New Zealand Plants and their Story
From the subantarctic islands to the subtropical Kermadecs is a long step, and, yet the dominant tree in the latter is also a Metrosideros (M. villosa), a relation, however, of the pohutukawa and not of the southern rata. But with this the similarity between the two regions ends, except that both are of volcanic origin; and there is no more outward resemblance between the plant-forms than there is between the climates.
As seen from the sea, there is nothing in the appearance of the plant-covering of the Kermadecs to recall the tropics. No feathery cocoanut-palms fringe the shore. On the contrary, the rather dull hue of the New Zealand foliage, as seen from a distance, is everywhere manifest.
Sunday Island, the largest of the group, is forest-clad, while Macauley Island is almost entirely without arborescent growth. The whole group is of volcanic origin, as stated above, and the small Curtis Island is still in the solfatara state.
A certain number of tropical plants have reached the Kermadecs, but nothing like what might be expected. Amongst these are Ipomaea pes-caprae (which forms the well-known plant society on so many tropical shores), Canavalia obtusifolia (a climbing leguminous plant), Ageratum conyxioides (which bears the name of cherry-pie, or wild heliotrope), Aleurites moluccana* (the candlenut of the Polynesian Islands), and also some grasses and one or two ferns.
Certain plants are peculiar to the group. Amongst these are two coprosmas, C. petiolata and C. acutifolia, the former closely related to C. chathamica, of Chatham Island; Suttonia kermadecensis, related to a Norfolk Island plant; Homalanthus polyandrus, a tree of the spurge family; and two fine tree-ferns, Cyathea Milnei and one discovered by Oliver and named by him C. kermadecensis.
But the rank and file of the plants are such as would be met with in the North Island—for example, the karaka, ngaio, wharangi (Melicope ternata), mahoe, tutu, ivy-tree (Nothopanax arboreum), &c. In fact, about four-fifths of the flora † consists of ordinary New Zealand plants.
* According to Oliver this is not indigenous.
† According to Oliver there are 114 species, which belong to 88 genera and 42 families.