Abstracts of Papers - Harvard Forest - Harvard University

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GLIME, JANICE M. Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931. - A photographic study of spore and protonema development in Fontinalis squamosa. Electron microscopy was used to demonstrate development and arrangement of spores within the capsule. Spore viability, germination, and protonema development are illustrated by light and fluorescence microscopy. The presence of two spore sizes is clearly demonstrated and the reduced viability of the smaller spores is demonstrated by reduced fluoresence. Germination is demonstrated in culture from 5?C-22?C and requires light and moisture, but not submersion. Protonemata branches arise from 1-3 points on the spore, depending upon conditions. Germination and development are slow and depend upon the state of maturation of the spores at the time of culture. Bud development is very slow and the requirements for budding are unclear. GOWIAN, SHARON P. Botany Division, National Museum of Natural Sciences, National Museums of Canada, Ottawa, Ontario KIA OM8, Canada - A study of roof- dwelling lichens and the possible effects of a nearby phosphorus plant. Concern has been expressed by the inhabitants of Long Harbour, Newfoundland, about abundance in their town of roof-dwelling lichens, and the possible relationship of their growth to phosphate- and fluoride-con- taining substances escaping from a nearby phosphorus plant. In response to this concern, an ecological study was undertaken to compare the roof-dwelling lichen community in Long Harbour with that in nearby towns lacking any significant sources of atmospheric contamination. Results show a concentration of "enrichment species", especially Xanthoria polycarpa and Physcia tenella in Long Harbour, whereas species characteristic of acid bark and rocks, especially Hypogymnia physodes and H. tubulosa predominate in a nearby town. Coverages and effect of lichens on their substrate in the two towns are comparable. It is hypothesized that the abundance of enrichment species in Long Harbour is at least partially a response to high concentrations of air-borne dust rich in phosphates. GRAHAM, LINDA E. Department of Botany, Univer- sity of Wisconsin, Madison, WI 53706. - Coleochaete: Advanced green alga or primitive embryophyte? Ultrastructural studies of reproductive development in Coleochaete have revealed a number of features that do not occur elsewhere in the green algae, but which are characteristic of embryophytes. Filament- ous species of Coleochaete produce unicellular antheridia as do other green algae, but the parenchymatous species may produce internal, multi- cellular antheridia that resemble early developmental stages of land plant gametangia. Following fertilization, the zygote of Coleochaete is retained on the haploid plant, and apparently induces the formation of a layer of covering cells that may produce localized wall ingrowths. These cells resemble gametophytic placental transfer cells of embryophytes in location, time of development, and ultrastructure. Upon germination, the zygote develops into a multichambered, spore-producing structure that is not observed elsewhere among green algae, but which resembles spore mother cells of embryophytes in some important features. Finally, Coleochaete produces more spores per Bryological and Lichenological Section 5 fertilization elSent than other freshwater, or haploid, haplobiontic green algae. This last feature is probably related to retention of the zygote, zygote enlargement and storage of photo- synthate, and putative nutrient interactions between haploid aind diploid phases of the life cycle. These features may thus have been preadaptations of major importance during the transition of plants to land and the origin of embryophytes from charophycean algae. HOARE, JANET K. Room 429 Hensill Hall, San Francisco State Univ.,San Francisco,CA94132 - Lichen succession ian lava flows. and diversity on dated Hawai- Lichens were collected on lavas of thirty-two ages on the island of Hawaii to determine lichen succession and diversity on a series of lava substrates of known ages. One hundred eighty-six collections 'were made at sixty sites representing nine geographic locations. Stereocaulon is the most prevalent genus and, with Lepraxia, becomes established in less than ten years, fo'llowed by foliose genera (largely Parmelias), and Cladonias. Crustose genera appear on lavas at least thirty years old, but are uncommon on lavas younger than a few hundred years. The greatest lichen diversity was found on old lavas at sea level in the south-east portion of the island where rainfall is moderate. The most profuse growth (Stereocaulon) appears on lavas one hundred and fifty years old in the central saddle area where rainfall is heavy. LAWREY, JAMES D. Department of Biology, George Mason University, Fairfax, VA 22030. - Lichen herbivore ance? behavior: preference or avoid- Field data collected in a saxicolous lichen community in Shenandoah National Park showed that the lichen herbivore Pallifera varia prefers certain lichen species to others. Two hypotheses were developed to explain this preference. The avoidance hypothesis, that preference by slugs actually results from the rejection of unpalatable species, was tested by offering slugs choices of filter paper disks impregnated with secondary products of the avoided and preferred species. The preference hypothesis, that slugs select lichens of highest quality, was tested by measuring the ooncentration of essential elements in lichens eliciting high and low preference by slugs. Lichens with the highest element contents were assumed to be of highest quality to herbivores. Results showed that the preferred lichens had significantly lower concentrations of N, P, and Ca, and that avoided lichens produced secondary compounds that inhibited P. varia grazing activity. These results suggested that lichens with high concentrations of essential elements are most likely to produce defense compounds, an observation supporting some explanations for chemical defense patterns in vascular plants. Mankiewicz, Paul S. Harding Laboratory, New York Botanical Garden, Bronx, New York, 10458 -Water conduction by external capillary spaces and the shape of bryophyte colonies. While the major kinds of bryophyte colonies have been well described in the literature, there have been no empirical studies of the spatial arrangement of plant axes in cushions,
6 Bryological and Lichenological Section wefts, tufts,and canopies of bryophytes. In the present study, two sets of methods have been elaborated: one set of methods permits the external capillary spaces within bryophyte colonies to be visualized by modifi- cations of standard parafin embedding methods, as well as other novel means using colloidal infusions or polymerization; the other set of methods permit direct laboratory dr field measures to be taken of water flow through a bryophyte colony. The results of these methods demonstrate that cushions, wefts, tufts and canopies are: 1)qualatatively distinguishable in terms of the distribution of axes and appendages within the colonies; and,2) quantatively distinguishable in terms of the amount of water that the cross section- al area of a given colony type is capable of transporting. MATTHES-SEARS, UTA and THOMAS H. NASH III. Department of Botany and Microbiology, Arizona State University, Tempe, AZ 85287. - Morphological and physiological variations of Ramalina menziesii along a coast-inland gradient. The corticolous lichen Ramalina menziesii Tayl. shows marked morphological variation along a coast-inland gradient in western California. Photosynthetic patterns throughout the year were studied at a coastal and an inland site and found to differ markedly as a result of the oceanic influence which modifies the moisture aspect of the climate. Both populations became activated by rainfall and dew during the rainy season; these winter photosynthetic rates were generally higher at the coastal than the inland site. During summer, the inland population was inactive due to drought, whereas the coastal population was regularly activated by coastal fog and high atmospheric humidity. Preliminary data show that the finer, less reticulate coastal morphotype was slightly more efficient in absorbing water vapor from the air and consequently exhibited higher photosynthetic rates under conditions of high atmospheric humidity. This suggests an adaptation of the coastal population to utilization of non-precipitation sources of moisture. MILLER, HARVEY A. Department of Biological Sciences, University of Central Florida, Orlando, Florida 32816 - Two hepatic genera new to Hawaii and Polynesia. Among the thousands of unreported collections of Pacific island bryophytes assembled by the author, many specific novelties have been discovered. Two genera found among these collections, Southbya and Aphanolejeunea, have not been reported previously from Hawaii and Polynesia. Southbya is new to all tropical Pacific islands and its presence in Hawaii provides additional evidence for a floristic tie to temperate Asia. Aphanolejeunea was reported by Stephani from Norfolk Island but that questionable record until now has been the sole report for the tropical Pacific. MISHLER, BRENT D .* and STEVEN P . CHURCHILL . Farlow Herbarium, Harvard University, Cambridge, MA 02138 and Division of Biological Sciences, University of Kansas, Lawrence, KS 66045. - On the application of Hennigian bryophytes. cladistics to the phylogeny of the The empirical concern of bryophyte systematists with new methods for studying characters has generated important new data bearing on the relationships of these plants. It is important also, however, to pay explicit attention to the theory behind systematics and the study of phylogeny, to the assumptions, justifications, and even procedures that have usually been left implicit. We argue that the application of Hennigian cladistics to bryology can provide a rigorous framework for investigating phylogeny, sound concepts of monophyly, homology, and relationship, and a maximally useful basis for classification. We present the results of a study of the cladistic relationships of the major groups of bryophytes, with respect to the green algae and the tracheophytes. While the embryophytes as a whole do seem to form a monophyletic group, the bryophytes (sensu lato) are paraphyletic. The mosses appear to have shared a more recent compmon ancestor with the tracheophytes than either has with the liverworts or hornworts. The phylogenetic placement of the hornworts is more problematical, but on the basis of current information, they seem to have shared a more recent common ancestor with the moss-tracheophyte lineage, than with the liverworts. Hennig's central phylogenetic insight, that only shared, derived characters are evidence of relationship, can provide a focus for further research to test and refine the preliminary cladogram presented here. MISHLER, BRENT D.* and DANIEL C. SCHEIRER. Farlow Herbarium, Harvard University, Cambridge, MA 02138 and Department of Biology, Northeastern University, Boston, MA 02115. - Development of the leaf of Tortula obtusissima: systematic and ecological implications. The development of leaves of field-collected and cul- tured plants of Tortula obtusissima (C. Muell.) Mitt. has been studied with light microscopy, SEM, and TEM. Leaves of young gametophores produced from spores show a characteristic juvenile morphology, differing from adult leaves in shape, curvature of the leaf margin, and the merely apiculate apex. The hollow papillae are initially simple, on 3-5 regions of both surfaces of the leaf cell, and develop by enlarging and bifurcating twice, finally becoming antleroid. Leaf ontogeny is of potential phylogenetic importance when compared to other species of Tortula with mature leaf morphologies similar to the juvenile morphology of Tortula obtusissima, and in which the same type of papilla is elaborated to a lesser or greater extent. Mature leaves of Tortula obtusissima are keeled, with recurved margins and a long-excurrent, hyaline, serrate awn. The basal leaf cells are hyaline, rect- angular, often with both surface walls resorbed and standing open wet or dry. The upper leaf cells are strongly mamillose, in addition to bearing the characteristic papillae, and have a cuticle. The leaf morphology appears to have several ecological func- tions. The perforated basal cells and sheathing leaf bases serve for external water transport. The great- ly amplified cell membrane in the hollow papillae implies transport processes--an external analogy to the transfer cells at the foot of moss sporophytes. The papillae, which with the mamillose cell walls form channels for capillary movement of water over the leaf surface, may also serve to facilitate gas exchange during active photosynthesis. NEUMANN, ALAN J. and DALE M. J. MUELLER*. Department of Biology, Texas A&M4 University, College Station, TX 77843. -Structure and function of the peristome in Leucodon julaceus (Musci).
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