22 FOLIATION. 



character, however, is no more absolute than any other, for in P. 

 monfana while the central shoot is leafy at the base, the lateral shoots 

 from the same cluster of buds are naked at the base. 



The species of Cedrus, Larix, Laricopsis (Pseudolarix) and Ginkgo 

 are remarkable for the production of two kinds of branches, the one 

 long and slender with the leaves distributed at intervals, the others 

 short and thick with the leaves in tufts at the extremities.*. The 

 former are the extension or leader shoots in which growth and develop- 

 ment are rapid ; the latter are analogous to similar growths in the 

 Apple, Pear, Laburnum, but are in the TAXACEJK and COXIFEFLE not 

 ' necessarily connected with the production of fruit, although in Cedrus 

 and Laricopsis (Pseudolarix) the spurs bear the staminate flowers, and 

 in Ginkgo both the staminate flowers and the fruits are produced from 

 the apex of the spurs. The leaves on the extension or leader shoots of 

 Cedrus and Larix are generally longer and more glaucous than those 

 on the spurs, and are stomatiferous on both sides. 



The mode of development of the spurs may readily be traced in 

 the Larch and Cedar, and confirm the view that the appearances are 

 due to the more vigorous growth of the basal and peripheral parts in 

 comparison with the central and apical portions. Thus, if a bud at 

 the end of a shoot be examined in October, the apex will he found 

 to be dome-shaped ; the young leaves emerge in succession from the 

 base of the dome, leaving the apex naked, so that the development 

 of the leaves is centripetal. If one of the lateral buds be examined 

 at the same time, the axis will be found to form, not a dome, but 

 a cup from whose margins the leaves protrude, those at the upper 

 edge of the cup being the . oldest and corresponding . to those at the 

 base of the dome. These lateral buds are those destined to form the 

 tufts of leaves on the spur; the greatest energy of growth is in the 

 one case at the apex of the growing axis, in the other at the base 

 of it. 



FOLIATION. 



THE term is here restricted to foliage leaves only, and to 

 organs that function as such, as the phylloid shoots of Seiadopitys 

 and the cladodes of Phyllocladus. The morphology of the leaves in 

 the cotyledonary state has been already noticed. 



The cotyledonary leaves are almost always followed by leaves that 

 differ in form and arrangement both from the cotyledons and from 

 the adult leaves of the same species ; they are known as primordial 

 or protomorphic leaves. Except in Ginkgo, they are linear in shape, 

 and are either spirally arranged around the axis (Pinus, Abies, 

 Picea, etc.) ; scattered (Cedrus, Larix, Sequoia, Taxus, etc.) ; or in 

 decussate pairs (Cupressus, Thuia, Libocedrus, etc.) Sometimes they 

 are separated by a distinguishable interval, but there are cases in 

 which they are so crowded as to appear tufted ; there are also 

 cases in which they are seen to pass gradually into the adult state, 

 These primordial leaves can be readily recognised in most species ; in 



* In reality the leaves are arranged in a spiral as on the longer shoots, but thfv arc so 

 closely packed that the spiral arrangement is often very much obscured. 



