. Plant studies; an elementary botany. Botany. !7J: PLANT STUDIES ;:^ leaves expanded to the air and sunlight, the plautlet has become independent (Fig. 331). It must not be supposed that all of tlie details just given apply to tlie germination of all seeds, for there are certain notable variations. For ex- ample, in the pea and acorn the cotyledons, so gorged with food as to have lost all power of acting as leaves, are never extricated from the seed-coats, but the stem tip. which lies between tlie cotyledons, is pushed out by the elongation of the cotyledons at base into short or sometimes lo
. Plant studies; an elementary botany. Botany. !7J: PLANT STUDIES ;:^ leaves expanded to the air and sunlight, the plautlet has become independent (Fig. 331). It must not be supposed that all of tlie details just given apply to tlie germination of all seeds, for there are certain notable variations. For ex- ample, in the pea and acorn the cotyledons, so gorged with food as to have lost all power of acting as leaves, are never extricated from the seed-coats, but the stem tip. which lies between tlie cotyledons, is pushed out by the elongation of the cotyledons at base into short or sometimes long stalks. In the ce- reals, as corn, wheat, etc., the em- bryo lies close against one side of the seed, so that it is completely exposed by the splitting of the thin skin Avliich covers it. In such a case tlie cotyledon is never un- folded, but remains as an absorbing organ, while the root extends in one dii'cction, and the stem, with its succession of unsheathing leaves, develops in the other. 248. Summary from Angiosperms. âAt the beginning of this chapter (§ 237) the characters of the Gym- nosperms were summarized which distinguished them from Angio- sperms, whose contrasting charac- ters may be stated as follows : (1) The microspore (pollen- grain), cliicfly l\y insc(^t pollination, is l)r(night into contact with the stigma, whicli is a recep- tive region on the surface of the carpel, and there de-. Fri;. 331. Scedlingof liazcl ( Car- /n/"fs). showing primary root (/nv) beriring rootlets {,svr) upon which arc iiiinu'roiis root hairs (/â ). liyiiocoty] (A), cotyji'dons (r), yoiniL,^ stem i' I, inid lirst (/I and second (/') true leaves.âAfter Scuim- I' Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928. New York, D. Appleton and Company
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