. Biological lectures delivered at the Marine Biological Laboratory of Wood's Holl [sic]. Biology. i8o BIOLOGICAL LECTURES. plant can get but little moisture, it also retains that little, or lets it go with great difficulty. Hence, we have on the sea- shore a vegetation corresponding in some respects to that in high altitudes, or to that in desert regions, although the apparent conditions are radically different from either. Hydrocotylc uuibellata is a plant common in moist or watery places from Maine to Florida. In the semi-tropical fresh-water marshes of Florida, it places its slightly thick
. Biological lectures delivered at the Marine Biological Laboratory of Wood's Holl [sic]. Biology. i8o BIOLOGICAL LECTURES. plant can get but little moisture, it also retains that little, or lets it go with great difficulty. Hence, we have on the sea- shore a vegetation corresponding in some respects to that in high altitudes, or to that in desert regions, although the apparent conditions are radically different from either. Hydrocotylc uuibellata is a plant common in moist or watery places from Maine to Florida. In the semi-tropical fresh-water marshes of Florida, it places its slightly thickened, rounded leaves at right angles to the sun's rays, parallel to the surface of the water in which it grows. When it happens to encroach uj^tju the salt-water marshes of this same region the difficulty of water supply is so heightened that the slender petioles all make a right-angled turn at their upper end and put. Fig. b. I' No. 14. the now thickened leaves in a vertical position, in order to avoid the direct rays of tlie sun, thus lessening the loss of water. Plate No. 14. fig. a, shows a sketch of this little jjlant, taken from a fresh-water stream in South Florida. T^ig. b on the same plate shows another plant taken from a salt marsh near by. All of its leaves are rendered vertical b}- this turn in their petioles. The microscopic differences are much greater than this relative difference in position. The leaves of the one in the salt marsh have become much thicker, the epidermal tissues much heavier, the number of the palisade cells has increased, the intercellular spaces have nearly , and the. 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 Marine Biological Laboratory (Woods Hole, Mass. ). Boston, Ginn & Co
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