. Elementary botany . Fig. 64. Female plant (gametophyte) of a moss (mnium), showing rhizoids below, and the tuft of leaves above, which protect the archegonia. leaf and scale bearing; ex., lily. Thorns, stout, thick, poorly developed bran- ches with rudiments of leaves (scales); ex., hawthorn. Tendrils, slender reduced stems. Flower axes (see morphology of the angio- sperms). 174. Leaf series.—Besides the foliage leaves, the following are some of their modifications: Flower parts (see morphology of the angio- sperms). Bracts and scales, small, the former usually green (flower bracts), the lat
. Elementary botany . Fig. 64. Female plant (gametophyte) of a moss (mnium), showing rhizoids below, and the tuft of leaves above, which protect the archegonia. leaf and scale bearing; ex., lily. Thorns, stout, thick, poorly developed bran- ches with rudiments of leaves (scales); ex., hawthorn. Tendrils, slender reduced stems. Flower axes (see morphology of the angio- sperms). 174. Leaf series.—Besides the foliage leaves, the following are some of their modifications: Flower parts (see morphology of the angio- sperms). Bracts and scales, small, the former usually green (flower bracts), the latter usually chloro- phylless. Bud scales are sometimes green. Tendrils, modifications of the entire leaf (tendrils of the squash where the branched tendril shows the principal veins of the leaf), modification of the terminal pinnae of the leaf (vetch), etc. Spines (examples are found in the cacti, where the stem is enlarged and green, function- ing as a leaf). Other modifications occur as in the pitcher plant, insectivorous plants, etc. 175. The root shows less modification. Be- sides normal roots, which are fibrous in most small plants and stout in the larger ones, some of the modifications are found in fleshy roots, where nourishment is stored (ex., dahlia, sweet potato, etc.), aerial roots (ex., poison ivy, the twining form), aerial orchids, etc. For modifications of roots due to symbiotic fungi, see chapter on Nutrition in Part III.
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