. Plant studies; an elementary botany. Botany. BOOTS 9::: through the holes, so that the seeds rest on the paper, and the root tips hang through the holes. If the paper is kept moist germination will continue, but geotropism will direct the root tips downwards and hydrotropism (response to the moist paper) will direct them upwards. In this way they will pursue a devious course, now directed by one influence and now by the other. If a root system be examined it will be found that when there is a main axis (tajj root) it is directed steadily downwards, while the branches are directed differently
. Plant studies; an elementary botany. Botany. BOOTS 9::: through the holes, so that the seeds rest on the paper, and the root tips hang through the holes. If the paper is kept moist germination will continue, but geotropism will direct the root tips downwards and hydrotropism (response to the moist paper) will direct them upwards. In this way they will pursue a devious course, now directed by one influence and now by the other. If a root system be examined it will be found that when there is a main axis (tajj root) it is directed steadily downwards, while the branches are directed differently. This indicates that all parts of a root system are not alike in their response to these influ- ences. Several other influences are also con- cerned in directing soil roots, and the path of any root branch is a result of all of them. How variable they are may be seen by the numerous directions in which the branches travel, and the whole root system preserves the record of these numerous paths. (2) The pull on the stem.— Another root property may be noted in connection with the soil root, namely the pull on the stem. When a strawberry runner strikes root at tip (see Fig. 47), the roots, after they obtain anchorage in the soil, pull the tip a little beneath the surface, as if they had gripped the soil and then slightly contracted. The same thing may be observed in the process known as. Fiq. 88. A section through the stem of a w&ter- wort (HZatine\ showing the remarkably large and regularly arranged air passages for root aeration. The single reduced vascular bundle is central and connected with the small cor- tex by thin plates of cells which radiate like the spokes of a wheel.—After 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 Comp
Size: 1603px × 1559px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorcou, bookcentury1900, bookdecade1900, booksubjectbotany
