510 PHANEROGAMS. 



four orders of shoots are developed in one plane in such a manner that a system 

 of this kind assumes a definite contour and somewhat the appearance of a pinnate 

 leaf. In Taxodium the foliage-leaves are formed in two rows on slender branches 

 a few inches in length ; in T. dislichum these fall off in the autumn together with 

 their leaves, thus presenting a still greater resemblance to pinnate leaves. Finally 

 Phyllocladus produces on all its verticillate shoots only small colourless scale-like 

 leaves, from the axils of which, but beneath the terminal bud, whorls of shoots spring 

 with limited power of growth, developing their bilateral side-shoots in the form of 

 flat-lobed foliage-leaves. These remarks, incomplete as they are, may suffice to 

 turn the attention of the student to the phenomena of the branching, which are 

 moreover easily observed. 



The Leaves (with the exception of the floral leaves) are either all foliage-leaves 

 containing chlorophyll, as in Araucarta, Juniperus^ Thuja^ &c. ; or all colourless or 

 brownish scales, as in Phyllacladus, where the foliage-leaves are replaced by 

 leaflike shoots ; or, finally, scales and foliage-leaves are very frequently formed at 

 the same time, and even on the same shoots (as in Abies), where the scales only 

 serve the purpose of protecting the buds ; or the two forms are distributed on 

 different axes, as in the true Pines (Pinus), the permanent woody shoots of which 

 produce only membranous scales, the axils of which develope sterile foliage-shoots 

 which afterwards die off. The foliage-leaves of Conifers are mostly small, of simple 

 structure, and scarcely ever compound; they are smallest and at the same time most 

 numerous in the Cupressineae, where they form a dense covering to the axes of the 

 branchlets (as Thuja, Cupressus, &c.) ; in most of the Abietineae and in Taxus and 

 Juniperus, they are larger, more sharply separated from the axis, narrow and com- 

 paratively thick, usually angular and prismatic (acicular); intermediate forms between 

 these acicular leaves and the broad expanded leaves of Thuja occur in Araucaria 

 excelsa, &c. In Podocarpus and Dammara the leaves are flat and broader, and in 

 Salishuria they are stalked and even two-lobed, with a deeply emarginate apex as 

 if from dichotomous division. Not unfrequently, especially in the Cupressinese, 

 the foliage-leaves of the elongated primary axis are different in form from those 

 higher up the same axis and from those on the lateral shoots ; in Thuja, Juniperus 

 virginiana, Cupressus, Sec, the former are acicular, patent, and of considerable size, 

 the latter very small and closely appressed to the axis; the youthful foliage some- 

 times recurs on isolated branches of adult plants. The axis of the shoot within 

 the bud is so densely covered with the bases of leaves that no free portion of the 

 surface of the axis is visible between them. When the axis has attained a con- 

 siderable length on the unfolding of the bud, the bases of the leaves generally grow 

 at the same time in length and breadth, so that they entirely cover the surface of 

 the enlarged shoot also, clothing it wiih a green cortex, in which the parts belonging 

 to the separate leaves can be distinctly recognised. This is especially clear in 

 Araucaria and many species of Pinus, but is very common also in other genera; 

 in Thuja, Cupressus, Libocedrus, &c., the axis of the shoot is also completely 

 covered with these leaf-cushions; but the free parts of the leaves are very small 

 and often project only as short points or projections. The phyllotaxis is spiral 

 in the Abietineae, Taxineae, Araucarieae, Podocarpus, &c. ; the Cupressineae bear 

 whorls which^ above the cotyledons, contain generally from three to five leaves, but 



