Nectar Production and Pollination of Asclepias exaltata

Wyatt, Robert; Shannon, T. Randolph

doi:10.2307/2419123

Cited by 27 publications

(13 citation statements)

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“…Pollen germination does not occur in dry chambers, and the stimulus is related to nectar concentration (Jaeger 1971;Pant et al 1982;Eisikowitch 1986;Kevan et al 1989;Wyatt & Broyles 1994). This concentration may vary during the day (Wyatt & Shannon 1986). If the pollinium is inserted when the nectar concentration is not suitable, germination will only take place when it is appropriate (Eisikowitch 1986).…”

Section: Functionmentioning

confidence: 99%

Corona development and floral nectaries of Asclepiadeae (Asclepiadoideae, Apocynaceae)

Monteiro

Demarco

2017

Acta Bot. Bras.

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Flowers of Asclepiadoideae are notable for possessing numerous nectaries and elaborate coronas, where nectar can accumulate but is not necessarily produced. Given the complexity and importance of these structures for reproduction, this study aimed to analyze the ontogeny of the corona, the structure and position of nectaries and the histochemistry of the nectar of species of Asclepiadeae. Two types of coronas were observed: androecial [C(is)] and corolline (Ca). Th e development of the C(is)-type of corona initiates opposite the stamens in all species examined with the exception of Matelea in which it begins to develop as a ring around the fi lament tube. Despite their morphological variation, coronas typically originate from the androecium. A notable diff erence among the studied species was the location of the nectaries. Primarily, they are located in the stigmatic chamber, where nectar composed of carbohydrates and lipids is produced. A secondary location of nectaries found in species of Peplonia and Matelea is within the corona, where nectar is produced and stored, composed of carbohydrates and lipids in Peplonia and only carbohydrates in Matelea. Th e functional role of nectar is related to the location of its production since it is a resource for pollinators and inducers of pollen germination.

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Section: Functionmentioning

confidence: 99%

Corona development and floral nectaries of Asclepiadeae (Asclepiadoideae, Apocynaceae)

Monteiro

Demarco

2017

Acta Bot. Bras.

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“…We acknowledge that through bagging we may have created increased nectar volumes compared with unbagged umbels and that this may have biased visit duration. However, bagging mimics the natural situation when fl owers fi rst open or when their nectar has been " recharged " ( Wyatt and Shannon, 1986 ).…”

Section: Study Site and Species -mentioning

confidence: 99%

Differential pollinator effectiveness and importance in a milkweed (Asclepias, Apocynaceae) hybrid zone

Stoepler

Edge

Steel

et al. 2012

American J of Botany

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We conclude that Bombus may be a key agent of hybridization and introgression in these sympatric milkweed populations, and hybrids are neither preferred nor selected against by pollinators. Thus, we have identified a potential mechanism for how hybrids act as bridges to gene flow between A. exaltata and A. syriaca. These results provide insights into the breakdown of prezygotic isolating mechanisms.

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“…These differences are documented in several species and it is common for older flowers to have a lower volume of nectar. They may have higher or lower solute concentrations than younger flowers (Wyatt & Shannon, 1986;Navarro, 2001;Nicolson & Nepi, 2005).…”

Section: Intraspecies Variabilitymentioning

confidence: 99%