HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

What's this?

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Pauw, A. Search for Related Content PubMed Articles by Pauw, A. Agricola Articles by Pauw, A. Social Bookmarking                            What's this?

Inversostyly: a new stylar polymorphism in an oil-secreting plant, Hemimeris racemosa (Scrophulariaceae)¹

Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602 South Africa

A new kind of stylar polymorphism, provisionally called inversostyly, is described. The polymorphism occurs in Hemimeris racemosa (Scrophulariaceae), a common annual herb of the Cape region of South Africa. Most populations are dimorphic for style orientation: the style alternates with the two stamens and is deflected either upwards or downwards. Thus, there is reciprocal placement of the style and stamens in a vertical plane in zygomorphic flowers. The flowers are symmetrical, and the floral parts do not vary in length. All flowers on a given plant are of the same stylar orientation. Pollination is by specialized oil-collecting bees (Rediviva spp.), which carry the pollen of the two morphs separately in discrete anterior or posterior locations on the underside of the body. Most inversostylous populations have a slightly higher proportion of the style-down morph, and this bias increases with decreasing pollinator abundance. In contrast with inversostylous populations, all individuals in homostylous populations of H. racemosa have the style and the stamens clustered together in the down position and high levels of autogamous seed set. Homostylous populations of H. racemosa, as well as the homostylous species Hemimeris sabulosa, occur where oil-collecting bees are less abundant.

Key Words: distyly • enantiostyly • evolution of selfing • Hemimeris sabulosa • heterostyly • mating system • morph ratio • reproductive biology

CiteULike    Complore    Connotea    Del.icio.us    Digg    Facebook    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				S. C. H. Barrett Darwin's legacy: the forms, function and sexual diversity of flowers Phil Trans R Soc B, February 12, 2010; 365(1539): 351 - 368. [Abstract] [Full Text] [PDF]

				S. S. Renner and H. Schaefer The evolution and loss of oil-offering flowers: new insights from dated phylogenies for angiosperms and bees Phil Trans R Soc B, February 12, 2010; 365(1539): 423 - 435. [Abstract] [Full Text] [PDF]

				S. D. Johnson The pollination niche and its role in the diversification and maintenance of the southern African flora Phil Trans R Soc B, February 12, 2010; 365(1539): 499 - 516. [Abstract] [Full Text] [PDF]

				A. Cosacov, J. Nattero, and A. A. Cocucci Variation of Pollinator Assemblages and Pollen Limitation in a Locally Specialized System: The Oil-producing Nierembergia linariifolia (Solanaceae) Ann. Bot., November 1, 2008; 102(5): 723 - 734. [Abstract] [Full Text] [PDF]

				A. Pauw Floral syndromes accurately predict pollination by a specialized oil-collecting bee (Rediviva peringueyi, Melittidae) in a guild of South African orchids (Coryciinae) Am. J. Botany, June 1, 2006; 93(6): 917 - 926. [Abstract] [Full Text] [PDF]