FOLIAGE OF CONIFEROUS PLANTS. 21 



bristle. In the Cypress and its allies they are dimorphous, the earliest 

 formed or "juvenile" leaves being linear, flattened, and frequently 

 falcate ; the mature or adult ones, scale-like, rounded, or pointed 

 at their apices. In Ginkgo the form of the leaves is unusual, 

 being broadly fan-shaped, with the edges jagged or much notched. 

 Many other forms occur in the Australian and other genera.* The 

 arrangement of the leaves is also much varied. In the true Pines 

 they are spirally set around the branches in bundles of twos, threes, 

 and fives, each bundle being enclosed at the base in a sheath composed 

 of membranous scales, which are deciduous in some species. f In the 

 Spruce Firs, Cryptomerias, Wellingtonia, and others, the leaves are 

 densely scattered over the branchlets, or spirally arranged around 

 them, and often pointing laterally in two directions. In most of 

 the Silver Firs, the Hemlock Firs, Taxodium, the Eed Wood, and 

 most of the Tew tribe, they are distichous (two rowed) or pectinate ; 

 in Cedrus and Larix, fasciculated ; iff many of the Junipers, in 

 whorls of three's ; in the Cypress tribe, generally closely imbricated 

 in four rows. The persistency of the leaves varies in the different 

 tribes; the Larch, Deciduous Cypress, Chinese Water Pine, and 

 Maiden-Hair Tree are deciduous; in some of the Pines the leaves 

 remain on the trees several years, and Araucaria imbricata retains 

 its foliage from ten to fifteen years. In all the tribes, with the 

 exception of the Maiden-Hair Tree (Ginkgo), the leaves are entire 

 at their edges, but in Pinus the edges are frequently rough, with 

 serrations invisible to the naked eye ; the veins are parallel ; and 

 the stomata, when present, are regularly arranged in rows, some- 

 times interrupted, and in many species found on the upper as well 

 as on the under surface. 



The colour of the foliage is not less Varied than the forms of the 

 leaves. From the deep sombre hues of the Austrian Pine and 

 Common Yew to the light and airy deciduous Cypress and Maiden- 

 Hair Tree, the silvery lines of the "Weymouth Pine, and the greyish 

 foliage of Retinospora squamosa, there is found in the different tribes 

 an endless Variety of tints which the green of Nature alone displays. 



* Among these Phyllocladus is remarkable for having "leaves of two forms, some 

 minute and scale-like, others linear, seen only in young plants, hut which m older are 

 Connate into flat fan-shaped organs (phyllodes), resembling simple leaves, which hear the 

 inflorescence at their edges."— Sir J. D. Hooker, New Zealand Flora, p. 259. 



f These scales are, hy some botanists, regarded as imperfect leaves, from the axils of 

 which the true leaves arise. 



