Ulex attention may be 
called to the fact that all the different types may occur together on 
different parts of the same plant, where these are differently circum¬ 
stanced. We may therefore distinguish the following types:—(1) 
the prostrate type, rarely observed in U. europceus ; (2) the inter¬ 
mediate type, with both prostrate and upright branches (3, p. 152), 
only observed in U. nanus ; (3) the erect non-exposed type ; (4) the 
aerial cushion type; (5) the corymbose type, only observed in U. 
nanus ; (6) the shade-type. 
(3) Growth-forms on the Land-slides. 
Some of the most striking growth-forms are to be found on the 
hare areas left by land-slides on the N.W. slopes of valley B (see 
Fig. 1), hut these appear to he due to the combined action of wind 
and rabbits. Perhaps it may be well to mention at this point that 
the growth-forms enumerated in the preceding section are due 
entirely to exposure, the actual dead tips resulting from this influence 
having been observed in numerous instances; moreover, in the case 
of the aerial cushions their height above the ground precludes the 
agency of rabbits. Over most of the area the grasses and sedges 
alone appear to he attacked by these animals, hut near their burrows 
which are mainly situated in the land-slides nearly all the species 
present seem to he nibbled. This is apparently not done for the 
sake of food, since the detached tips are often found scattered 
around. Although the areas under consideration are situated on 
the sides of a valley, this runs in the direction of the prevailing 
winds, and further, owing to the open character of the association, 
little shelter is afforded, so that wind probably plays a considerable 
part in the production of the growth-forms now to be discussed. 
Ulex europceus , U . nanus, Calluna and Erica cinerea all exhibit 
cushion or mat-like forms appearing as extreme examples of the 
type found on burnt areas. It is of interest to note that these 
cushions of U. nanus have been observed producing numerous 
