. Plants; a text-book of botany. Botany. 120 PLANT STEUCTUEES radial, in contrast with, the dorsiventral thallns, referring to the fact that it is exposed to similar conditions all aronnd, and its organs are arranged about a central axis like the parts of a radiate animal. This position is much more favorable for the chlorophyll work than the dorsiventral posi- tion, as the special chlorophyll organs (leaves) can be spread out to the light freely in all directions. It should be re- marked that the gam- etophyte in all groups of plants is a thalliis, doing its chlorophyll work, when it does any
. Plants; a text-book of botany. Botany. 120 PLANT STEUCTUEES radial, in contrast with, the dorsiventral thallns, referring to the fact that it is exposed to similar conditions all aronnd, and its organs are arranged about a central axis like the parts of a radiate animal. This position is much more favorable for the chlorophyll work than the dorsiventral posi- tion, as the special chlorophyll organs (leaves) can be spread out to the light freely in all directions. It should be re- marked that the gam- etophyte in all groups of plants is a thalliis, doing its chlorophyll work, when it does any, in a dorsiventral position ; the only ex- ception being the ra- dial leafy branch that arises from the thal- lus of Mosses. From j\Iosses onward the gametophyte becomes less conspicuous, so that the prominent leafy plants of the higher groups hold no relation to the little erect leafy branch of the ]\Iosses, which is put out by the gametophyte, and which is the best the gametophyte ever does toward getting into a bet- ter position for chlorophyll work. The leafy branch of the ]\Iosses usually becomes inde- pendent of the thallus by putting out rliizoids at its base. Fig. 102. A moss {Bryum), showing base of a leafy branch (gametophorc) attached to the protonema. and having sent out rhizoids. On tlie protuncma] filament to the right and be- low is the young bud of another leafy branch. —]\ 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
Size: 1294px × 1931px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1900
