Organography of plants, especially of the archegoniatae and spermaphyta . ence of Sti-pules. Concrescence of stipulesappears regularly in many plantsand there are two cases :— [a) Concrescence of stipulesof one and the same leaf; {b) Concrescence of stipulesof adjacent leaves. This can onlytake place, of course, where thereis a cyclic phyllotaxy, and it oc-curs especially where there aredimerous whorls ^ Concrescence of stipules ofone leaf. Fig. 241 shows an example of the concrescence of the stipulesof one and the same leaf. Here instead of two separate stipules we find onescale-like structur
Organography of plants, especially of the archegoniatae and spermaphyta . ence of Sti-pules. Concrescence of stipulesappears regularly in many plantsand there are two cases :— [a) Concrescence of stipulesof one and the same leaf; {b) Concrescence of stipulesof adjacent leaves. This can onlytake place, of course, where thereis a cyclic phyllotaxy, and it oc-curs especially where there aredimerous whorls ^ Concrescence of stipules ofone leaf. Fig. 241 shows an example of the concrescence of the stipulesof one and the same leaf. Here instead of two separate stipules we find onescale-like structure ^ which is the result of the union of two stipules, as theapical division in two indicates. How effective is the protection of the budthus provided is shown in the transverse section (Fig. 242). In Diptero-carpus alatus (Fig. 240) the stipules join across the upper side of the leaf-stalk, forming in this way a sheath enveloping the bud, and the formationof the sheath by the concrescence of two stipules can be easily recognizedby the presence of two stipular Fig. 239. To the left: LathjTus heterophyllus : end ofa shoot. To the right: Lathyrus latifolius: node. Theunilateral stipular outgrowths are horizontal in the youngshoot of L. heterophyllus, are directed downwards at theolder node of Lathyrus latifolius. Natural size. ^ The opposite primary leaves of Thaseolus multiflorus furnish an example. The subsequentleaves are alternate, and there is naturally no concrescence. ^ In Onobrychis the concrescent stipules form a dry membranous structure. 368 STIPULES, LI GULES, ST I PELS Concrescence of stipules of adjacent leaves. Concrescence of stipulesbelonging to two separate leaves is frequently observable in the opposite-leaved species of Urticaceae, for example in Humulus Lupulus and ina less degree also in Urtica dioica. Here I have found the two neigh-bouring stipules of one leaf-pair sometimes quite free, sometimes unitedmore or less, and they may form an apparent s
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