Jay. 1911.] | BOTANICAL SOCIETY OF EDINBURGH 113 
4. GROWTH-FORMS, 
(@) GENERAL, 
In order to understand the all-important relations of 
the plants to one another a knowledge of their growth-forms 
is essential, since on their humus-making capacities, power 
of affording shelter, germination facility, vegetative increase, 
root-systems, xerophytic structure, and so on, depends 
almost entirely the sequence of events. In other words, 
though the first colonists are those fortuitously brought 
by various agencies from the comparatively rich flora of 
the neighbourhood, only those suited to the severe ecological 
conditions can gain a footing in the first place; but after- 
wards it is the growth-forms of the plant-colonists them- 
selves which finally, or at anyrate equally with soil and 
climate, determine the character of the associations and 
the procession of events. 
(b) SYNOPSIS OF SPECIES ACCORDING TO THEIR 
GROWTH-FORMS. 
A.—Low Trees. 
(a) Summergreen. 
Gaya Lyallii) (Hook. f.), J. E. Baker (branches slender, 
somewhat fastigiate; leaves bright-green, not thick). 
(b) Evergreen. 
Phyllocladus alpinus (2), Hook. f. (trunk slender; 
cladodes thick, coriaceous). 
B.—Shrubs. 
(a) Leafless (more or less). 
* Summergreen or partly so. 
(1) Shoots frequently reduced to spines. 
Discaria towmatow, Raoul. (erect, 60 em.—4°5 m. tall; 
branches numerous, divaricating; leaves small ; young 
stems and spines green; roots long). 
(2) Shoot-axes green, assimilating organs. 
Carmichaelia grandiflora, Hook. f. (erect or decumbent, 
1 Also shrubs, 
