Mode of Pollination and Floral Sexuality in Thalictrum

Kaplan, Stuart M.; Mulcahy, David L.

doi:10.2307/2406946

Cited by 54 publications

(58 citation statements)

References 15 publications

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“…In an initial study by Kaplan and Mulcahy (1971), females enclosed in bridal veil, to exclude pollination by insects but not wind, were still able to set seed at slightly less than half the rate of unenclosed control females. The results of this paper support their findings that wind contributes substantially to pollination (Fig.…”

Section: Discussionmentioning

confidence: 97%

“…Sepals are white, relatively small compared to the stamens and pistils, and fall off soon after the flower matures. The species is partially wind-pollinated (Boivin 1944;Kaplan and Mulcahy 1971), with the primary insect visitors being Syrphid flies. Because of these characteristics, Thalictrum species provide an excellent system with which to explore the evolution of cryptic dioecy and its maintenance.…”

Section: Study Organismmentioning

confidence: 99%

“…Because the focus of studies on cryptic dioecy until now has been on the pollinator-attraction hypothesis, researchers have primarily investigated the pollination biology of such species (Kaplan and Mulcahy 1971;Clay and Ellstrand 1981;Kevan and Lack 1985;Kevan et al , 1990Schlessman et al 1990;Hoffman 1992) and ignored the role of the latter two hypotheses. Since most cryptically dioecious species are morphologically androdioecious (having male individuals that produce staminate flowers and female individuals that produce apparently perfect flowers) with pollen as the main food reward for pollinators (Mayer and Charlesworth 1991), the pollinator-attraction hypothesis is an appealing explanation for the maintenance of this breeding system.…”

Section: Introductionmentioning

confidence: 99%

“…Females of this species produce fullsize stamens which contain sterile pollen that lack germination pores. Therefore, T. pubescens, like the majority of cryptically dioecious species, is functionally dioecious but appears androdioecious (Kaplan and Mulcahy 1971). This is a particularly interesting species in which to study the factors maintaining cryptic dioecy, since T. pubescens is at least partially pollinated by wind (Kaplan and Mulcahy 1971;Melampy and Hayworth 1980) and may not need the sterile stamens for successful fertilization.…”

Section: Introductionmentioning

confidence: 99%

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Stamens are not essential as an attractant for pollinators in females of cryptically dioecious Thalictrum pubescens Pursch. (Ranunculaceae)

Davis

1997

Sexual Plant Reproduction

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It has been hypothesized that females of some dioecious species maintain stamens that produce sterile pollen as a means of attracting pollinators to promote greater seed set. However, this hypothesis has rarely been tested. This paper examines the role of pollinators in the maintenance of sterile stamens in the cryptically dioecious species, Thalictrum pubescens. Wind was found to contribute to pollination; branches of female T. pubescens enclosed in cheesecloth to exclude insects but not wind were still able to set seed. Therefore, females may not need the stamens for pollination. In 1994, insects were found to discriminate against emasculated female flowers, but this discrimination did not lead to a significant difference in either the amount of pollen received or seed set. In 1995, emasculation was combined with the addition of pollen to determine if emasculated females were pollen limited. No significant effect of pollen addition or emasculation was found. Emasculated branches in the pollen-addition treatment appeared to have slightly lower seed set than non-emasculated branches that received pollen, indicating that the slight reduction in seed set was caused by emasculation rather than pollen limitation. Since stamens do not appear to be maintained as pollinator attractants, other explanations, such as genetic constraints, must be investigated.

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Section: Discussionmentioning

confidence: 97%

Section: Study Organismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Stamens are not essential as an attractant for pollinators in females of cryptically dioecious Thalictrum pubescens Pursch. (Ranunculaceae)

Davis

1997

Sexual Plant Reproduction

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“…299-324) stated that the adaptation to anemophily is likely responsible for the evolution of imperfect, monoecious, and dioecious flowers, made possible through the reduction of perianth parts (inconspicuousness) and the separation of sexes. Indeed, positive relationships have been documented between anemophily and dioecy in flowering plants (Kaplan and Mulcahy 1971;Freeman et al 1980aFreeman et al , 1980bMuenchow 1987;Steiner 1988;Vamosi and Vamosi 2014). Environmental conditions that allow for anemophily include clumped distributions of plants, definitive physical cues (seasonality to diel periodicities in microclimate), and opportunities for pollen to move rapidly (Whitehead 1983;Culley et al 2002;Montoya-Pfeiffer et al 2016).…”

Section: Degress Latitudementioning

confidence: 99%

High Incidence and Correlates of Dioecy in the Flora of the Canadian Arctic Archipelago

Kevan¹,

Godglick

2017

Arctic Science

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In comparing the incidence of dioecy in North American floras, we report a strong, positive correlation with increasing latitude. Dioecy in the High Arctic is highly correlated with woodiness, as elsewhere. It is significantly correlated with fleshy, zoochorous fruits as well documented elsewhere. Correlation with floral inconspicuousness, which we define in terms of attractiveness to pollinators (i.e., functionality to pollination), is weak and statistically insignificant. Published findings on that correlation are equivocal; different authors variously defined inconspicuousness in ways that may or may not reflect functionality in pollination. Although we acknowledge that for some diverse taxa (e.g., Salix spp.) the relative importances of anemophily, zoophily (entomophily), and ambophily are unknown, we assigned species to (a) anemophily if evidence for entomophily could not be invoked and (b) entomophily if insect pollination was considered possible (i.e., counts for entomophily include possibly ambophilous species). We found no correlation between dioecy and anemophily/entomophily. The view that insularity favours establishment of dioecious taxa may be invoked by considering localized and disjoint post-glacial colonization. The view that dioecy, as a form of xenogamy, has evolved in response to offsetting the adverse consequences of inbreeding and accumulation of mutations may apply under High Arctic conditions, further eroding ideas that short, harsh, active seasons promote self-fertilization (autogamy), agamospermy, and vegetative reproduction while disfavouring xenogamy by insect or wind pollination.Key words: plant sexual reproduction, latitudinal gradient, pollination, anemophily, floral characters, fleshy fruit, woodiness.Résumé : En comparant l'incidence de dioécie chez les flores nord-américaines, nous constatons une corrélation positive étroite avec une latitude croissante. La dioécie dans le Haut-Arctique est hautement corrélée avec la lignification, comme ailleurs. Elle est significativement corrélée avec les fruits charnus, « zoochorous », aussi documentés ailleurs. La corrélation avec l'aspect discret floral, que nous définissons en matière d'attrait aux pollinisateurs (c.-à-d. la fonctionnalité à la pollinisation), est faible et statistiquement sans importance. Les conclusions publiées sur cette corrélation sont ambiguës; les différents auteurs ont défini l'aspect discret de différentes façons qui peuvent ou ne peuvent pas refléter la fonctionnalité à la pollinisation. Bien que nous reconnaissions que pour certains taxa (p. e. Salix spp.) les importances relatives de la pollinisation anémophile, zoophile (entomophile) et ambophile (par le vent et les insectes) sont inconnues, nous avons assigné des espèces à (a) l'anémophilie si la preuve de l'entomophilie ne pouvait pas être invoquée et à (b) l'entomophilie si la pollinisation d'insecte a été considérée possible (c.-à-d. les dénombrements pour entomophilie comprennent possiblement les espèces ambophiles). Nous n'avons trouvé aucune c...

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Influence of local density and sex ratio on pollination in an ambophilous flowering plant

Timerman

Barrett

2020

American J of Botany

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Citation: Timerman, D., and S. C. H. Barrett. 2020. Influence of local density and sex ratio on pollination in an ambophilous flowering plant.PREMISE: Variation in local density and sex ratio in dioecious plants can affect mating success through the actions of pollen vectors, principally generalist insects or wind. Increased density and male-biased sex ratios should promote pollen transfer and seed production, but their combined effects have not been investigated for ambophilous species, which exhibit both insect and wind pollination. METHODS:We manipulated density (low vs. high) and sex ratio (1:1 vs. 3:1 male-biased) in arrays of dioecious ambophilous Thalictrum pubescens. We quantified visitation rates and foraging times to examine whether pollinators exhibited sex-specific preferences and determined the seed set of arrays. RESULTS:Pollinators visited more plants per foraging bout at high than low density. Visitation rates and foraging times of visitors were greater for male than for female plants but did not depend on the density or sex ratio of arrays. However, whereas solitary bees displayed a strong preference for males, hover flies were indifferent to plant sex phenotype. Solitary bees also visited significantly more plants per foraging bout than hover flies. There was a significant interaction between density and sex ratio on seed set. At low density, seed set was greater for 3:1 than for 1:1 arrays, but at high density the opposite pattern occurred. CONCLUSIONS:The demographic factors we investigated had complex influences on pollinator foraging behavior and patterns of seed set. Several factors may explain our results, including the influence of density and sex ratio on pollen export from arrays, grooming by pollinators, and the contribution of wind pollination.

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Mode of Pollination and Floral Sexuality in Thalictrum

Cited by 54 publications

References 15 publications

Stamens are not essential as an attractant for pollinators in females of cryptically dioecious Thalictrum pubescens Pursch. (Ranunculaceae)

Stamens are not essential as an attractant for pollinators in females of cryptically dioecious Thalictrum pubescens Pursch. (Ranunculaceae)

High Incidence and Correlates of Dioecy in the Flora of the Canadian Arctic Archipelago

Influence of local density and sex ratio on pollination in an ambophilous flowering plant

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