The elements of botany for beginners and for schools . same point. The so-called Fascicled or Clustered leaves arethe leaves of a branch the nodes ofwhich are very close, just as they arein the bud, so keeping the leaves in acluster. This is evident in tlie Larch(Fig. 184), in which examination showseach cluster to be made up of nume-rous leaves crowded on a spur or shortaxis. In spring there are only suchclusters; but in summer some of themlengthen into ordinary shoots with scat-tered alternate leaves. So, likewise,each cluster of two or three needle-shaped leaves in Pitch Pines (as in Fig. 1
The elements of botany for beginners and for schools . same point. The so-called Fascicled or Clustered leaves arethe leaves of a branch the nodes ofwhich are very close, just as they arein the bud, so keeping the leaves in acluster. This is evident in tlie Larch(Fig. 184), in which examination showseach cluster to be made up of nume-rous leaves crowded on a spur or shortaxis. In spring there are only suchclusters; but in summer some of themlengthen into ordinary shoots with scat-tered alternate leaves. So, likewise,each cluster of two or three needle-shaped leaves in Pitch Pines (as in Fig. 185), or of five leavesin White Pine, answers to a similar extremely short branch,springing from the axil of a thin and slender scale, whichrepresents a leaf of the main shoot. For Pines produce twokinds of leaves, — 1. primary, the proper leaves of the shoots,not as foliage, but in the shape of delicate scales in spring,which soon fall away; and 2. secondary, ihe/ascieled leaves,from buds in the axils of the former, and these form theactual Fig. 183. Whorled leaves of Galium. FiQ. 184. A piece of stem of Larch with two clusters (fascicles) of numerousleaves. FlQ. 185. Piece of a hvanch of Pitch Pine, with three leaves in a fascicle or bun-dle, in the axil of a thin scale which answers to a primary leaf. The bundle is sur-rounded at the base by a short sheath, formed of the delicate scales of the axillarybud. SECTION 7.] THEIR AERANGEMENT, 69 185. Phyllotaxy of Alternate Leaves. Alternate leaves are distrib-uted along the stem in an order wliicli is uniform for each species. Thearrangement in all its modifications is said to be spiral, because, if wedraw a line from the insertion, (i. b. the point of attachment) of one leaf tothat of the next, and so on, this line will wind spirally around the stem asit rises, and in the same species will always bear the same number of leavesfor each turn round the stem. That is, any two successive leaves willalways be separated from
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1887
