. Practical botany. Botany. THE STEM AJSTD THE LEAF 53 are rapidly dividing to form neA\" ones, or, if not dividing, will begin to do so whenever tliey are placed under favorable conditions. Just back of the growing point ajjjiear little protuberances (7) wliich are to develop into leaves. Further along on the stem, each just forward of a rudimentary leaf, are still more rudimentary branches (5j, b^, and so on). In their youngest condition neither leases nor branches con- tain any fibrovascular bundles, hut these soon appear, as shciwn by the heaA'ily shaded areas in the figure. Once equi
. Practical botany. Botany. THE STEM AJSTD THE LEAF 53 are rapidly dividing to form neA\" ones, or, if not dividing, will begin to do so whenever tliey are placed under favorable conditions. Just back of the growing point ajjjiear little protuberances (7) wliich are to develop into leaves. Further along on the stem, each just forward of a rudimentary leaf, are still more rudimentary branches (5j, b^, and so on). In their youngest condition neither leases nor branches con- tain any fibrovascular bundles, hut these soon appear, as shciwn by the heaA'ily shaded areas in the figure. Once equipped witli bundles for the trans[)ortation of \\ater and food materials, the growth of the young branch into a stem like that from which it sprang, ^\ ith bark, wood, and pith of its o-\\-n, is comparatively rapid. Branches of trees. Ijeing structur- all}^ of the same nature as the stem, form " annual rings," just as the main trunk does. The wood of the branch cuts across the "annual rings'" of the trunk and forms a knot (Fig. 37 ).i 50. Internal structure of the monocoty- ledonous stem. In the very young mono- cotyledon oiis stem of seedlings tlie fibro- vascular bundles are ronstructed like those of dicijtyledons, with the -wriod elements on the one side and the cortical elements on the other, as in Fig. 29. But in the full- grown stems of most monocotyledons the bundles have their vessels and other wood elements arranged in a hollow cylinder „ „ ^ , . , 11 " 1 is, cut-off end of stick, inclosmg that part of the bundle which showing annual rings: corresponds to the portion shown outside ^^' ^^°}' /ormed by ^ , growth of a branch of the cambium rmg m Fig. 29. In the adult monocotyledonous stem (when it is solid) the bundles occur scattered all through the pith, as shown in a section of 1 Knots may also be produced by injuries, but most of those found in ordinary lumber were caused by Fit. .37. Formation of a knot in a tree trunk. Ple
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