Organography of plants, especially of the archegoniatae and spermaphyta . g. 282). 2. The scutellum is the coty-ledon, and the epiblast which lies overagainst it, but is not present in all grasses, is an arrested second leaf, and the coleoptile is the third leaf. This view is supported by the following:— {a) Between the coleoptile and the scutellum, there is in many grassesa strongly developed internode. {b) In the axil of the coleoptile an axillary bud is often found. {c) The basal part of the scutellum in many grasses, for example Oryza(Fig. 281, V), Leersia, and others (Fig. 281, I) develop
Organography of plants, especially of the archegoniatae and spermaphyta . g. 282). 2. The scutellum is the coty-ledon, and the epiblast which lies overagainst it, but is not present in all grasses, is an arrested second leaf, and the coleoptile is the third leaf. This view is supported by the following:— {a) Between the coleoptile and the scutellum, there is in many grassesa strongly developed internode. {b) In the axil of the coleoptile an axillary bud is often found. {c) The basal part of the scutellum in many grasses, for example Oryza(Fig. 281, V), Leersia, and others (Fig. 281, I) develops like the sheath of ^ These are most fully depicted by E. Bruns, Der Grasembryo, in Flora, Ixxvi (Er<;anzungsbandznm Jahrgang 1892). The literature is cited there. ^ Van Tieghems statement that the embryo is completely surrounded by the nitrogenous layer of theendosperm is not true for Triticum vulgare. See Van Tieghem, Morphologic de Iembryon et de la plan-tule chez les Graminees et les Cyperac&s, in Annales des sciences natnrelles, sen S, iii (1897% p. Fig. 278. Portion ot grain of wheat in medianlongitudinal section. To the left the embrjo. Sc,scutellum ; /, ligule ; vs, vascular supply ofscutellum;Ct\ cylindric epithelium of scutellum; c, cotylarsheath ; pz>, vegetative point of stem ; ///, h^-pocotyl;/, epiblast; r, root; cl, root-sheath ; , fruit-stalk ; f/, vascular supplyof fruit-stalk: f, lateral wall of the fork of the 14. Lehrb. 4i6 TRANSFORMED LEAVES the foliage-leaves of many Monocotyledones. It would therefore be extra-ordinary were there the formation of a second sheath in the coleoptile ^ 3. Scutellum and coleoptile form together the cotyledon, the epiblastis not a leaf. This view would bring the formation of the organs in the embryo ofthe grasses into conformity with that of the Monocotyledones mentionedabove, and it has therefore upon comparative grounds great probability. Let us now pass in review the relationshipsbetween the em
Size: 1516px × 1648px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookido, booksubjectplantanatomy
