. Our native ferns and their allies : with synoptical descriptions of the American Pteridophyta north of Mexico. Ferns. 48 Our Native Ferns produce long-petioled leaves resembling " four leaf clovers," which float on the surface of water. Others like Azolla are little float- ing plants much resembling a liverwort. Marsilia and Pilularia have a circinate vernation and have therefore received the name of " water ; Mar- silia quadrifolia (Fig. 40) is found on the shores of Bantam Lake, Litchfield Co., Ct.^ where it literally covers the margin of the lake for two miles or
. Our native ferns and their allies : with synoptical descriptions of the American Pteridophyta north of Mexico. Ferns. 48 Our Native Ferns produce long-petioled leaves resembling " four leaf clovers," which float on the surface of water. Others like Azolla are little float- ing plants much resembling a liverwort. Marsilia and Pilularia have a circinate vernation and have therefore received the name of " water ; Mar- silia quadrifolia (Fig. 40) is found on the shores of Bantam Lake, Litchfield Co., Ct.^ where it literally covers the margin of the lake for two miles or more. 116. Fructification.— The fruit of Marsilia con- sists of a hollow stalked receptacle known as the sporocarp\i\vic\i bears the sporangia in sori on the inner walls of its two valves. The spores are of two kinds as in this entire group of plants. 117. Germination.— In Marsilia the anthero- zoids are produced in the microspore itself and are corkscrew-shaped, con- sisting of several coils. The prothallium, devel- oped from the apex of the macrospore, is a hem- ispherical mass of tissue and contains a single archegonium. 118. Geologic Distri- bution.—Four genera are found fossil extending from the Jurassic. Mar- silia and Pilulafia occur in the Tertiary. * This species was first discovered in America by Dr. T. F. Allen some twenty-five years ago in Bantam Lake and is now rapidly increasing. It is probably an emigrant from some distant locality but the method of its introduction is a Fig. 40. Marsilia qiMdrifolia, L. Natural size though the petioles are frequently three times as long. (Original.). 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 Underwood, Lucien Marcus, 1853-1907; Underwood, Lucien Marcus, 1853-1907. Our native ferns and how to study them. Bloomington, Ill. Leader Pub. Co.
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