58 Abstracts 



Chapter 11 deals with the principles of a natural arrangement of the species 

 within the genus, and in Chapter III the importance of the different forms of 

 hairs is considered from both the taxonomic and ecological standpoints. Chapter IV 

 deals with seedling forms, those of six New Zealand members of the genus being 

 described at length. The occurrence of long, many-celled, thin-walled hairs in 

 certain early seedlings, but which are absent in the adults, is noted as requiring 

 special investigation. 



Chapter V deals with the plant-geography of the genus. The question as to 

 whether it is primarily subantarctic or the contrary is discussed, and. on the assump- 

 tion that certain characters are older than others, a pica is established for a northern 

 rather than a southern origin. But. on the other hand, it is shown how the pre- 

 sent extensive occurrence of species not only in subantarctic South America, but 

 throughout the subantarctic zone as a whole, together with New Zealand and pa its 

 of Australia, supports the theory of a southern origin. 



Certain cases of discontinuous distribution are cited, especially that of the 

 section Acrobyssinoideae, one species of which .4. tasmanica Bitter, is endemic in 

 Tasmania, but all the other species occur in the Chilian Andes from lat. 39'5° south 

 to Cape Horn and South Georgia. A. californica Bitter, endemic in California, 

 belongs to a section not otherwise extending north of central Chile and Patagonia. 



The occurrence of local forms is much commoner than has been thought hitherto, 

 especially on the isolated subantarctic islands. This discounts considerably the 

 general view that the supposed wide area of certain species was due to carriage 

 of the fruits with their hooked barbs by birds. At the same time, the author con- 

 siders the occurrence of closely related species in distant localities due to bird- 

 carriage, and cites a Sandwich Island species, with its close I'elatives in south and 

 central Chile, and the Acrobyssinoideae of the Magellan region and Tasmania, but 

 absent in New Zealand. But such distribution was not frequent enough to hinder 

 the evolution of many local forms. 



It is a remarkable fact that the New Zealand species of Acaena possess the 

 following peculiarities not present in members of the genus elsewhere : (1.) A 

 stunted habit of growth, although their foreign allies are robust and large-leaved — 

 as, e.g., the New Zealand forms of the polymorphic A. Sanguisorbae Vahl as com- 

 pared with the Australian, and the three new species formerly referred to A . 

 adscendens Vahl in New Zealand in comparison with the true species of that 

 name and A. laevigata (Ait.) Bitter of South America. Nor can the alpine climate 

 be responsible for the marked exhibition of this growth-form in the endemic New 

 Zealand section Microphyttae, since the Chilian Andean species show no such 

 character. (2.) The brownish colour of the leaves in certain varieties of the 

 Sanguisorbae group and in .4. microphylla Hook, f., and such colouring is present 

 in members of other families of New Zealand alpine plants. Grey-coloured leaves, 

 arising either through a covering of wax or through air-spaces between the cells, 

 is another characteristic, but there are Chilian examples of similar phenomena. 



It would serve no purpose to draw up a synopsis of the author's arrangement 

 of the New Zealand species. A really critical study of his work is demanded on 

 this point. Here only some general conclusions are noted regarding the limitations 

 of species, important alterations, and so on. 



First, it must be pointed out that a most comprehensive view is taken as to 

 the species themselves, so that the polymorphic species are groups which do not 

 exist at all as true entities. These species are subdivided into smaller but still 

 comprehensive groups as subspecies, these into varieties which are the true entities of 

 the flora, and these occasionally into forms. 



A subspecies of A. ovina A. Cunn. is created called nanella Bitter, based on 

 specimens sent by Cockayne to Berlin as introduced and collected on the Canter- 

 bury Plains, the author considering the stunted habit of specific importance. 



Acaena adscendens Vahl, hitherto supposed to extend to New Zealand, is 

 restricted to plants of the Magellan region and Kerguelenland, while the New Zea- 

 land forms referred to A. adscendens are treated by the author as three distinct 

 species — A. saccaticupula Bitter, A. hirsutula Bitter, and A. fissistipula Bitter, the 

 two latter being closely related, but the former coming into a different subsection 

 allied to that containing A. adscendens. Varieties are also described of all three 

 species. 



Acaena Sanguisorbae Vahl is restricted to Australian, Tasmanian, and New 

 Zealand plants, the Tristan d'Acunha plant being referred to A. sannrntosa Car- 

 inichael and considered as restricted to that group, while the New Amsterdam plant 

 is referred to A. insularis Citerne. 



