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The sporophyte of Leucodon julaceus (Hedw.) Sull. has a peristome consisting of a reduced endostome and an exostome of sixteen stout, pale teeth that are orna- mented with papillae on the upper two-thirds of the teeth. The endostome is composed of cellulosic primary cell walls of the inner (IPL) and primary (PPL) peristome layers, plus heavy secondary wall thickenings on the IPL which appear to be of carbohydrate and lipid composition. The exostome is composed of portions of adjacent periclinal cell walls of the PPL and outer (OPL) peristome layers and a common middle lamella. The middle lamella is composed of pectin- aceous and lipoidal compounds. The adjacent primary walls of the PPL and OPL are composed of densely packed cellulosic microfibrils. The primary walls are highly birefrigent and the main axis of microfibril orientation is parallel to the longitudinal axis of the tooth. Secondary wall thickenings are heaviest along the PPL and consist of cellulosic microfibrils embedded in a matrix of other carbohydrate and lipoidal compounds. The basal one-third of the exostome exhibits the heaviest secondary thickenings on the inner lamellae. The peristome functions in the regulation of spore release and is classified as hydrocastique because spore release is favored during periods of high humidity). The secondary wall thickenings at the base of the inner lamellae of the exostome swell upon hydration, causing the teeth to reflex to an erect position, thus allowing unhindered release of spores from the urn. Upon dehydration, these thickenings of the inner lamellae shrink causing the teeth to inflex over the mouth of the urn. OLAFSEN, ASTRID G. * and THOMAS H. NASH III. Department of Botany and Microbiology, Arizona State University, Tempe AZ 85287. - Patterns in carbon and nitrogen fixation in two lichens from arctic habitats. Peltigera canina and Stereocaulon tomentosum, two disparate nitrogen-fixing species, were monitored diurnally in situ throughout the summer at Anaktuvuk Pass, Alaska. Nitrogen fixation showed greter responses to changes in thallus water content (%oven dry weight) than did carbon fixation. At thallus water less than 250% (P. canina) and 160% (S. tomentosum), nitrogen fixation declined, almost ceasing at 100%, in contrast to carbon fixation, which began dropping rapidly at 100% for both species. Above 250% and 160%, nitrogen fixation increased gradually, peaking at 300% and 200% for P. canina and S. tomentosum, respectively. Carbon fixation plateaued at water greater than 100% for both species, with no decline at high water contents, which never exceeded 520% for P. canina nor 350% for S. tomentosum. Nitrogen fixation increased with temperature, both species having their highest activity (15 nmoles C2H4 mg-lhr-l (P. c.) and 4.2 nmoles C 2H4 mg-lhr-l (S. t.)) recorded at 19-21? C, while any photosynthetic increase with temperature was indistinguisable from the light effect. Gross photosynthesis saturated at 260-320 ,uE (.28 cal cm 2min 1) for P. canina, and 100 ,uE higher for S. tomentosum, with nightime fixation 5-10% of daytime levels; nightime nitrogen fixation continued on par with daytime levels, showing no increase with increased light. Since 90% of the observed light levels and 80% of the observed temperatures of physiologically active samples were at or below these optima, photosynthesis both species were light and temperature limited limited for for nitrogen fixation through most of the season. Bryological and Lichenological Section 7 RUSHING, ANN E.*, ZANE B. CAROTHERS AND JEFFREY G. DUCKETT. Department of Botany, University of Illinois, Urbana, IL 61801 and School of Biological Sciences, Queen Mary College, Mile End Road, London El 4NS. U.K. Some aspects of spermatid microanatomy in the Jungermanniales. A comparative study of the locomotory apparatus and cytoskeleton of Cephalozia lunulifolia and Chiloscyphus pallescens (Jungermanniales) has revealed numerous similarities between these two species and notable differences from previously investigated hepatics. In both species, the spermatid mother cells undergo ovalization prior to the final mitotic division, and the multilayered structure (MLS) shows the typical 4-layered morphology. In Cephalozia, the anterior portion of the lamellar strip (LS) is wider on both sides than the narrow anterior portion of the spline but is equal in width to the sDline at its maximum. Similar lateral extensions of the LS were not observed in Chiloscyphus. At its widest, the spline of Cephalozia comprises 17 microtubles while that of Chiloscyphus comprises 25. The spline narrows gradually to form a shank usually made up of 6 long tubules. The anterior basal body (ABB) occupies a subapical position; the triplet extensions of the posterior basal body (PBB) extend forward and overlap with the ABB. The anterior mitochondrion (AM) follows closely the outline of the LS and may extend posteriorly beyond the LS where it then underlies the spline. The posterior mitochondrion, in certain sections, is seen to nearly ensheath the spherical, starch-containing plastid, a condition more commonly seen in mosses. The starch grains show a clumped arrangement. In contrast, the spermatids of Marsupella, the only other jungermannialian genus to be studied in detail, show no overlap of the ABB and the PBB or their extensions and the starch grains are linearly arranged in the plastid. SCHAFFER, KAREN L. Department of Botany, University of Iowa, Iowa City, IA 52242. - Development of papillae on stem leaves of Thuidium delicatulum (Hedw.)BSG. The development of papillae on upper cells of stem leaves of Thuidium delicatulum was investigated with light, scanning and transmission electron microscopy. Initially, through a combination of cell wall deposition and expansion, a small protuberance forms in the central portion of the cell wall. At this point the cell wall is very thin, but inner and outer layers are differentiated. The protoplast extends into the lumen of the developing papilla. As a result of further deposition of inner cell wall material, the papilla continues to enlarge and there is a progressive thickening of the entire cell wall. Associated with this stage is the occurrence of tubular vesicles that originate inside the protoplast and possibly contain wall precursor material. These vesicles are closely associated with the plasmalemma. Also, microfibril formation has been observed on the side of the plasmalemma adjacent to the cell wall. Ultimately, the papillae are more- or-less solid structures that are composed primarily of inner wall material. Although the papillae that occur on mature stem leaf cells of Thuidium delicatulum are simple, the developmental stages are fundmentally the same as those that have been established previously for the branched papillae that characterize upper leaf cells of Anomodon attenuatus (Hedw.) Hub.
8 Bryological and Lichenological Section SHAW, A. JONATHAN. Herbarium, University of Michigan, Ann Arbor, MI 48109 - Peristome Morphology and Homology in Mielichhoferia. The peristome of M. mielichhoferi has traditionally been considered single and endostomial. However, new observations provide evidence that it is double, consisting of more or less well-developed exostome teeth and a rudimentary, endostomial basal membrane. Other Mielichhoferia species whose peristomes have been incorrectly interpreted as single and endostomial include M. himalayana, M. macrocarpa, and M. lahulensis. Many tropical Mielichhoferias do have peristomes consisting of endostome only, but there is much variation in structural detail. Observations on Mielichhoferia, as well as selected other diplolepideous taxa, support Philibert's contention that the endostome is two layered, consisting of inner and outer cell wall plates. SIGAL, LORENE L. Oak Ridge National Laboratory, P.O. Box X, Oak Ridge, TN 37830.1 - Lichen research and regulatory decisions. During recent years, in response to an increased awareness of the adverse consequences of air pollution, the government has enacted legislation that is of interest to lichenologists. This report discusses the role that lichen research has had in the development of this legislation or in decisions made as a result of the legislation. The major acts of interest are the National Environmental Policy Act of 1969 and the Clean Air Act Amendments of 1970 and 1977. Under the Clean Air Act, the Environmental Protection Agency established the National Ambient Air Quality Standards, the Prevention of Significant Deterioration class I, II, III areas, and the "adverse impact" determination for class I areas. In order to make enlightened decisions on environmental issues related to these regulations, data are needed that define: 1) terminology such as "adverse impact," acceptability, significance, reversibility, etc.; 2) dose-response functions, including chronic effects and effects of pollutant combinations; 3) differential sensitivities of species; 4) abundance of natural populations; 5) understanding of inter- and intra-specific relations; and 6) the role of the organism in the structure and function of ecosystems. Lichen research has addressed some of the preceding points, but the necessary data for others are lacking. Evaluation of existing research has identified information gaps and suggested avenues of future research not only for lichenologists interested in air pollution but also for those interested in ecology, population biology, and physiology. 1Operated by Union Carbide Corporation under contract W-7405-eng-26 with the U.S. Department of Energy. SMITH, CLIFFORD W.* & WILLIAM J. HOE. Department of Botany, University of Hawaii at Manoa, 3190 Maile Way, Honolulu, HI 96822, and Herbarium Pacificum, Bishop Museum, P.O. Box 19000-A, Honolulu, HI 96819. - Bryophytes and lichens atop Mauna Kea, Hawaii. Mauna Kea above 13,000 ft. is a bleak area which had remained relatively unaffected by modern civilization until it became the site of several astronomical observatories. It is an ideal site for such studies because of its general aridity and unpolluted atmosphere. A survey conducted to provide baseline information for an environmental impact statement for further development of the area demostrated the presence of 11 mosses (including one new species) and 22 lichens. No liverworts were found. Six species were new records to the Hawaiian Islands. Most species are found in highly protected areas though Umbilicaria hawaiiensis and Pseudephebe pubescens are found on rock faces fully exposed to the prevailing winds. The cinder cones were poor habitat except in spatter ramparts. The lava flows supported the richest flora particularly on west-facing aspects. Lake Waiau, a permanent lake at 13,000 ft. on the south side of the mountain, had a very poor flora even though the area is immersed in late afternoon fog particularly in the summertime. The absence of fruticose species in this situation may be the result of freezing temperatures every night of the year. STARK, LLOYD R. Department of Biology, 202 Buckhout Laboratory, The Pennsylvania State University, University Park, PA 16802. - Life history studies on Forsstroemia trichomitria (Hedw.) Lindb. (Cryphaeaceae). Populations of Forsstroemia trichomitria in central Virginia initiate perigonia and perichaetia along same stems during June. Inflorescences are produced on current cycle stems only, and maturation of inflorescences is acropetal. In most cases, the arrangement of inflorescences is gonioautoicous. The interval of fertilization extends from mid-August through September, with young embryos first observed in September. These embryos are hyaline for several weeks and exhibit very slow development. Near the onset of winter, the embryos cease growing and become chlorophyllose. Both stem and sporophyte elongation are apparently negligible during the winter months. Resumption of growth in the spring entails renewed embryonic and stem elongation. The embryonic phase is broken near the end of July, as setae elongate. Capsule expansion begins shortly thereafter, extending through September. Spore development is slow, and opercula do not fall until February of the ensuing winter. Thus while a set of gametangia is initiated and matured in the same growing season, sporophyte maturation takes approximately 17 months. Hence, during the months of September-February, two sporophyte generations occur simultaneously on the same stem. THOMAS, R. J.* and JAMES G. ELLIS. Department of Biology, Bates College, Lewiston, ME 04240. - Phototropic curvature of Pellia sporophytes. Positive phototropic curvature of elongating liver- wort sporophytes was described by Askenasy as early as 1874, but has only been studied sporadically since that time. The response is of interest in that: (1) it is rapid (occurring within 20-60 minutes after ex- posure to unilateral illumination); (2) it is sensi- tive (blue wavelengths of light being the most effec- tive); and (3) it is not possible to separate the response from the site of perception. Removal of api- cal spore capsules from Pellia epiphylla sporophytes, for example, has little effect on the phototropic responses of sporophyte stalks. Localized unilateral illumination of sporophyte stalks results in curvature at the point of illumination only, with no transmission of the stimulus. Acid ef flux, as deter- mined by agar-dye techniques (Mulkey and Evans, 1981 - Science), is also associated with localized regions of curvature. Owing to (1) the simulation of curvature using localized application of indole-3-acidic acid in lanolin paste, and (2) a presumed relation-
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