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Porella pinnata in North America

1968; American Bryological and Lichenological Society; Volume: 71; Issue: 1 Linguagem: Inglês

10.1639/0007-2745(1968)71[29

1938-4378

Henry S. Conard,

Peatlands and Wetlands Ecology

Porella pinnata L. occurs North America from Minnesota, Iowa, and Texas to the Atlantic coast. To the north of the fortieth parallel it is mostly aquatic and sterile; to the south it is generally fertile, rarely or never submerged, and often grows trees, shrubs, and stone walls. The current manuals describe the liverwort Porella pinnata L. consistently, making identification easy, but the usual statements of habitat seem to be copied from one author to another and leave much to be desired. These statements, moreover, are misleading for the habitats the southeastern states. In the northeastern United States pinnata grows attached to stones shallow, swift rivulets. This fresh green, aquatic, sterile form looks so different from the brown, stringy, dry, aerial form of the Southeast, with abundant perianths, that one readily assumes that the forms represent two species. I was impelled to look into the matter by the receipt of an ample fertile specimen from Mrs. Blanche E. Dean of Birmingham, Alabama, who wrote: grows living shrubs and trees and limbs the Fred T. Stimpson Refuge about 15 miles from Jackson, Alabama. I did not find it the ground or rocks. The little shrubs would be covered entirely with it so that no leaves would grow out the plant. I think the most common shrubs it grows were yaupon holly and privet. There was much of it both the dry places as well as damp places. I believe, though that I can say, that it grew only where it was damp or areas where it was flooded a good part of the year. . . . It also grew limbs as high as ten feet up, and trunks of trees .... I was surprised at first to find it growing the woods adjoining salt springs. Porella pinnata is reported from Nova Scotia to Ontario, and from Maine to Minnesota, Iowa (the extreme eastern edge of the state, at Burlington), Missouri, Arkansas, Texas, Tennessee, Louisiana, and Florida. I find no reports from Mississippi or South Carolina. It is known from Europe, and Frye and Clark (1946) report it from Cuba. Collections with perianths are much less common than sterile ones. Professor R. L. Hulbary kindly reports to me that nine out of about 50 collections of it the herbarium of the State University of Iowa have perianths. These are from Delaware, North Carolina, Florida, Louisiana, Arkansas, and Texas. All of the fertile specimens were apparently taken from woody plants moist places. Some are from places subject to flooding, but many are from well above the reach of flood water. Howe (1897) gave the habitat as on banks of shaded streams and rocks and logs subject to overflow, and added usually collected a sterile condition. Evans (1916) stated in North America the species is abundant; Europe exceedingly rare. 1 Lake Hamilton, Florida 33851. This content downloaded from 40.77.167.32 Sun, 31 Jul 2016 05:14:12 UTC All use subject to http://about.jstor.org/terms 30 THE BRYOLOGIST [Volume 71 It grows stones and logs streams as well as the banks, and is completely submerged during part of the year. Apparently the sporophytes reach maturity only when the plants are exposed to the air. Brown (1924) found pinnata at Thomasville, Georgia, on trunk of tree quite three feet up; and trunk of Wisteria. Schuster (1953) summed up the occurrence of the species thus: P. pinnata becomes as ubiquitous the Deep South as it is restricted and rare occurrence the upper Midwest. In the South it occurs as a xerophyte dry rocks, far from any source of constant water (often with platyphylloidea, Radula complanata and obconica, Metzgeria furcata). It is particularly common Taxodium knees and trunks, but may also occur the bark of beeches, together with Frullania squarrosa and other corticolous xerophytes. It seems probable that our northern pinnata represents only one series of closely related genotypes of a larger and diverse series nearer the center of distribution. European bryologists consistently prefer the generic name Madotheca. This was discussed at length by Howe (1897), with a decision favor of Porella; Miiller (1956) more recently maintained Madotheca. Because of its rarity Porella pinnata is almost unknown to European bryologists. Husnot (1922) mentioned nine localities France, but admitted je n'ai pas vu le perianthe. Macvicar (1926) quoted Howe about the perianth, and added Androecium?. Frye and Clark (1946) supply the information briefly: Male inflorescence a short, lateral branch without normal leaves. Miiller (1956) reports the species from Madeira, Portugal, Spain, France, Ireland, and southwestern England. Sporogone sind aus Europa nicht bekannt, he remarked.