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.

Floral traits, pollination ecology and breeding system of three Clematis species (Ranunculaceae) in Yunnan province, southwestern China

2010 ◽  
Vol 58 (2) ◽  
pp. 115 ◽  
Author(s):  
Nan Jiang ◽  
Wen-Bin Yu ◽  
Hong-Zhe Li ◽  
Kai-Yun Guan
Keyword(s):  
Inbreeding Depression ◽  
Breeding System ◽  
Pollen Limitation ◽  
Mating Strategies ◽  
Breeding Systems ◽  
Floral Traits ◽  
Pollination Syndrome ◽  
Self Pollination ◽  
Hand Pollination ◽  
Integrative Study

Flowers of Clematis display showy corollas and diversified shapes. This diversity motivates study of adaptive evolution of flower–pollinator interactions and the functional association between floral traits and plant mating strategies. An integrative study was undertaken, which focused on pollination and reproductive biology of three species representing all three floral types of Clematis. Floral traits were measured, and pollinator assemblages were observed in the field. Bagging, hand-pollination and removal treatments were used to examine breeding systems. The inbreeding depression and pollen limitation were estimated by fruit-set and seed production obtained from pollination treatments. Their floral traits are distinctly different, but are highly associated with pollination syndrome and breeding system. Among them, Clematis akebioides and C. rehderiana may be facultative autogamy (the former was delayed selfing, and the later competing selfing), and C. chrysocoma may be nearly obligate outcrossing. These conclusions are reflected in their stamen-pistil ratios. The levels of inbreeding depression are negatively associated with autonomous self-pollination. Evolution of self-pollination in C. akebioides and C. rehderiana, and pollen limitation in reproduction of the three Clematis species are discussed. This present study, integrating with previous results, will help us to comprehensively recognise and understand the pollination system and reproductive characteristics of Clematis.

scholarly journals Comparative floral ecology and breeding systems between sympatric populations of Nothoscordum bivalve and Allium stellatum (Amaryllidaceae)

2020 ◽  
Vol 26 ◽  
Author(s):  
Daniel S Weiherer ◽  
Kayla Eckardt ◽  
Peter Bernhardt
Keyword(s):  
Fruit Set ◽  
Seed Set ◽  
Geometric Mean ◽  
Floral Biology ◽  
Breeding Systems ◽  
Outbreeding Depression ◽  
Sympatric Populations ◽  
Closely Related Species ◽  
Floral Ecology ◽  
Self Pollination

We compared the floral biology of two sympatric populations of closely related species over two seasons. In 2018, Nothoscordum bivalve (L.) Britton bloomed from April 23 to May 7 and Allium stellatum Nutt. Ex Ker Gawl bloomed from August 28 to October 4. Erect, white flowers of N. bivalve were scented and had septal nectaries. Erect, pink-purple flowers of A. stellatum had septal nectaries, no discernible scent, and a style that lengthened over the floral lifespan. Both species were pollinated by bees with the most common geometric mean of body dimensions between 2-3 mm. Most bees carried pure loads of the host plant’s pollen. Despite phenological isolation, the two herbs shared three bee species. Allium stellatum was also pollinated by the beetle Chauliognathus pensylvanicus DeGeer (Cantharidae). Tepal nyctinasty ensured mechanical self-pollination in N. bivalve. Protandry occurred in A. stellatum. In N. bivalve, the proportion of pollen tubes penetrating ovules was highest in bagged, self-pollinating flowers. However, in A. stellatum it was highest in exposed flowers and hand cross-pollinated flowers. Fruit set in N. bivalve was highest in exposed and bagged, self-pollinating flowers. In A. stellatum, fruit set was highest in both exposed and hand cross-pollinated flowers. Seed set was the same among all treatments for both species. We interpret these results as evidence that A. stellatum is a self-incompatible, obligate outcrosser. Nothoscodum bivalve is a self-compatible, obligate inbreeder employing mechanical and insect-mediated self-pollination. Outbreeding depression appears to occur in N. bivalve with a partial trend towards intraspecific cross-incompatibility.

scholarly journals Self-incompatibility and Time of Stigma Receptivity in Two Species of Hydrangea

HortScience ◽  
2004 ◽  
Vol 39 (2) ◽  
pp. 312-315 ◽  
Author(s):  
Sandra M. Reed
Keyword(s):  
Seed Set ◽  
Pollen Tubes ◽  
Tube Length ◽  
Self Incompatibility ◽  
Stigma Receptivity ◽  
Self Pollination ◽  
Incompatibility System ◽  
Self Compatibility ◽  
Days After Anthesis ◽  
Pollen Tube Length

The objectives of this study were to evaluate self-incompatibility in Hydrangea paniculata Sieb. and H. quercifolia Bartr. and to determine optimum time for pollination of these two species. Flowers from three genotypes of each species were collected 1, 2, 4, 8, 24, 48, and 72 hours after cross- and self-pollination, stained with aniline blue and observed using a fluorescence microscope. In both species, pollen germination was observed on stigmas of over half of the flowers collected 4 to 72 hours after cross- or self-pollination. Differences in pollen tube length between cross- and self-pollinated flowers were noted from 8 to 72 hours after pollination in H. paniculata and from 24 to 72 hours after pollination in H. quercifolia. By 72 hours after pollination, most self-pollen tubes had only penetrated the top third of the style but cross-pollen tubes had grown to the base of the style and entered 40% to 60% of the ovules. Stigmas of H. paniculata were receptive to pollen from anthesis to 5 days after anthesis, while stigmas of H. quercifolia were receptive from 1 to 5 days after anthesis. This study provides evidence of a gametophytic self-incompatibility system in H. paniculata and H. quercifolia. Occasional self-seed set previously observed in these species was theorized to have been due to pseudo-self compatibility.

Breeding system of Tristerix corymbosus (Loranthaceae), a winter-flowering mistletoe from the southern Andes

2005 ◽  
Vol 53 (4) ◽  
pp. 357 ◽  
Author(s):  
Marcelo A. Aizen
Keyword(s):  
Reproductive Success ◽  
Breeding System ◽  
Seed Set ◽  
Breeding Systems ◽  
Southern Andes ◽  
Flower Pollination ◽  
Hand Pollination ◽  
Pollinator Service ◽  
Sephanoides Sephaniodes ◽  
Tristerix Corymbosus

Harsh climates should select for breeding systems that uncouple reproductive success from unpredictable pollinator service, such as autonomous, within-flower pollination and autogamous seed set. I assessed the breeding system and overall pollinator dependence of Tristerix corymbosus (L.) Kuijt, a mistletoe that blooms during the snowy winters of the southern Andes and whose flowers are visited by the hummingbird Sephanoides sephaniodes. The nectar produced by T. corymbosus represents the main food for overwintering populations of S. sephanioides, one of the principal pollinators in the temperate forest of southern South America. Hand-pollination experiments showed that this plant is fully self-compatible, with only a slight advantage of cross- over self-pollen during either germination or early tube growth. Despite self-compatibility, T. corymbosus exhibited a limited capacity for autonomous, within-flower pollination and high dependence on its hummingbird pollinator for full seed set. Thus, dwindling hummingbird populations should compromise reproductive success in this potential keystone plant species.

Monoecious Nitella species (Characeae, Charophyta) from south-eastern mainland Australia, including Nitella paludigena sp. nov.

2008 ◽  
Vol 21 (3) ◽  
pp. 201 ◽  
Author(s):  
Michelle T. Casanova ◽  
Kenneth G. Karol
Keyword(s):  
South Australia ◽  
The South ◽  
Tea Tree ◽  
Australian Species ◽  
South Eastern ◽  
South West

Identification of Australian species of Nitella is problematic. Several species of monoecious Nitella have been described from south-eastern mainland Australia, but identification of these based on current treatments has been difficult. In response to the discovery of a new monoecious Nitella from the swamps of the Fleurieu Peninsula in South Australia, the monoecious species of Nitella from south-eastern mainland Australia were examined and compared. N. paludigena M.T.Casanova & K.G.Karol is distinguished from other monoecious species on the basis of its overall vegetative morphology and oospore morphology. N. paludigena is found in peaty tea-tree (Leptospermum sp) swamps on the Fleurieu Peninsula in South Australia, and in the south-west of Victoria. A description of the morphology and ecology of the five monoecious Nitella species from south-eastern mainland Australia is given, along with a key.

Middle and Late Iron Age Occupation at Cadnam Farm, Alton, Hampshire

2018 ◽  
Vol 73 (1) ◽  
pp. 110-136
Author(s):  
Oliver Good ◽  
Richard Massey
Keyword(s):  
Iron Age ◽  
The South ◽  
Late Iron Age ◽  
South West ◽  
Middle Iron Age

Three individual areas, totalling 0.55ha, were excavated at the Cadnam Farm site, following evaluation. Area 1 contained a D-shaped enclosure of Middle Iron Age date, associated with the remains of a roundhouse, and a ditched drove-way. Other features included refuse pits, a four-post structure and a small post-built structure of circular plan. Area 2 contained the superimposed foundation gullies of two Middle Iron Age roundhouses, adjacent to a probable third example. Area 3 contained a small number of Middle Iron Age pits, together with undated, post-built structures of probable Middle Iron Age date, including a roundhouse and four and six-post structures. Two large boundary ditches extended from the south-west corner of Area 3, and were interpreted as the funnelled entrance of a drove-way. These contained both domestic and industrial refuse of the late Iron Age date in their fills.

Sign in / Sign up

Export Citation Format

Share Document