Floral biology of North American Oenothera sect. Lavauxia (Onagraceae): Advertisements, rewards, and extreme variation in floral depth
Författare
Summary, in English
We studied the floral biology of five North American members of Oenothera L. sect. Lavauxia (Spach) Endl. (Onagraceae L.) in field and common greenhouse settings. Oenothera sect. Lavauxia floral morphology ranges from small, cleistogamous flowers (O. flava subsp. flava (A. Nels.) Garrett in Garrett) to sonic of the longest-tubed flowers in North America (O. flava subsp. taraxacoides (Wooton & Standl.) W. L. Wagner). Our goal was to compare qualitative and quantitative aspects of floral advertisement and reward among taxa in section Lavauxia. All taxa are night-blooming and self-compatible, have yellow petals with ultraviolet reflectance, and produce floral scents dominated by nitrogenous compounds and monoterpenes. Methyl nicotinate is present in the fragrances of all taxa of section Lavauxia regardless of flower size or putative mating system. Because this floral volatile is largely absent from other Oenothera species, we hypothesize that it is a synapomorphy for section Lavauxia. The rare O. acutissima W. L. Wagner, which is endemic to the Uintah Mountains, is polymorphic for odors dominated by linalool- or ocimene-derived compounds). Field observations in its type locality in northeastern Utah, U.S.A., revealed frequent floral visitation by crepuscular hawkmoths during the first 1.5 hours after anthesis, a pattern common to O. flava subsp. taraxacoides and other large-flowered Oenothera throughout western North America. Quantitative aspects of floral advertisement (flower size, scent emission) and reward (nectar volume) are dramatically reduced in putatively autogamous taxa (O. flava subsp. flava, O. triloba Nutt.). whereas qualitative aspects (flower color, scent, and nectar chemistry) remain comparable. All taxa could be distinguished through ordination of characters related to flower size, herkogamy. and scent chemistry. Extreme nectar tube length variation across the range of O. flava renders this an excellent model system for measuring the costs and mechanisms of shifts between outcrossing and autogamy.
Avdelning/ar
Publiceringsår
2007
Språk
Engelska
Sidor
236-257
Publikation/Tidskrift/Serie
Annals of the Missouri Botanical Garden
Volym
94
Issue
1
Länkar
Dokumenttyp
Artikel i tidskrift
Förlag
Missouri Botanical Garden
Ämne
- Zoology
Nyckelord
- biogeography
- fragrance. nectar
- night-blooming
- Onagraceae
- Oenothera
- floral scent
- pollination
Status
Published
Forskningsgrupp
- Lund Vision Group
ISBN/ISSN/Övrigt
- ISSN: 0026-6493