Cockayne. — Ecological Studies in Evolution. 41 



a plant I considered R. Traversii, but which Cheeseman is of opinion is 

 either a hybrid* on a new species, grow together on the Snowcup Moun- 

 tains, Canterbury. Ranunculus Buchanani Hook. f. and the closely related 

 R. Matthewsii Cheesem. grow in company on certain alpine herb- or fell- 

 fields of western Otago. Anisotome pilifera Cockayne and Laing and its 

 var. pinnatifidum T. Kirk grow in company on peat-covered rocks, &c, 

 in the Southern Alps. Leptospermum ericoides A. Rich, and L. lineatum 

 Cockayne grow together on northern dunes. Coriaria angustissima Hook, f., 

 C. thymifolia Hunt. & Bonpl., and C. ruscifolia L. grow in proximity on 

 Westland river-beds. Aciphylla Colensoi Hook. f. var. conspicua T. Kirk 

 and the var. maxima grow near one another on certain herb-fields or in 

 scrub on the Southern Alps. Two forms of Ourisia sessiliflora Hook, f., 

 the one densely villous and with large flowers, f the other a smaller plant 

 in all its parts, the leaves darker green and less hairy and the flowers 

 fewer and smaller, occur on the same herb-field in the Southern Alps. 

 Pittosporum rigidum Hook. f. and P. divaricatum Cockayne (see Plate I) 

 occur in the same forest-area on the volcanic plateau. Sophora micro- 

 phylla Ait. and S. prostrata Buchanan grow side by side in the bed 

 of the River Waimakariri at the lower gorge. Doubtless a number of 

 other examples could be found. The coupled plants are in all cases so 

 closely related that they are considered by most New Zealand botanists 

 either varieties of one species, the type and a variety, or forms not worthy 

 of or that have not yet received a name. They are quite sufficient in 

 number to show that it is not unusual for closely related hereditary plant 

 entities to exist side by side for considerable periods. 



The occurrence of distinct races of the same species at different points 

 of its area of distribution is known in a few cases. As Leavitt says, such 

 cases do not look like the work of mutation, nor can they be readily corre- 

 lated with epharmony. The following are two striking examples : Rubus 

 australis Forst. f. is a common plant both in forests and the open through- 

 out the North, South, and Stewart Islands. In the northern part of the 

 North Island it has, as a rule, much narrower leaves than in the southern 

 part of its range— so much so that typical plants from the two areas 

 have a very different appearance. The primary seedling-leaves seem to be 

 identical in both forms : these are ovate or ovate-lanceolate, and coarsely 

 toothed ; they are soon succeeded by narrow leaves, much resembling 

 those of R. parvus Buchanan, even as to their yellowish or slightlv brownish 

 marking. Seedlings growing in the forest-shade, and only 25-5 cm. tall, 

 bear these narrow juvenile leaves, thus showing the form to be inherited, 

 and not merely an epharmonic sun form. Since heredity is undoubted, 

 the northern form demands a name. Styphelia fasciculata (Forst. f.), a 

 heath-like small or tall shrub, extends from the North Cape to Canterbury 

 and Westland. The adult form varies but little throughout its range, 

 but the juvenile of the Auckland district has altogether broader leaves 

 than that of the south. An example of a more local character is that of 

 the mountain-herb Celmisia coriacea Hook, f., which from Mount Mau- 

 ngatua and other mountains in that part of Otago can be distinguished 

 at a glance as a cultivated plant from other specimens collected on the 



* The occurrence of this plant on Walker's Pass far from R. Monroi Hook. f. 

 removes the suspicion of a hybrid origin, which Cheeseman adopted, partly at my own 

 suggestion in the first instance. 



f To this plant I gave the MS. name of 0. splendida some year.s ago. 



