( 169 ) 



IX. 



GINEQOPHYLLUM KILT0RKEN8E sp. nov. 



By T. JOHNSON, D.Sc, F.L.S., 

 Professor of Botany in the Royal College of Science for Ireland, Dublin. 



(Plates X-XII.) 



[Read Noyemrer 25, 1913. Published February 27, 1914.] 



The discovery in the year 1896 by Hirase of the occurrence (1) of ciliated 

 aiitherozoids in Ginkgo bi/oba,^ the Maiden-hair tree or Sa/isburia adiantifolia, 

 justified more than ever the separation of this genus from the re.st of the 

 Couiferae with their aerial mode of fertilization by non-motile male nuclei, 

 and the institution, for its inclusion, of the group of Ginkgophyta or Gink- 

 goacese. It added interest also to the attempt to trace backwards in time 

 through the rocks the first signs of the emergence of the group in the flora 

 of the world. 



To Hear (2) belongs the honour of proving that the representatives of 

 Ginkgo show the characteristic foliage and reproductive organs. 



The group reached its zenith in the mid-Jui'assic period in such a form as 

 Baiera. Some twenty species, found in nearly all parts of the world, even to 

 79' N., are on record for this epoch. 



Though the presence of Ginkgoacese throughout the Tertiary and 

 Mesozoic rocks is generally admitted, the ease is different on descending 

 to the Palaeozoic rocks. There is not on record under any generic name 

 anything more complete than leaves or foliage shoots suggestive of a 



' The most recent arboriciiltural account of Ginkgo biloba is given in the " Trees of Great Britain 

 and Ireland" by Elwes and Henry, vol. i, pp. 52-62, pis. 21-23, 1906. I have it on the 

 authority of my colleague. Professor Henry, that, statements to the contrary notwithstanding, there 

 is no reliable evidence that Ginkgo is indigenous in any part of China. It owes its survival in 

 this case to the commendable habit of the people of China and Japan of planting it in groves round 

 their temples from time immemorial. J. S. Gardner (Monograph of the British Eocene Flora, 

 J. Starkie Gardner and C. von Ettingshausen, Palseont. Soc, 1886, p. 100) describes the Ginkgo he 

 found in the Tertiary basalt at Ardtun in the Isle of Mull as specifically identical with Ginkgo 

 bUoba, though in the Palteontographical Society's Memoir he describes the specimens as G. adiantoides. 

 J. S. Gardner's naming is, he states, in accordance with custom, which requires a different specific 

 name for an Eocene form even though identical with a living species. 



SOIENT. PROC. R.D.S., VOL. XIV., NO. IX. 2 



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