Obligate Epiphyte Research Articles

<p><strong><em>Meteoridium </em>and <em>Zelometeorium </em>in Bolivia</strong></p>

The genera Meteoridium and Zelometeorium are described and illustrated from 73 collections made by the author in Bolivia. Barbella tenuissima (Hook. & Wils.) Fleisch. is transferred to the genus Meteoridium as Meteoridium tenuissimum (Hook. & Wils.) M. Lewis comb. nov. Due to its hypnobryoid peristome and other characters, the genus Meteoridium is placed in the Brachytheciaceae. Meteoridium remotifolium (C. Müll.) Manuel shows marked variation over its altitudinal range and four ecoforms are recognized. Distribution records show that the species of these two genera have distinct ranges, with only Meteoridium remotifolium overlapping the ranges of the other species. Habitat data shows that none of the species treated are obligate epiphytes, and that they grow equally well in terrestrial habitats.

Patterns of fucoid reproductive biomass allocation

The reproductive biomass allocation patterns (i.e. total reproductive effort) for eight perennial Northwest Atlantic fucoid algae (Ascophyllum nodosum, A. nodosum ecad scorpioides, Fucus distichus ssp. anceps, F. d. distichus, F. d. edentatus, F. d. evanescens, F. spiralis and F. vesiculosus) are compared from a variety of open coastal and estuarine sites. Three major spatial patterns of total reproductive effort were evident along a strong open coastal-estuarine gradient: (1) estuarine enhancement (e.g. A. nodosum and F. d. evanescens); (2) open coastal enhancement (e.g. F. spiralis); and (3) pronounced localized differences. Several plants from high energy environments (e.g. extreme wave action and strong tidal currents) were stunted and had reduced total reproductive effort, while contrasting patterns were evident for sheltered populations. Ascophyllum from exposed open coastal sites was heavily colonized by the obligate epiphyte, red alga Polysiphonia lanosa, with epiphyte density being significantly correlated with the host's total reproductive effort. Except for the salt marsh ecad scorpioides of A. nodosum, which had sporadic and reduced patterns of total reproductive effort (X = 0·4%) vs. its attached “progenitor” A. nodosum (X = 53% or 132 times higher), each fucoid taxa exhibited a pattern of high reproductive biomass allocation (X = 52–62%). The uniformity of total reproductive effort within the F. distichus complex (52–62%) is surprising as its four subspecies exhibit unique distributional patterns. Several spatial and genotypic patterns (i.e. between taxa) are discussed in terms of varying physiological tolerances, recruitment ecologies, selection, and competition for resources.

The growth patterns of some hydroids that are obligate epiphytes of seagrass leaves

The growth patterns of some hydroids that are obligate epiphytes of seagrass leaves

The growth and degeneration of the hydroid Sertularia perpusilla, an obligate epiphyte of leaves of the seagrass Posidonia oceanica

The hydrorhizae of Sertularia perpusilla colonies that originate from stolon attachments initially grow up and down Posidonia leaves. After a short time the distal hydroid tissue degenerates concurrently with the downward growth of the proximal hydrorhiza onto younger sections of the leaves. Consequently the hydroids ‘move’ down the leaves which grow upward from a basal meristem. In situ inversion of leaves had no effect on either the orientation or the rates of growth and degeneration. This indicates that orientation may be in response to age related features of leaf tissue rather than to light, gravity or water movement, the directions of which were reversed by inverting the leaves. However, orientation of growth of new hydroids from attached stolons is immediate, probably before the hydroid colony is long enough to be able to detect an age gradient. This paradox could be explained if initial orientation were based on the direction of gravity or light but subsequent growth were directed along the age gradient. For hydroids in the size range studied there was a relation between growth rate and number of hydranths. Thus growth rate may be limited by food rather than by there being only one growing tip of the hydrorhizae.

THE RED ALGAL EPIPHYTES MICROCLADIA COULTERI AND M. CALIFORNICA (RHODOPHYCEAE, CERAMIACEAE). I. TAXONOMY, LIFE HISTORY AND PHENOLOGY1

ABSTRACTIn the northeast Pa@, there are two epiphytic species of the genus Microcladia Grev. Microcladia coulteri Ham. grows on a wide range of red algal and occasionally brown algal basiphytes whereas M. californica Farl. grows only on the brown alga Egregia menziesii (Turn.) Aresch. Although both are obligate epiphytes in the field, they complete their life history in culture in the absence of their respective basiphytes. Along the coast of central California, M. californica exhibits distinct seasonal patterns in reproduction whereas M. coulteri does not. In addition to previously documented daferences in cystocarp development and branchlet patterns, the two taxa can be delineated by differences in spore sizes, timing of spore attachment and morphology of the primary rhizoid. The haploid chromosome number for both species ranges from 14‐16. Attempts to hybridize the two species have been unsuccessful. In addition, restriction fragment length polymorphism analyses of the plastid DNA of the two species provides further evidence that Microcladia coulteri and Microcladia californica represent distinctive species.

The Epiphytic Lichens of Greenland

One hundred and six species of epiphytic lichens are reported from Greenland; 11 species previously reported as epiphytes from that country could not be confirmed; 56 of the species are obligate or common epiphytes, 28 are normally found on soil, mosses, etc., while 22 species are normally found on rock substrates. Twelve species are reported from Greenland for the first time. Greenland is normally believed to have arctic climate preventing tree growth. Never- theless, protected areas in the continental parts of South and West Greenland have tem- peratures above 10'C in July, and small woods with trees up to 6 m high are found in such areas. South of 62'N, Betula pubescens is the dominant tree; between 62' and 66?N Alnus crispa dominates the scrubs, and, north of that area, Salix glauca forms impressive thick- ets. The knowledge of the epiphytic lichen flora mainly dates from the works of Branth and Grcnlund (1887) and Branth (1892, 1895). A few epiphytic lichens have been reported also in later works from Southwest Greenland (Dahl 1950; Hansen 1971; Hansen 1978). It is the aim of this work to give an enumeration of the epiphytic lichens based on literature and on new collections. The greater part of the new material was collected by myself in the years 1974-1980. Smaller undetermined collections were placed at my dis- posal by Bent Fredskild, Peter Fries Moller and Kim Pilegaard, and M. Skytte Christiansen allowed me to publish his determined collections from an Alnus crispa locality in South Greenland. Earlier reports of species not found in the above mentioned collections have been checked if possible and placed under their current names. Reports that could not be checked are listed in brackets under the name, including author citations, used in the original report. Species new to Greenland are marked with an asterisk. The new material, and the older material collected by other Danes have been deposited at the Botanical Museum of Copenhagen (c), while Dahl's and Lynge's collections are found in Oslo (o), eventually with duplicates in c. The localities (see map, Fig. 1) are as follows: 1. Head of Kangerdluarssuk, 60'52'N, 45'50'S. Thickets of Betula pubescens 1-2 m high with associated Salix glauca and Sorbus groenlandica. Juniperus communis, Betula glandulosa and Rhododendron lapponicum present as single shrubs.

PHOTOSYNTHESIS AND TRANSLOCATION STUDIES OF LAURENCIA SPECTABILIS AND ITS SYMBIONT JANCZEWSKIA GARDNERI (RHODOPHYCEAE)1,2

ABSTRACTThe symbiotic association between the supposed parasite Janczewskia gardneri Setchell & Guernsey and its host Laurencia spectabilis Postels & Ruprecht was investigated. Mature plants of J. gardneri were pigmented, contained “typical” red algal chloroplasts when viewed by electron microscopy, and were capable of photosynthesis. Both J. gardneri and L. spectabilis incorporated 14C‐label from NaH14CO3 into similar compounds, including sugars (floridoside, isofloridoside, galactose, glucose) and amino acids (alanine, aspartic acid, glutamic acid, glycine, serine). Translocation of 14C‐labeled photosynthetic products between mature J. gardneri and its host did not occur. This research suggests that mature individuals of J. gardneri are obligate epiphytes.

Microconidial Dimorphism in the Lichen Genus Parmelia

The first microconidial dimorphism in noncrustose lichen-forming fungi to have ecogeographical correlations is reported from two North American species. The microconidia of Parmelia hypoleucites and those of the new species P. semansiana differ in length, the former averaging about twice (11-12 gm) as long as the latter (5 gm). Parmelia hypoleucites, apparently an obligate epiphyte of trees, is confined to the highlands of Mexico and Arizona. Parmelia semansiana, primarily a rock-inhabiting species that extends its substrate tolerance to bark at the center of its range, is widely distributed in south-central North America. Small but significant spore-size differences accompany the microconidial dimorphism.

Microconidial Dimorphism in the Lichen Genus Parmelia

SUMMARYThe first microconidial dimorphism in noncrustose lichen-forming fungi to have ecogeographical correlations is reported from two North American species. The microconidia of Parmelia hypoleucites and those of the new species P. semansiana differ in length, the former averaging about twice (11-12 μm) as long as the latter (5 μm). Parmelia hypoleucites, apparently an obligate epiphyte of trees, is confined to the highlands of Mexico and Arizona. Parmelia semansiana, primarily a rock-inhabiting species that extends its substrate tolerance to bark at the center of its range, is widely distributed in south-central North America. Small but significant spore-size differences accompany the microconidial dimorphism.

Studies on the association between Noteia anomala and Hormosira banksii (Phaeophyta)

Anatomical, ultrastructural, ecological and physiological aspects of the relationship between the common brown alga, Hormosira banksii, and the obligate epiphyte Notheia anomala are described. The highest frequencies of infection by N. anomala occur in sexually mature H. banksii in tide-pool populations. Male and female H. banksii are equally affected, and the most common sites of infection are the receptacles where N. anomala attaches around the ostiole rather than within the conceptacle. Prolonged culture of N. anomala was only possible with media containing a filtered extract of the receptacles of the host species. Light and electron microscopy of the regions of thallus connecting N. anomala and H. banksii showed a wedge-shaped incursion of N. anomala in the H. banksii thallus, and very close contact between the adjacent cell walls of host and epiphyte, but there were no protoplasmic connections. The biological significance of the relationship between N. anomala and H. banksii is discussed.

“OBLIGATE” ALGAL EPIPHYTE: SMITHORA NAIADUM GROWS ON A SYNTHETIC SUBSTRATE1

SUMMARYThe supposedly obligate epiphyte Smithora naiadum, normally found only on the sea grasses Phyllospadix scouleri and Zostera marina, grew on an artificial substrate under field conditions. This development shows that the alga does not appear to require a chemical factor from its normal host plant for (1) substrate selection and adhesion, (2) growth of basal cushion and young blades, or (3) maturation of thick cushions.

Alternation of Generations in Ectocarpus siliculosus

1. An alternation of generations occurs in the life cycle of Ectocarpus siliculosus growing in the region of Woods Hole. 2. The diploid asexual plants bear unilocular and plurilocular sporangia on separate individuals or simultaneously on the same individual. In the plurilocular sporangium are formed diploid zoo-spores which germinate directly into other asexual plants. 3. A reduction division occurs in the unilocular sporangium and the haploid zoids formed in this organ germinate into haploid sexual plants. 4. The sexual plants are dioecious and produce physiologically anisogamous gametes in plurilocular sporangia. The zygotes develop into diploid asexual plants. 5. The sexual generation propagates itself by the parthenogenetic development of about 5 per cent of the unfused gametes of either sex. 6. Haploid plants are inferior to diploid plants in stature, size of cells, and size of plurilocular sporangia. 7. Plants were grown in suspended drops from spore to spore. Some cultures lived for more than six months. 8. Sexual plants were found only at Penikese Island where they occur on Chordaria. Asexual plants are widely distributed in the region of Woods Hole and occur on Chorda, Chordaria, and Spartina. 9. It is suggested that the sexual plants are obligate epiphytes on Chordaria and that their absence at Woods Hole proper is owing to the absence of this host in this locality.