﻿BOTANICAL GAZETTE 



Pearson? has been studying the morphology of Gnetum, and has recorded 

 some interesting observations. He finds four types of strobili in G. Gnemon, 

 which constitute a sequence from the strictly monosporangiate to the bispo- 

 rangiate condition. He also finds that the endosperm develops in many details 

 as that of Welwitschia, especially in the multinucleate character of the primitive 

 tissue. The nuclei in each "compartment" in the chalazal region fuse; while 

 in the micropylar region there is no septation. It seems, therefore, that the 

 primary endosperm of the two genera is alike in all respects. Pearson sees 

 in this endosperm a new structure which is neither sporophyte nor gametophyte, 

 but which he designates as "trophophyte," and it is further suggested that the 

 endosperm of angiosperms is a highly specialized form of this trophophyte. 

 The interesting suggestion is made that the fusing polar nuclei of angiosperms 

 may be morphologically the representatives of the fusing nuclei of Welwitschia 

 and Gnetum. 



Boodle 8 has discovered concrescent leaves on a tree of Pinus Laricio 

 growing in the Royal Botanical Gardens, Kew. These leaves are produced 

 every year in considerable numbers. It is suggested that the double needles 

 of Sciadopitys may be morphologically similar to those of P. Laricio, that is, 

 they may represent two foliage leaves fused by their margins. The orientation 

 of the leaves of the double needles of the Austrian pine, however, is not constant, 

 cases being found with fusion by the adaxial margins, by the abaxial margins, 

 and by obliquely placed leaves. — J. M. C. 



Endemic flora of Ceylon— In connection with the revision of his catalogue 

 of the Ceylon flora, Willis 9 has reached some interesting conclusions in refer- 

 ence to geographical distribution and evolution. The conclusions are derived 

 from the use of statistical methods and the classification of the Ceylon species 

 into a series of six groups, graded from "very rare" to "very common." He 

 observes that the rarest plants are local endemics, and the commonest are those 

 of widest distribution. The conclusion is that "local endemic species have not 

 been developed in any kind of advantageous response to local conditions." 

 That the endemic genera should show greater rarity than do the endemic 

 species as a whole cannot be explained by any such theory of adaptation. 

 Graphically Willis' observations would "run in the exact reverse direction all 

 through to that demanded by the theory of natural selection." A second 

 conclusion is that on the average the commonness of the species depends upon 

 its age locally, species developing "quite indifferently to local conditions, 

 though possibly because of those conditions." 



i Pearson, H. H. W., Notes on the morphology of certain structures concerned 

 in reproduction in the genus Gnetum. Jour. Linn. Soc. 43:55-56. 1915. 



8 Boodle, L. A., Concrescent and solitary foliage leaves in Pinus. New Phytol. 

 14:19-22.^.4. 1915. 



» Willis, J. C, The endemic flora of Ceylon, with reference to geographical dis- 

 tribution and evolution in general. Phil. Trans. Roy. Soc. London B 206:307-342. 



