Gametophyte morphology and reproductive biology in Elaphoglossum

1998 ◽  
Vol 76 (11) ◽  
pp. 1967-1977 ◽  
Author(s):  
Wen-Liang Chiou ◽  
Donald R Farrar ◽  
Tom A Ranker
Keyword(s):  
Life Span ◽  
Reproductive Biology ◽  
Breeding System ◽  
Growth Habit ◽  
Agar Medium ◽  
Genetic Load ◽  
Fern Gametophyte ◽  
Fixed Heterozygosity ◽  
Naturally Occurring ◽  
Close Relationship

Gametophyte morphology, behavior, and growth habit of Elaphoglossum alatum Gaud., Elaphoglossum callifolium (Bl.) Moore, Elaphoglossum crassifolium (Gaud.) Anderson & Crosby, Elaphoglossum marginatum (Wall ex Fee) Moore, and Elaphoglossum yoshinage (Yatabe) Makino were observed on artificial agar medium. The morphology of these gametophytes are very different from those of Bolbitis, a genus of Lomariopsidaecae thought to have a close relationship with Elaphoglossum. The growth habit of Elaphoglossum gametophytes, like many other epiphytic species, is perennial and clone forming. Isozyme analysis of naturally occurring sporophytes of E. alatum, E. crassifolium, and Elaphoglossum paleaceum (Hook. & Grev.) Sledge suggest that sporophytes of E. alatum and E. crassifolium are diploid and derived from highly outbreeding populations. Fixed heterozygosity in E. paleaceum suggests that sporophytes of this species are polyploid, but at least some outcrossing occurs. High genetic loads determined from single gametophyte cultures of E. callifolium and E. crassifolium indicate low probabilities of successful intragametophytic selfing. Several tests indicate, however, that these species neither produce nor respond to antheridiogens. Therefore, intergametophytic mating in these species is likely maintained by genetic load. This mating behavior is promoted by a perennial and clone-forming growth habit which may function to prolong the life-span and to enlarge the space occupied by individual gametophytes.Key words: Elaphoglossum, fern gametophyte, reproductive biology, breeding system.

Spontaneous Lesions in Chinese Hamsters

1977 ◽  
Vol 14 (5) ◽  
pp. 449-462 ◽  
Author(s):  
S. A. Benjamin ◽  
A. L. Brooks
Keyword(s):  
Bone Marrow ◽  
Life Span ◽  
Biomedical Research ◽  
Myelogenous Leukemia ◽  
Cricetulus Griseus ◽  
Naturally Occurring ◽  
Chinese Hamsters ◽  
Nodular Hyperplasia ◽  
Long Life ◽  
Pulmonary Granulomas

One hundred and fifty-seven Chinese hamsters ( Cricetulus griseus) from the Lovelace Foundation Inhalation Toxicology Research Institute colony had pulmonary granulomas, nodular hyperplasia of the liver, granulocytic bone marrow hyperplasias and myelogenous leukemia, nephrosclerosis and uterine adenocarcinomas. These Chinese hamsters had a median life span of 1 075 days. The long life span and information on naturally-occurring diseases suggest that this species might be more widely used for toxicological and biomedical research.

scholarly journals Hymenasplenium volubile: documentation of its gametophytes and the first record of a hemiepiphyte in the Aspleniaceae

2019 ◽  
Vol 124 (5) ◽  
pp. 829-835
Author(s):  
Jacob L Watts ◽  
Robbin C Moran ◽  
James E Watkins
Keyword(s):  
New World ◽  
Growth Form ◽  
Growth Habit ◽  
Microscopic Analysis ◽  
First Record ◽  
Laboratory Studies ◽  
Lower Margin ◽  
Fern Gametophyte ◽  
Gametophyte Ecology ◽  
Field Setting

Abstract Background and Aims Through careful field examination of the growth habit of the gametophytes and sporophytes of Hymenasplenium volubile across an ontogenetic series, we aim to understand better the evolution of epiphytism in this poorly understood group of ferns Methods We made field observations of H. volubile sporophytes and gametophytes, and brought specimens back to the lab for microscopic analysis. In the field, sporophytes at each ontogenetic stage were photographed to document the species’ growth habit. We used an existing phylogeny to optimize growth form of New World Hymenasplenium. Key Results Young sporophytes were at first fully epiphytic and produced one or two long feeding roots that extend to the soil where they branch profusely. The feeding roots remain in contact with the soil throughout the life of the plant. Thus, H. volubile is a hemiepiphyte. While immature, gametophytes are appressed to the tree trunk, but, as their gametangia mature, their lower margin lifts upward, imparting a shelf-like appearance to the thallus. The thallus attaches to the substrate by branched rhizoids produced along the margin of the thallus in contact with the substrate. Conclusions Hemiepiphytes are a key link in the evolution of epiphytic ferns and may act as a bridge between the forest floor and the canopy. Our finding is the first report of hemiepiphytism in Aspleniaceae, a large lineage with many epiphytic and terrestrial taxa. This work serves as an important model to understand the evolution of epiphytism in this group specifically and in ferns in general. The majority of our understanding of fern gametophyte biology is derived from laboratory studies. Our efforts represent a fundamental contribution to understanding fern gametophyte ecology in a field setting.

Kanakomyrtus (Myrtaceae): A New Endemic Genus from New Caledonia with Linear Stigma Lobes and Baccate Fruits

2009 ◽  
Vol 34 (2) ◽  
pp. 330-344 ◽  
Author(s):  
Neil Snow
Keyword(s):  
New Species ◽  
Reproductive Biology ◽  
New Caledonia ◽  
Field Work ◽  
Windward Side ◽  
Generic Type ◽  
Distribution Maps ◽  
Close Relationship ◽  
Unisexual Flowers ◽  
Species Descriptions

Kanakomyrtus (Myrtaceae) is a newly described genus endemic to New Caledonia. Kanakomyrtus myrtopsidoides, the generic type, is transferred from Eugenia. Five new species are described: K. mcphersonii, K. revoluta, K. dawsoniana, K. prominens, and K. longipetiolata. The genus occurs in forests at elevations between 500–1,600 m on the relatively mesic windward side of the Grande Terre. It is distinct from other baccate genera of Myrtaceae by a combination of linear stylar lobes, densely glandular stamens and stigmas, and a short but densely hoary indumentum that is brownish when dry. The thinly membranous partitions that partially extend between the seeds of some species suggest a close relationship to Archirhodomyrtus and some species traditionally placed in Rhodomyrtus and Octamyrtus. Four of the six species have unisexual flowers, but much additional field work is needed to assess the reproductive biology of the genus. Following IUCN guidelines, four species are proposed as either Endangered or Critically Endangered, whereas the remaining species are considered Vulnerable and of Low Concern. Species descriptions, illustrations, distribution maps, and keys to species of the genus and related taxa of baccate Myrtaceae from New Caledonia are included.

The Breeding Systems of Stylidium graminifolium and Stylidium productum (Stylidiaceae)

1990 ◽  
Vol 38 (2) ◽  
pp. 217 ◽  
Author(s):  
AJ Willis ◽  
JE Ash
Keyword(s):  
Breeding System ◽  
Seed Set ◽  
Breeding Systems ◽  
The South ◽  
Pollination Experiments ◽  
Australian Species ◽  
South West ◽  
Self Pollination ◽  
Incompatibility System ◽  
Close Relationship

The breeding systems of Stylidiurn grarninifolium and S. producturn (= S. grarninifoliurn var. caulescens) were studied by observing the phenology of individual flowers and inflorescences, and relating the data to a series of pollination experiments within and between the species. Inter-specific pollinations yielded similar levels of seed-set to crosses within the species indicating a close relationship between the taxa. Self-pollination of either species is uncommon; however, when it occurs, the majority of selfed ovules are aborted post-zygotically, probably by a system of recessive lethals, as there is no indication of an incompatibility system. It is concluded that the breeding systems of S. grarninifoliurn and S. productum, two of the few eastern Australian species, are similar to those of many Stylidiurn species from the south-west, casting doubt upon hypotheses that the breeding system has led to high rates of speciation in the south-west.

THE BIOLOGY OF CANADIAN WEEDS.: 53. Convolvulus arvensis L.

1982 ◽  
Vol 62 (2) ◽  
pp. 461-472 ◽  
Author(s):  
SUSAN E. WEAVER ◽  
WALKER R. RILEY
Keyword(s):  
Reproductive Biology ◽  
Prince Edward Island ◽  
Growth Habit ◽  
Convolvulus Arvensis ◽  
Field Bindweed ◽  
Agricultural Regions ◽  
Rhizome System ◽  
Methods Of Control

Convolvulus arvensis L., field bindweed, is an introduced weed which occurs in the agricultural regions of all provinces of Canada with the exception of Newfoundland and Prince Edward Island. Its twining growth habit and extensive root and rhizome system make it exceptionally difficult to control. It spreads by both seeds and root or rhizome fragments. Details of its morphology, reproductive biology, response to parasites, and methods of control are presented.

A SELECTIVE PLATING AGAR FOR DIRECT ENUMERATION OF SALMONELLA IN ARTIFICIALLY CONTAMINATED DAIRY PRODUCTS1

1974 ◽  
Vol 37 (8) ◽  
pp. 441-444 ◽  
Author(s):  
R. H. Reamer ◽  
R. E. Hargrove ◽  
F. E. McDonough
Keyword(s):  
Dairy Products ◽  
Agar Medium ◽  
Cottage Cheese ◽  
Selective Agent ◽  
Surrounding Area ◽  
Observable Effect ◽  
Naturally Occurring ◽  
Dry Milk ◽  
Colony Color ◽  
Selective Plating

A selective plating medium was developed that allows direct enumeration of salmonellae in dairy products such as nonfat dry milk, and Cheddar and cottage cheese. The agar medium developed was a modification of the Lysine-Iron-Cystine broth of Hargrove et al., 1971. Strains of species of the genera Escherichia, Enterobacter, Citrobacter, Proteus, Shigella, Pseudomonas, and Bacillus were easily differentiated from salmonellae by colony color and color of surrounding area or absence of growth. The antibiotic, novobiocin, used as a selective agent, inhibited growth of some Proteus, Shigella, and Escherichia; however the antibiotic was most effective against Bacillus, without having any observable effect on salmonellae. The medium was sufficiently sensitive and selective to permit detection of as few as 1–2 salmonellae per gram of product in the presence of naturally occurring bacteria and should be of considerable value in following the Salmonella content of artificially contaminated foods during processing and also during storage.

Evolution and biogeography ofLyalliaandHectorella(Portulacaceae), geographically isolated sisters from the Southern Hemisphere

2007 ◽  
Vol 19 (4) ◽  
pp. 417-426 ◽  
Author(s):  
Steven J. Wagstaff ◽  
Françoise Hennion
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Common Ancestor ◽  
Growth Habit ◽  
Intergenic Spacer ◽  
Plant Evolution ◽  
Late Tertiary ◽  
Close Relationship ◽  
Divergence Estimates ◽  
Transoceanic Dispersal

AbstractThe Southern Hemisphere contains many monotypic taxa, for which phylogenetic relationships are important to illuminate biogeographical history. The monotypic genusLyalliais endemic to the sub-Antarctic Iles Kerguelen. A close relationship with another monotypic taxon, the New Zealand endemicHectorella, was proposed. They share a dense cushion growth habit with small coriaceous leaves that lack stipules. The solitary flowers are bicarpellate with two sepals, 4–5 petals, 3–5 stamens and a bifid style. The fruit is an indehiscent capsule with 1–5 seeds. The flowers ofLyallia kerguelensisare hermaphroditic with four petals and three stamens whereas the flowers ofHectorella caespitosaare female, male or hermaphroditic, with five petals and five stamens.Lyallia kerguelensisis rare on Kerguelen, whereasHectorella caespitosais confined to the South Island of New Zealand. Our phylogenetic analysis oftrnK/matK intergenic spacer andrbcL sequences provides evidence supporting a close relationship betweenLyalliaandHectorella. The two species form a well-supported clade that is nested within the Portulacaceae. Divergence estimates suggest they shared a common ancestor during the late Tertiary long after the fragmentation of Gondwana. Such relationships underscore the importance of transoceanic dispersal and extinctions for plant evolution in the Southern Hemisphere.

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