188 CONIFERS. 



says : J " I must here observe a remarkable peculiarity belonging to 

 the Conifer of the Southern Hemisphere, which is, that while the 

 trees are young their leaves are long and divaricating, but when 

 they become old enough to bear fruit, those leaves fall off, and are 

 succeeded by short scales, closely imbricated on the branches, so 

 that, seeing them in their different states, one could hardly suppose 

 it possible that they could belong to the same species." This 

 young form of leaf may be retained for some few years before the 

 adult foliage is developed, and thus present a possible source of 

 error in the determination of fossil branches. In such a species as 

 Pinus pinea, L., we have the young leaves retained for some con- 

 siderable time previous to the development of the needles and short 

 shoots. An interesting case of this difference between the leaves 

 of young and adult plants was pointed out to me at the Royal 

 Gardens, Kew : the young plants of the new species of Widdring- 

 tonia, W. WJiytei, Rend., 2 from Nyassa-Land, bear comparatively 

 long needles, in marked contrast to the small scale leaves of the 

 older tree. A striking instance of a similar kind is afforded by 

 some specimens of Araucaria excelsa, R. Br., in the Herbarium of 

 the British Museum : there is a seedling with its long and spreading 

 leaves, an older specimen with narrow and spreading leaves, and 

 another with the stiff leaves of the adult plant. In Dacrydium 

 Kirkii, F. Muell., 3 from New Zealand, we find a marked difference 

 between the small and closely adpressed leaves, and the much 

 larger and more spreading leaves of other branches ; also, in 

 D. elatitm, Wall., D. Westlandicum, Kirk., 4 and other forms, there 

 is a striking disparity in the leaf form. In Podocarpus cupressina, 5 

 R. Br., there is a decided difference between the young and old 

 forms of leaves. In Athrotaxis selaginoides, Don., 6 we have various 

 forms of leaf, from the longer and more openly disposed to the 

 smaller and closer leaves. Among other species exhibiting similar 

 differences in the shape and size of the leaves, we may note the 

 well-known Juniperus Chmensis, L., Biota orientals, EndL, Juni- 

 perus Bermudiana, L., Glyptostrolus heterophyllus, End!., etc. 



1 Lambert, p. 89. 



2 Eendle, p. 60. 



3 Hooker (1), pi. Mccxix. 



4 Ibid. pi. Mccxviii. 



6 Brown and Bennett, pi. x. 

 6 Don, pi. xiv. 



