GYMNOSPERMAE. — CONIFER AE. 3 21 



axillary shoots. Many of the Coniferae show great regularity in the position of the 

 developing branches of the first and succeeding orders, and these at the same time 

 increase the regularity of the whole by preserving their relative size. Branches of the 

 first order are often formed on the erect and dominant primary stem in false whorls 

 of several members, one at the close of each period of vegetation, and the same thing 

 is often repeated on the branches themselves, as in Pinus sylvcstris and Araiicaria 

 brasilicjisis, and especially on Phyllocladus trichomanoides and many other species ; 

 but the horizontal branches of the first order more often show a tendency to bilateral 

 branching, as in Abies pecthiata, and sometimes smaller branches appear between 

 these stronger ones which form the main frame- work of the tree, as in Abies excels a. 

 Sometimes the position and growth of the branches is more irregular; the farthest 

 removed from the typical form of growth are the Cupressineae, especially Cupressiis, 

 Thuja and Libocedrus, in which the inclination to bilateral branching which appears 

 in the primary stem is still more pronounced on the lateral shoots^ ; branch-systems 

 of three or more orders of shoots are developed in one plane and in such a manner 

 that each system has a definite general outline and looks more or less like a many 

 times pinnate leaf; in Taxodiuin the foliage-leaves are in two rows on slender 

 branches a few inches long, which in Taxodium distichum fall off in autumn with the 

 leaves and are thus still more like pinnate leaves ; lastly, Phyllocladus has only small 

 colourless scale-leaves on all its verticillate shoots, but from their axils beneath the 

 terminal buds whorls of shoots arise with limited growth, which develope bilateral 

 shoots in the form of flat lobed foliage-leaves. These indications, though sHght in 

 themselves, may serve to draw attention to the nature of the branching in the 

 Coniferae, which is moreover not difficult of observation. 



The leaves of any one plant, putting aside the floral leaves, are either all foliage- 

 leaves containing chlorophyll, as in Araiicaria, Jiiniperiis, Thuja, and others, or all 

 colourless or brownish scale-leaves, as in Phyllocladus, where the foliage-leaves are 

 replaced by leaf-like shoots (phylloclades) ; or lastly scale-leaves and foliage-leaves 

 often occur together and on the same shoots, as in Abies, where the scales serve only 

 to envelope the buds, or the two kinds are distributed on different axes, as in the true 

 Pines, where the persistent woody shoots have only membranous scales with short 

 sterile non-persistent leafy shoots in their axils. The seedlings in the Pines have simple 

 acicular foliage-leaves even on the primary axis, but the normal arrangement of the 

 leaves just mentioned is very early established. The foliage-leaves of the Coniferae are 

 for the most part small, of more simple form and rarely divided ; they are smallest and 

 most numerous in the Cupressineae, where they thickly clothe the axes of the branches, 

 as in Thuja, Cupressus, etc. ; they are larger, more distinct from the axis, narrow and 

 comparatively thick and usually prismatic and angular (acicular) in the majority of the 

 Abietineae, in Taxiis zx\^ Juniper us ; intermediate forms between these needles and the 

 expanded leaves of the Thujeae are to be found in Araiicaria excelsa and some other 



' The tendency to bilateral development appears also on the horizontal lateral shoots of many 

 species of Abies and Pinus, in which the spirally-arranged leaves lean over to the right and left and 

 so form two comb-like rows. In Abies pcctinata this occurs chiefly on shaded brandies (on 

 specimens grown in the shade or otherwise), while on those wliich are more strongly illuminated 

 the leaves are not placed at right angles to the direction in which the light falls on them, but arc 

 more or less radially directed. 

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