. Class-book of botany : being outlines of the structure, physiology and classification of plants : with a flora of the United States and Canada. Botany; Botany; Botany. 48 PHYLLOTAXY, OR LEAF ARRANGEMENT. ease of the subsequent development of the branch, as often occurs in the Berb- eris and larch, their spiral arrangement becomes manifest In the pines the fas- cicles have fewer leaves, their number being definite and characteristic of the species. Thus P. strobus, the white pine, has 5 leaves in each fascicle, P. palustris, the long- leaved pine, has 3, P. inops, 2. 226. The opposite leaved
. Class-book of botany : being outlines of the structure, physiology and classification of plants : with a flora of the United States and Canada. Botany; Botany; Botany. 48 PHYLLOTAXY, OR LEAF ARRANGEMENT. ease of the subsequent development of the branch, as often occurs in the Berb- eris and larch, their spiral arrangement becomes manifest In the pines the fas- cicles have fewer leaves, their number being definite and characteristic of the species. Thus P. strobus, the white pine, has 5 leaves in each fascicle, P. palustris, the long- leaved pine, has 3, P. inops, 2. 226. The opposite leaved type is also spiral. The leaves in each circle, whether two or more, are equidistant, dividing the circumference of the stem into equal arcs. The members of the second circle are not placed directly above those of the first, but are turned, as it were, to the right or left, so as to stand over the intervening spaces. Hence there may be traced as many spirals as there are leaves in each whorl. 227. Decussate leaves result from this law, as in the motherwort and all the mint tribe, where each pair of opposite leaves crosses in di- rection the next pair, forming four vertical rows of leaves. Therefore, it is 228. An established law that the course of development in the growing plant is universally spiral. 'But this, the formative cycle as it is called, has several variations. 94 93 93 6. 92, 98, 94, shewing the course of the spiral thread and the order of the leaf-succession in the axes of elm, alder, and cherry. 95, axis of Osage-orange with a section of the bark peeled, dis- playing the order of the leaf-scars (cycle §). 229. The elm cycle. In the strictly alternate arrangement (elm, linden, grasses) the spiral thread makes one complete circuit and commences a new one at the third leaf The third leaf stands over the first, the fourth over the second, and so on, forming two vertical rows of leaves. Here (calling each complete circuit a cycle) we observe 230. First, That this cyc
Size: 1219px × 2049px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1860, booksubjectbotany, bookyear1861
