. Lessons with plants. Suggestions for seeing and interpreting some of the common forms of vegetation. Fig. leaves. stalklet of its own. These stalklets, then, aresecondary petioles, or petiolules. 91. Bean leaves (Fig. 82) are seen to be com-pound, with both petiole and petiolules. Moreover,these petiolules are provided with little stipules, orstipels. Let the pupil now determine if there is a 86 LESSONS WITS PLANTS joini at any place on the petiolules at which pointthe three parts may break off in the fall; and isthe Virginia creeper like the bean in this respect?92. The leaf of the
. Lessons with plants. Suggestions for seeing and interpreting some of the common forms of vegetation. Fig. leaves. stalklet of its own. These stalklets, then, aresecondary petioles, or petiolules. 91. Bean leaves (Fig. 82) are seen to be com-pound, with both petiole and petiolules. Moreover,these petiolules are provided with little stipules, orstipels. Let the pupil now determine if there is a 86 LESSONS WITS PLANTS joini at any place on the petiolules at which pointthe three parts may break off in the fall; and isthe Virginia creeper like the bean in this respect?92. The leaf of the Canada thistle (Fig. 83),—and of most other thistles,—is variously cut orjagged, but is nowhere completely separated, and isnot, therefore, a compound leaf. We have seen,then, that there are various gradations between thesimple leaf (that is, one in which the blade is one. FiQ. thistle. more or less continuous piece, as in Figs. 72, 73,74, 77, 78), and the compound leaf. In the truecompound leaf the parts are generally articulated(or separated by joints), and are, therefore, usu-ally provided with petiolules, although these aresometimes wanting. The different parts may fallindependently of the entire leaf, or they maynot. 93. Inasmuch as there seems to be a well THE COMPOUND LEAF 87 marked difference between the distinct divisions inthe Virgiaia creeper and the ill-defined ones ingrape and Canada thistle, we may give the twotypes different names. Or, the parts of a com-pound leaf are leaflets; the deep cut parts, likethose in the thistle, are divisions or segments; theshallower parts (ordinal!] y not extending more thanhalf way to the midrib) are lobes, as in Suggestions.—The pupil will now find himself applying the fore-going tests to all the leaves which he meets. Let him determinewhether any plant bears both simple and compound l
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Keywords: ., bookauthorbai, bookcentury1900, bookdecade1900, booksubjectbotany
