. A text-book of botany for secondary schools. Botany. 260 A TEXT-BOOK OP BOTANY certain plants belonging to an adjacent continent may often be explained in this way. 154. Dispersal by animals.—Only a few illustrations of this verj' large subject can be given. Water-birds are great carriers of seeds, which are con- tained in the mud clinging to their feet and legs. This mud from the borders of ponds is usually completely filled with seeds of various plants. One has no con- ception of the number until it is actually computed. The following extract from Darwin's Origin of Species illustrates thi
. A text-book of botany for secondary schools. Botany. 260 A TEXT-BOOK OP BOTANY certain plants belonging to an adjacent continent may often be explained in this way. 154. Dispersal by animals.—Only a few illustrations of this verj' large subject can be given. Water-birds are great carriers of seeds, which are con- tained in the mud clinging to their feet and legs. This mud from the borders of ponds is usually completely filled with seeds of various plants. One has no con- ception of the number until it is actually computed. The following extract from Darwin's Origin of Species illustrates this point: "I took, in February, three tablespoonfuls of taud from three different points beneath the water, on the edge of a Uttle pond. The mud when dried weighed only 6f ounces; I kept it cov- ered up in my study for six weeks, pulling up and counting each plant as it grew; the plants were of many kinds, and were altogether 537 in number; and yet the viscid mud was all contained in a breakfast cup!" Water-birds are generally high and strong fliers, and the seeds may be trans- ported thus to the margins of distant ponds and lakes, and so become very widely dispersed. In many cases seeds or fruits or heads develop grappling appendages of various kinds, forming the various burs, which lay hold of animals brushing past; and so the seeds are dispersed. Common fruits with grappling appendages are Spanish needles Fig 257. — Akene of Spanish nee- dles with barbed appendages.—Af- ter Fig. 25S.—Akene of beggar - ticks with barbed appendages. —After Beal. illustrations of. 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
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