Pollination in an understorey vine, <i>Smilax rotundifolia</i>, a threatened plant of the Carolinian forests in Canada

Kevan, Peter G.; Ambrose, John D.; Kemp, James R.

doi:10.1139/b91-318

Cited by 8 publications

(2 citation statements)

References 4 publications

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“…Such a pattern should prevent pollen from being disseminated completely to one floral visitor and promote more effective gene dispersal (Erbar and Leins, 1995). The aggregation of pollen in clumps by viscin is thought to prevent wind dispersal (Kevan et al, 1991).…”

Section: Discussionmentioning

confidence: 99%

Floral Morphology and Development in Georgia Plume, Elliottia racemosa (Ericaceae), a Rare Coastal Plain Endemic

Radcliffe¹,

Affolter²,

Wetzstein³

2010

J. Amer. Soc. Hort. Sci.

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Georgia plume (Elliottia racemosa) is a threatened woody plant endemic to the Coastal Plain region of Georgia in the southeastern United States. Seed set is low in most populations, and sexual recruitment has not been observed in recent times. The objective of this study was to describe the floral biology of georgia plume. which is fundamental information needed to develop an understanding of the causes for lack of sexual reproduction in natural populations. Floral development was characterized and morphological characteristics at key developmental stages ranging from small, unopened buds to open flowers with receptive stigmas were examined using light and scanning electron microscopy. Flowering is protandrous, and anthers dehisce releasing pollen within closed buds before stigmas are receptive. Pollen tetrads, aggregated by viscin strands, are presented on unreceptive stigmas when petals reflex. Receptive stigmas developed a raised and lobed central region with a clefted opening leading to a stylar canal containing exudate produced in secretory regions. Receptivity of the non-papillate stigma is indicated by the formation of an exudate droplet, which is formed within 1 day after flower opening. Pollen viability was low to moderate; tetrad germination ranged from 20% to 40% using in vitro germination assays indicating poor pollen quality and may contribute to lack of seed development in some populations. No developmental abnormalities in stigmas or styles were observed indicating other factors are responsible for lack of sexual recruitment in the wild.

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Section: Discussionmentioning

confidence: 99%

Floral Morphology and Development in Georgia Plume, Elliottia racemosa (Ericaceae), a Rare Coastal Plain Endemic

Radcliffe¹,

Affolter²,

Wetzstein³

2010

J. Amer. Soc. Hort. Sci.

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“…Recent ecological research on rare plant species has addressed the importance of a variety of ecological factors (Schemske et al 1994), including competitive interactions (Batty et al 1984, Gawler et al 1987, habitat requirements (Buchele et al 1989), and reproductive ecology (Mehrhoff 1983, Kevan et al 1991, Buchele et al 1992. Much of this research has focused on the impacts of ecological factors on just one or a few stages of a plant's life cycle, which falls short of projecting effects on population dynamics.…”

Section: Introductionmentioning

confidence: 99%

Population Matrix Models of Aeschynomene Virginica, a Rare Annual Plant: Implications for Conservation

Griffith

Forseth

2005

Ecological Applications

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Matrix models are valuable tools for comparing population growth rates (λ) in different environments. Life table response experiments (LTRE) can then be used to identify those life history stages that are most important to observed population growth rate differences. We used matrix models of population growth and LTREs to analyze the effects of standing vegetation and seed dispersal on the population growth rate of Aeschynomene virginica, a rare, tidal, wetland annual. We combined seedling establishment, seedling survival to adulthood, adult fecundity, winter seed survival, probability of seeds entering a seed bank, and seed dispersal rates to calculate the matrix elements in a matrix model. Experimental removal of other plant species from field plots increased A. virginica fecundity, seedling establishment, and survival. The magnitude of these changes doubled between 1998 and 1999. Removal of interspecific competitors from population patches of A. virginica explained 54% of the variability of λ, while environmental variation between 1998 and 1999 explained only 1%. An additional 9% of the variability in λ was explained by adding the interaction of interspecific removal and year to the regression. Sensitivities of λ to changes in lower‐level parameters varied over several orders of magnitude. Fecundity had the smallest sensitivity, while seedling establishment made the largest contribution to λ in 1998, and seedling survival to adulthood made the largest contribution in 1999. Simulations indicated that changes in seed dispersal would have small effects on λ. Eighty percent (1998) to 90% (1999) of the seeds produced in local patches growing without interspecific vegetation would have to disperse before patch population growth rates would become negative. Although seed dispersal had little impact on within‐patch population dynamics, it may make seeds available to establish populations in nearby, open habitat patches. In population patches with interspecific vegetation, 30 seeds per plant (1998) and 80 seeds per plant (1999) would have to be added before patch population growth rates were positive. The most efficacious treatment to increase population sizes of this rare plant would be creating disturbed patches and not adding seeds.

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Assessment of pollen viability in hand‐pollination experiments: a review

Stone

Thomson

Dent-Acosta

1995

American J of Botany

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Pollen viability is known to decline, sometimes rapidly, with age and exposure to environmental stresses. Because of the potential impact of nongenetic factors on the ability of pollen to fertilize ovules, researchers conducting hand-pollinations should attempt to control the freshness or viability of pollen used. We surveyed hand-pollination experiments published in seven major journals from 1980 until mid-1994, collecting data on the purpose of the experiment, the degree of care taken to ensure pollen viability, and the degree of care taken to ensure stigmatic receptivity. Fewer than one-third of the papers reported any consideration of pollen freshness or viability, whereas over one-halfmade some mention ofstigmatic receptivity. Pollen freshness or age was mentioned more frequently for some types ofexperiments than for others. Experiments attempting to compare performance of different donors are especially susceptible to error when donor pollen is not treated equally or otherwise controlled for viability. We discuss strengths and weaknesses oftests to measure pollen viability, and experimental protocols to reduce differences in pollen condition across donors.Darwin's concern with the effects of cross-and selffertilization in plants led him to conduct many controlled pollinations in which he collected pollen from particular donors and transferred it to the stigmas ofrecipients (1876, 1877). Controlled pollinations remain a mainstay ofmany investigations today. The questions are diverse, but many still involve comparing the performance ofpollen donors. Classical issues, such as inbreeding effects and the functioning of incompatibility systems, are still of interest, but the recent emphasis on the important role of male function in floral evolution has brought new questions with it: sexual selection and "female choice," resource vs. pollen limitation of seed set, gametophytic selection, etc. We lump all of these issues under the heading of "evolutionary ecology." As documented by Keams and Inouye (1993), publishing activity in pollination biology is soaring, and many of the recent surge of papers use controlled hand-pollination. Although mostly done in the field or in greenhouses with only modest control of the climate, this work is founded on the assumption that differences in the performance of different pollen donors are genetic in origin.There has also been progress in the study of pollen grain physiology. The issue of pollen viability has received attention, and it is now apparent that there is great variability among species in the effective life spans of pollen grains (see, for example, Table 5.2 in Stanley and Linskens [1974] or Tables 4.1 and 4.2 in Shivanna and Johri [1985]). Storage conditions, especially temperature and relative humidity, can have strong effects on the competence of pollen (Johri and Vasil, 196 I; Stanley and Linskens, 1974; I Manuscript Shivanna, Linskens, and Cresti, 199Ia). Workers in this field have devised various tests for pollen viability and vigor, and have used them to d...

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Pollination in an understorey vine, Smilax rotundifolia, a threatened plant of the Carolinian forests in Canada

Cited by 8 publications

References 4 publications

Floral Morphology and Development in Georgia Plume, Elliottia racemosa (Ericaceae), a Rare Coastal Plain Endemic

Floral Morphology and Development in Georgia Plume, Elliottia racemosa (Ericaceae), a Rare Coastal Plain Endemic

Population Matrix Models of Aeschynomene Virginica, a Rare Annual Plant: Implications for Conservation

Assessment of pollen viability in hand‐pollination experiments: a review

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