Floral scent plays important roles in basal angiosperms such as the pantropical woody family Annonaceae. The North American genus Asimina (Adans.) (Annonaceae) includes eight species of shrubs and small trees, of which Asimina triloba has the broadest and northernmost distribution. We characterized the yeastlike fragrance of these flowers using gas chromatography-mass spectrometry in natural populations in South Carolina. The odors of A. triloba and baker's yeast Saccharomyces cerevisiae shared ethanol, ethyl acetate, acetic acid, and other compounds but differed in relative amounts of 3-methyl-1-butanol, 3-OH-2-butanone, and butane-2,3-diol. Immature green flowers of A. triloba produced sesquiterpenes common to the foliage of many plants. In contrast, sexually mature flowers emitted fermentation volatiles, with additional nitrogenous compounds (androgynoecium) and butanediols (outer corolla) emitted by male flowers. Some compounds were detected only when scent was sampled from at least 10 flowers. Chemical composition was more complex during day than night for immature and female flowers but not for males. Emission rates were fourfold greater in male than female flowers during the day but were comparable at night, perhaps because of overlapping gender expression. The yeasty odor of A. triloba is unusual in angiosperms and may serve to attract novel fly and beetle pollinators.

Summary• Floral scent is a key component of floral display, and probably one of the first floral attractants linking insect pollinators to the radiation of Angiosperms. In this article, we investigate floral scent in two extra-tropical genera of Annonaceae. We discuss floral scent in the context of differing pollination strategies in these genera, and compare their scent to that of a close tropical relative.• Floral volatiles were collected for Annona glabra, Asimina and Deeringothamnus whole flowers and dissected floral organs, using a standardized static-headspace solid phase microextraction method. Scents were analyzed using gas chromatographymass spectrometry, and identified using known standards.• The floral scents of these species are highly dynamic, varying between floral organs, sexual stages and species. Maroon-flowered species of Asimina produce 'yeasty' odors, dominated by fermentation volatiles and occasionally containing sulfurous or nitrogenous compounds. White-flowered species of Asimina and Deeringothamnus produce pleasant odors characterized by lilac compounds, benzenoids and hydrocarbons. Annona glabra produces a strong, fruity-acetonic scent dominated by 3-pentanyl acetate and 1,8-cineole.• The fermented/decaying scents of maroon-flowered species of Asimina suggest mimicry-based pollination strategies similar to aroids and stapeliads, whereas the pleasant scents of white-flowered species of Asimina suggest honest, reward-based pollination strategies. The scent of Annona glabra is typical of specialized beetle pollination systems common to tropical Annonaceae.

Many species of Annonaceae are known for their distinctive, penetrating floral aromas. Numerous pollination studies have documented floral scents which probably play a key role in specialized pollination strategies. In particular, floral scents appear to play crucial roles in deceptive pollination strategies, contributing to floral mimicry of ripe or decaying fruits, fungi and, potentially, carrion or faeces. Occasionally, floral scent may advertise genuine floral rewards, as is the case for two species of Unonopsis pollinated by male euglossine bees. To date, ten studies have chemically characterized floral scent for 24 species representing 11 genera of Annonaceae. In this review, I discuss the chemical composition and diversity of the analysed floral scents in Annonaceae. I also summarize and discuss a wide range of (human) perceptual descriptions of floral scent found throughout the literature on Annonaceae. I have framed discussions of floral scent in Annonaceae in ecological and evolutionary contexts whenever possible. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169, 262–279.

This experiment combines analytical techniques of solid phase microextraction and gas chromatography−mass spectrometry with easily relatable and accessible plant volatile chemistry (floral and vegetative scents of local/available plants). The biosynthesis and structure of these chemicals are of interest in the areas of organic chemistry, biochemistry, and molecular biology. This laboratory exercise is well-suited for a broad range of cross-disciplinary topics in chemistry and biology courses. The methods described here could be used to expose undergraduate chemistry students to broad aspects of biological volatile chemistry in plants, and alternatively, to expose undergraduate biology students to analytical chemistry techniques useful in the study of plant biology and plant−insect interactions.

Floral mimicry of nonfloral resources is found across many angiosperm families, with mimicry of varied models including carrion, dung, fungi, insects and fruit. These systems provide excellent models to investigate the role of visual and olfactory cues for the ecology and evolution of plant-animal interactions. Interestingly, floral mimicry of fruit is least documented in the literature, although ripe or rotting fruits play an important role as a food or brood site in many insect groups such as Diptera, Hymenoptera and Coleoptera, and frugivorous vertebrates such as bats and birds. In ecosystems where fruit represents a frequent, reliable resource (e.g. tropical forests), this form of floral mimicry could represent a common mimicry class with specialization possible along multiple axes such as fruit of different species, stages of ripeness and microbial colonization. In this review, we summarize current research on floral mimicry of fruit. We place this review in the context of floral mimicry of a broader spectrum of nonfloral resources, and we discuss conceptual frameworks of mimicry vs generalized food deception or pre-existing sensory bias. Finally, we briefly review the specificity and complexity of fruit-insect ecological interactions, and we summarize important considerations and questions for moving forward in this field.

Biomechanical data showed that pawpaw twigs were "twistier" than the comparison species, which were shown previously to alleviate drag-induced damage by reorienting petioles and leaves. Pawpaw has an unusual strategy of low torsional stiffness in twigs, allowing for reorientation of the entire distal appendage, likely minimizing drag-induced damage in storms.

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