''Hibiscus trionum'', commonly called flower-of-an-hour, bladder hibiscus, bladder ketmia, bladder weed, modesty, puarangi, shoofly, and venice mallow, is an

annual plant An annual plant is a plant that completes its life cycle, from germination to the production of seeds, within one growing season, and then dies. The length of growing seasons and period in which they take place vary according to geographical l ...

native to the Old World tropics and subtropics. It has spread throughout southern Europe both as a

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

and cultivated as a

garden plant Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that i ...

. It has been introduced to the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...

as an ornamental where it has become naturalized as a weed of cropland and vacant land, particularly on disturbed ground.

Description

The plant grows to a height of , sometimes exceeding , and has white or yellow flowers with a purple centre. In the deeply pigmented centre of the flower, the surface features striations, which have been the subject of controversy about whether they act as a

diffraction grating In optics, a diffraction grating is an optical component with a periodic structure that diffraction, diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form ...

, creating

iridescence Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butter ...

. The pollinated but unripe seedpods look like oriental paper lanterns, less than across, pale green with purple highlights. The flowers of ''Hibiscus trionum'' can set seed via both

outcrossing Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity. Outcrossing can be a useful ...

and

self-pollination Self-pollination is a form of pollination in which pollen from the same plant arrives at the stigma of a flower (in flowering plants) or at the ovule (in gymnosperms). There are two types of self-pollination: in autogamy, pollen is transferred to ...

. During the first few hours after

anthesis Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period. The onset of anthesis is spectacular in some species. In ''Banksia'' species, for example, anthesis involves the extension ...

, the style and stigma are erect and receptive to receive pollen from other plants. In the absence of pollen donation, the style bends and makes contact with the

anthers The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

of the same flower, inducing self-pollination. Although outcrossing plants seem to perform better than self-pollinating plants, this form of reproductive assurance might have contributed to the success of ''H. trionum'' plants in several environments.

Photonic properties

Initial studies showed that artificial replicas of the flower surface produced iridescence that bees could recognise. Later work suggested that the irregularities of the plant cells and surface resulted in the periodicity of the striations being too irregular to create clear iridescence and thus suggested that the iridescence is not visible to man and flower visiting insects. More recent papers have presented evidence that the flower is both visibly and measurably iridescent, and the striations have been shown to be sufficiently irregular to generate particularly strong scattering of light at short wavelengths, producing weak iridescence and a 'blue halo' (of which the halo is the dominant visible effect). It has also been demonstrated that the blue scattering increases the foraging efficiency of bumblebees in laboratory environments, although it remains unknown whether this effect translates to a meaningful advantage in the field.

References

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External links

* {{Taxonbar, from=Q157854 trionum Flora of Western Asia Flora of Palestine (region) Flora of Israel Flora of Lebanon Garden plants of Asia Plants described in 1753 Taxa named by Carl Linnaeus