56 Abstracts 



A yellow-flowered form of Pittosporum tenuifolium has appeared at Berkeley, 



growing in a row of normal black-flowered plants. This form is unknown in ^sew 



Zealand, but according to Oheeseman yellow-flowered forms are known in other 



dark-flowered species. „ 



Li. L/. 



4. Die Geographie der Fame. By H. Christ. Pp. ;b r >7, figs. 130 (mostly 

 from original photographs), and 3 maps. Gustav Fischer. 

 Leipzig; 1910. 



This work, from the hand of a. most eminent pteridologist, is obviously of 

 special interest to New Zealand biologists. It is divided into a general introduc- 

 tion and two parts, the first (pp. 0-136) being ecological, and the second (pp. 139-333) 

 floristic. There is also a bibliography, which does not aim at completeness, of 18V 

 titles arranged according to the various fern floras and their divisions, together with 

 those dealing with general plant-geography, general works on ferns, and studies 

 on special ferns and groups. The illustrations show both individual plants and 

 fern-associations. Fig. 124, entitled Leptopteris superba, taken by Cockayne, is 

 really Polystichum vest it am, and the locality is not Stewart Island, but forest at 

 hase of Big Ben, Canterbury. 



In the introduction it is pointed out that the general impression that ferns. 

 through ease of distribution by their spores, are more readily spread than flowering- 

 plants, and have a wider distribution, is not the case. Thirty years' study of fern 

 material from all over the globe has convinced the author that, in general, the dis 

 tribution of ferns goes parallel with that of phanerogams. Where endemism is 

 strong for the latter, so too is it with the accompanying ferns. 



The ecological section is brimful of interest for New Zealand botanists, and 

 requires close attention; a brief summary would be of no value. Many New Zea- 

 land species and genera are mentioned, while the ferns of other regions frequent 1\ 

 exhibit parallel structure. Ferns, as a whole, are considered mesothermous hygro- 

 phytes and xerophytes. 



Part II, dealing with fern floras, concerns students of bio-geography in general. 

 Certain fundamental principles and matters are first explained — e.g., endemism, 

 which may be recent or ancient, as in the case of the New Zealand Loxsoma, with its 

 sole relatives two species of Loxsomopsis of Central and South America; numerical 

 '.elation of ferns to seed-plants in the different floral regions, and amongst other 

 details it is shown that out of the 149 genera of ferns only thirty-three do not occur 

 in the tropical forest-region, and of these Doodia, Loxsoma, Leptopteris, and Toden 

 are confined to the South Temperate Zone; the fern-areas, which are, on the whole, 

 more extensive than those of phanerogams, but yet a similar local endemism occurs 

 in both classes ; the cosmopolitan ferns, of which there are twelve well-defined 

 (though it may be polymorphic) species, which occur with a few trifling exceptions 

 over the whole globe*; pantropic ferns; the northern circumpolar extension of 

 terns, the author being of opinion that a backward current of species is moving 

 northwards from a Tertiary haven of refuge for the forest-ferns in South Chinn. 

 the basal Himalayas, and Mexico ; the arctic-alpine element, together with relics 

 from the glacial period, but these are much fewer than are the flowering-plants 

 of that character ; and, finally, discontinuous areas of distribution, of which the 

 following examples concern New Zealand : Blechnum Fraseri (New Zealand and 

 Philippines), B. Patersoni, Gleichenia dicarpa, and other ferns of the Australasian 

 flora, which, in common with the phanerogams, Spinifex, Melaleuca, and Casuarina. 

 extend to the mountains or the strand of Malaya, and Todea barbara of New Zea 

 land, Australia, and South Africa. 



The distribution of certain genera is considered in detail : that of Ophioglossum , 

 Botrychium, and Gleichenia alone concerns New Zealand. The forms of Ophio- 

 glo8sum are ill equipped for wide distribution, since they spread rather by a feeble 

 vegetative increase than by their scanty spores. Their universal but quite local 

 occurrence — for they are frequently isolated by wide tracts — together with their 

 small amount of variation, is. according to the author, the greatest puzzle in the 

 geography of ferns. In the far south of Australia and New Zealand, and in 

 Argentina, South Chile, and Patagonia, the little northern species Botrychium 

 lunaria occurs — an arctic footstep in the snbantarctic ! Between Ophioglossum and 

 Botrychium s fundamental distinction exists, the former being tropical-cosmopolitan. 



* The following are absent in}N>w Zealand: Adumtum capillus ven«ri$, ! Pt-erix cretico. Dryopleri? 

 lilixmiK. Oxmunia regali*. 



