218 PROCEEDINGS OF SECTION D. 



botanist unacquainted with tlie " normal " plant. Further, sucli 

 a plant might very well become, as Diels has suggested,^ the starting 

 point of a new line of descent. 



A striking shrubby growth-form, which is extremely common 

 in many parts of New Zealand, is the divaricating. It is distin- 

 guished by the very frequent branching at almost a right angle, 

 so that a close, entangled, usually stiff twiggy growth results. It 

 occurs in various families (e.g. — Pittosporacece, Riitacece, Icacinacece, 

 RhamnacecB, Elaeocarpacece, Violacece, AraliacecB, CornacecE, Myr- 

 sinacecB, Rubiacece, CompositcB), and in genera which may also 

 exhibit altogether different growth-forms. But, especially im- 

 portant from the standpoint of this paper is the fact that the 

 divaricating-form affords a most excellent example of convergent 

 epharmony, various members, generically distinct, not only looking 

 exactly alike, but growing associated together in certain xerophy tic 

 montane and subalpine stations. Now this growth-form is not 

 merely confined to shrubs, but is an early stage in the development 

 of certain trees, which are thus xerophytic shrubs for sometimes 

 several years and afterwards mesophytic trees. The following are 

 trees of this class : — Hoheria angiistifolia, H. sexstylosa, Plagianthus 

 Z)^^w/m«s (Malvacaceae) ; Pennanliacorymbosa (Icacinaceae) ; Sophora 

 microphylla (Leguminosae). So far as the above s\)e.c\esoiMalvacecB 

 go, I have neverseen actual juvenile shoots blooming, hut Plagianthus 

 divaricatus, a well-marked halophytic species, is always a shrub. 

 Pennantia corymbosa has occasionally flowering juvenile shoots, but 

 these occur on the persistent shrubby form still at the base of an 

 adult tree. So, too, with Sophora microphylla, but in this case there 

 is the variety prosfrata, which comes true from seed, is confined to 

 xerophytic stations, blooms freely, does not grow into a tree,- and 

 is, most certainly, the fixed juvenile form of 5. microphylla, though 

 its flowers are smaller and its pods slightly different from those of 

 that species. 



The shrub-stage of the above trees, S. microphylla excepted, 

 might well be considered non-epharmonic, and its origin bound up 

 in the phylogeny of the species, as indeed it probably is, to some 

 extent. But, on the other hand, the earliest seedling state is not 

 xerophytic, and the succeeding shrub-stage may well be an advan- 

 tageous growth-form for a plant of dry soil, or wind-swept station, 

 in its early years. Afterwards, as a mesophytic tree, and a member 

 of a forest, it would better cope with the quite different environment. 



In the case of Sophora prostrata, a plant of a xerophytic station, 

 an ontogenetic origin may perhaps be assumed, the habitat favour- 

 ing the shrub-rather than the tree-form. At the present time, in 

 certain stations, shrub and tree grow side by side as might be 

 expected were the above supposition true, but in the most xero- 

 phytic stations S. prostrata alone is present. In the case of the 

 other trees cited, their present habitats do not justify the theory of 



1. Loc. cit., p. 109. 



2. Wind-swept examples of 5. microphylla must not be confused with this plant. 



