. La fougère alliés de l'Amérique du nord au nord du Mexique. Pteridophyta, la botanique. 224 L'isoètes aquatiques. Le ^uillwort le lac. Le {Isoctcs lacnstris lac engelmann) n'a pas été nommé parce qu'il s'agit de l'quillwoi't de nos lacs, mais parce qu'il a été trouvé et est assez abondant dans les lacs de l'Europe. Il y a de bons botanistes qui doute qu'il ne l'a jamais été trouvé en Amérique, bien qu'il était souvent re- porté par les premiers collectionneurs. Cependant, à l'époque, il était habituel de voir toutes nos usines d'espèces de l'Ancien Monde MeglTpore de d'apparence semblable, et ce explanis} probabl' les nombreux rapports de

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. The fern allies of North America north of Mexico. Pteridophyta; Botany. 224 THE AQUATIC QUILLWORTS. The Lake ^uillwort. The lake quillwort {Isoctcs lacnstris) was not named because it is the typical quillwoi't of our lakes, but be- cause it was first found and is quite abundant in the lakes of Europe. There are good botanists who doubt that it has ever been found in America, though it was often re- ported by early collectors. At that time, however, it was customary to refer all our plants to Old World species MeglTpore of of Similar appearance, and this probabl}' explanis the many reports of its occur- rence in regions where nowadays it cannot be found. Isoetes lacustris is described as having from ten to thirty dark-green leaves from three to six inches long. There are no stomata in the leaves, and the indusium cov- ers about one third of the unspotted sporangium. The megaspores are from 500/^ to 8001" in diameter, marked all over with short, thin, wavy ridges. The microspores are 35 1" to 45 j" long, light grey, and smooth. The Ameri- can plant differs from the European in the larger mega- spores, and Durieu proposed that it be called Isoetes macrospora. It would seem wise, in view of the appar- ent absence of true Isoetes lacustris, to refer all oiir plants to Isoetes macrospora. Mr. A. A. Eaton concurs in this opinion, but since Isoetes lacustris has long had a place in our flora we have here included Isoetes macrospora with it. The typical Isoetes lacustris is spread widely through the lakes of northern Europe, and is well enough known to receive the common name of " Merlin's grass." It grows in from one to six feet of water. Fish are said to be fond of the tender leaves, and are reported some-. 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 work.. Clute, Willard Nelson,

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