. Text-book of botany, morphological and physiological. Botany. 184 MORPHOLOGY OF MEMBERS. developes further only on one side, the new branches always arising either only on the left or only on the right side, 3 from 2, and 4 from 3; every lateral branch thus produces a sympodial system, and in fact a helicoid cyme. If now the basal pieces 2, 3, 4, combined in a sympodial manner on both lateral shoots, are imagined to be much shortened, so that the bases of the lobes 2, 3, 4 come close to the base of the lamina 1, then all the lobes of the leaf will appear to spring from one point, and the lea
. Text-book of botany, morphological and physiological. Botany. 184 MORPHOLOGY OF MEMBERS. developes further only on one side, the new branches always arising either only on the left or only on the right side, 3 from 2, and 4 from 3; every lateral branch thus produces a sympodial system, and in fact a helicoid cyme. If now the basal pieces 2, 3, 4, combined in a sympodial manner on both lateral shoots, are imagined to be much shortened, so that the bases of the lobes 2, 3, 4 come close to the base of the lamina 1, then all the lobes of the leaf will appear to spring from one point, and the leaf is called digitate. It would appear, however, that such leaves may also arise by the formation from the broad end of the young leaf itself, first of a middle lobe, and then of new lateral lobes right and left from above downwards, as in Lupinus, according to Payer's drawings (Organogenie de la fleur, pi. 104). If the lobes remain completely united or have the appearance of a continuous lamella, we have a peltate leaf1. It is impossible to go more into the detail of these processes without numerous illustrations which cannot be given here. Fig. 142 will explain, in conclusion, the origin of the quadripartite lamina of the leaf of Marsilea Drummondi^ according to Hanstein (Jahrb. fur. fiS wissen. Bot. vol. IV). B 3£^\Ka? A The leaf has its origin in a cell of the cone of growth of the stem, which, becoming the apical cell of the leaf, produces two rows of segments from which the right and left halves are formed. Thus a broad cone first arises, growing at its apex, and bent towards the stem (J, B); when this, which is the future petiole, has attained a certain height, it in- creases in breadth right and left. Beneath the still growing apex, D, bs, a protuberance (stb) arises on both sides; and while the latter (destitute of an apical cell) becomes still more arched (C, stb)> the apical growth of the leaf ceases (C, bs), its apical cell disappears, and soon two equally strong
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
