Page:Manual of the New Zealand Flora.djvu/532

492 Students using the conspectus should bear in mind that the characters employed are in many cases arbitrary ones selected to show how the dominant forms of a certain species differ from those of another species, and do not always include the entire range of variation of a species. Plants like V. salicifolia, macrocarpa, parviflora, Traversii, buxifolia, pinguifolia, &c., which run into numberless varieties, are probably quite incapable of rigid definition.

It should be mentioned that several species from the Northern Hemisphere have become naturalised in New Zealand, the most abundant being V. serpyllifolia, V. arvensis, V. agrestis, and V. persica. Descriptions of these will be found in any British Flora.

A. Leaves quite entire (sometimes minutely incised in V. salicifolia, amabilis, diosmœfolia, Colensoi, and others; occasionally toothed in V. Haastii).