258 . The Vegetation of the Chatham Islands. 
3. The Biology of the Plants. 
a. Trees. 
Trees number 21; their growth-forms are: — Tuft-tree 6 (palm ı, ferns 5); 
canopy-tree 7; bushy-tree 6; tree-composite ı; araliad ı. All are usually low 
but’ at times a few may reach a stature of ı5 m or more but as a rule they 
vary from 6—ı3 m according to situation. Several readily assume the shrub- 
form especially Suitonia chathamica and Olearia Traversü. Dracophyllum 
arboreum is not of the usual fastigiate habit of its congeners and is here included 
amongst the canopy-trees. 
Generally, the tree-crowns are denser than those of the same species of 
the mainland and resemble those of coastal trees. The trunks are slender and 
straight. The appearance of Verenica and Coprosma, as true forest-trees, must 
be specially noted. /n species or genera strongly heteromorphic in New Zealand 
proper the phenomenon is exhibited to a very trifling extent, e. g. — the juvenile 
forms of Plagianthus betulinus and Sophora just hint at the divaricating form. 
So too with Pseudopanaxr chathamicum, the juvenile stage has leaves of an 
adult type, but it nevertheless persists sometime with straight unbranched 
stem. Dracophyllum arboreum has broad spreading leaves as juvenile after the 
manner of but not nearly so broad or large as D. Zatifolium but absolutely 
distinct from ‚the narrow grass-like leaves of the adult. They appear on 
reversion-shoots in the crown of the tree and this stage may blossom. The 
juvenile Coprosma chathamica has much more mesophytic leaves than the adult 
and they are frequently much larger. The heterophyliy etc. of V. gigantea 
has been already described. 
Coming now to the leaves; those of 20 are broad (simple 13, compound 7) 
and of ı grass-like; 19 have glabrous leaves, 2 hairy (1 tomentose); ı2 thin 
and 9 coriaceous or thick. Their dimensions are: very large (20 cm and 
upwards in length) 6; large (10—20 cm long) 3; medium (5—1o cm) 4; small 
(2.5—5 cm) 8. All are wegen excepting P. betulinus var. chathamicus and 
perhaps the Sophora. 
The flowers of 5 species are more or less showy, g have succulent fruits 
and those of 2 specially suitable for wind-carriage. 
B. Shrubs lianes and epiphytes. 
Shrubs number 21 including the bamboo like Sporodanthus T; yaversü; the : 
remainder belong to the following growth-forms: — Bushy-shrub 9; divari 
cating 4 (1 spinous); composite-shrub 2; semi-ball-like r: straggling 2; Die 
ö Phyllum-form ı, prostrate 1. So far as individuals go the ehrub-compocl 
and Dracophyllum-forms are of prime physiognomic importance and specially 
‚rellect the prevailing climatic-edaphic conditions. 
ıe species have simple leaves; their characteristics and the number Ä 
of species possessing such are as E. Medium-sized 8; small 4; very 
small (less than 2.5 cm long) 8; thin. 5; coriaceous or thick 16; ner Be 
: hairy 4 el 3 re is  lcafless. 
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