. Adventures with animals and plants. Biology. PROBLEM 3. Hov) Complex Flams Reproduce prothalli that the asexual as well as the sexual stage can be studied only under the microscope. (Optional) Reproduction in mosses. Alosses, too, reproduce by asexual and then by sexual reproduction in regular succession; that is, they also have an al- ternation of generations. A moss plant consists of small, green, closely-bunched leaves, and tiny stemlike and rootlike parts. At certain times of the year you may have seen a tall stalk with a spore case (sporangium) at its top attached to this leafy plant. T
. Adventures with animals and plants. Biology. PROBLEM 3. Hov) Complex Flams Reproduce prothalli that the asexual as well as the sexual stage can be studied only under the microscope. (Optional) Reproduction in mosses. Alosses, too, reproduce by asexual and then by sexual reproduction in regular succession; that is, they also have an al- ternation of generations. A moss plant consists of small, green, closely-bunched leaves, and tiny stemlike and rootlike parts. At certain times of the year you may have seen a tall stalk with a spore case (sporangium) at its top attached to this leafy plant. The spore case is filled with many spores which form by asex- ual reproduction. When ripe the spores may become scattered. On the moist earth each spore can grow into a branch- ing chain of cells (called proto77efna), which is green, somewhat like some of the simple algae. Buds form on this thread, and each bud can grow into a leafy moss plant. In time two kinds of reproductive organs are produced by the leafy plants. One kind produces eggs and the other kind produces sperm cells. The sperm cells, like those of the fern, can move about in a film of moisture. Fertilization occurs, that is, the moss plant has sexual reproduction. From the fertilized egg cell, the stalk bearing the spore case described above develops. It looks like a true part of the leafy moss plant; it is really a separate plant which lives as a sort of parasite, getting part of its food from the leafy moss plant on which it grows. Vegetative reproduction. If a farmer or gardener wants a crop of potatoes, he does not plant seeds. Neither does the man who raises sugar cane or straw- berries plant seeds. If you have a be- 447. Spore case. 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 Kroeber, Elsbeth, 1882-; Wolff, Walter Harold, 1901-. Boston
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