. Botany for agricultural students . Botany. CORN ICERNEL 63. The location of the embryo at one side of the endosperm, instead of being centrally located and surrounded by the endosperm, is a peculiar feature of the Grass type of seeds. The embryo consists of two main parts: the large scuteUum or cotyledon (cot) which lies in con- tact with the endosperm, and the embryonic axis which upon germi- nation produces the stem at its upper and roots at its lower end. The axis is attached along its central region to the cotyledon, which suppUes it food during growth. At the upper end of the axis is th
. Botany for agricultural students . Botany. CORN ICERNEL 63. The location of the embryo at one side of the endosperm, instead of being centrally located and surrounded by the endosperm, is a peculiar feature of the Grass type of seeds. The embryo consists of two main parts: the large scuteUum or cotyledon (cot) which lies in con- tact with the endosperm, and the embryonic axis which upon germi- nation produces the stem at its upper and roots at its lower end. The axis is attached along its central region to the cotyledon, which suppUes it food during growth. At the upper end of the axis is the plumule, a small bud- like structure consisting of a grow- ing point (gr) and some small leaves (I). The plumule is en- closed in a sheath (d) called col- eoptile. Between the plumule and the attachment of the coty- ledon is a short stem (st), which theUallayer of cotyledon; cj',coieop with the plumule is often called epicotyl (the portion above the cotyledon). The portion of the axis below the cotyledon consists chiefly of the radicle (r), the struc- ture which develops the first root. The radicle bears at its tip the root cap (re) and is enclosed by the coleorhiza (cr). The hypocotyl, which is all or only a part of the axis between the plumule and radicle (a point in dispute among botanists), is the portion of the axis developing least when the embryo resumes growth. In the Grasses there is very Httle elongation of the hypo- cotyl and, consequently, the establishment of the young plant in the soil and Ught depends mainly upon the growth of the radicle and plumule. The fact that the hypocotyl remains small while the radicle, since it forms the first root, becomes a prominent structure, accounts for the general application of the term rad- icle to all of the lower portion of the axis, and the rare use of the term hypocotyl in connection with grass embryos. Fig. 66. — Section through a ker- nel of Corn, cot, cotyledon; ep, epi- tile; gr, growing point of plumule; I, young le
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1919
