The influence of petals on reproductive success in the arctic poppy (Papaver radicatum)

Abstract

The flowers of the arctic poppy (Papaver radicatum L.) track the sun, and the petals of the flowers reflect light towards the ovary. This study investigated the importance of petals to reproductive success in this species. We measured light intensity, ovary temperature, seed weight, and number of seeds produced by flowers that had their petals removed versus flowers with their petals intact. Flowers without petals do not track the sun. Irradiance was greater when the photocell was held coincident with the angle of sun-tracking flowers than when facing upward. Flowers with petals had significantly higher overy temperatures both at the ovary surface and in the ovary interior than did flowers lacking petals. In pairs of flowers on the same individual plant, those with their petals removed had significantly fewer and smaller seeds than control flowers with petals intact. There were site differences in the significance of the treatment effect, but not in the magnitude of the differences between flowers with and without petals. Therefore, the presence of petals resulted in increased irradiance and temperature at and in the ovary, which affected reproductive success. Key words: heliotropism, Papaver radicatum, petals, reproductive success, temperature.

The Bracts of Saussurea velutina (Asteraceae) Protect Inflorescences from Fluctuating Weather at High Elevations of the Hengduan Mountains, Southwestern China

“…Kevan, 1975;Morison and Lawlor, 1999) and seed set have been reported in several plant species (e.g. Young, 1984;Corbett et al, 1991;Kudo, 1995). In addition, the growing season at these high elevations in the Eastern Himalayas and Hengduan Mountains is only 10 to 12 weeks (Ohba, 1988;Wang, 2006).…”

Flower heliotropism of Anemone rivularis (Ranunculaceae) in the Himalayas: effects on floral temperature and reproductive fitness

“…Another example is Papaver radicatum Rottb. (Papaveraceae); this Ranunculales member lost sun-tracking behavior when the petals were removed (Corbett et al 1992). Also within the Ranunculaceae, the flower heliotropic movement of R. adoneus was directed by peduncles, as even with the flowers entirely removed its peduncles could still accurately track the sun (Sherry and Galen 1998).…”

“…Also within the Ranunculaceae, the flower heliotropic movement of R. adoneus was directed by peduncles, as even with the flowers entirely removed its peduncles could still accurately track the sun (Sherry and Galen 1998). The function of petals as organs of thermal regulation has also been investigated experimentally in many flower heliotropic species (Kevan 1975;Kjellberg et al 1982;Corbett et al 1992). In these studies, the petals were found to concentrate light upon the gynoecia, suggesting there may be little benefit in solar-tracking in the absence of petals.…”

“…As such, heliotropism in A. rivularis is different than that of R. adoneus in North America (Sherry and Galen 1998). The bowl-shaped tepals drive the flowers of A. rivularis heliotropic movement similarly to the movements of D. octopetala and P. radicatum (Kjellberg et al 1982;Corbett et al 1992).…”

“…In order to compensate for various unfavorable factors, floral traits of some alpine species affect reproductive functions via regulating the microenvironment within flowers. Flower heliotropism, a form of positive phototropism (Kevan 1972;Hart 1990), is considered to be a behavioral adaptation for efficient absorption of solar energy and adjustment of floral temperature (Kjellberg et al 1982;Corbett et al 1992;Kudo 1995;Totland 1996;Luzar and Gottsberger 2001;Galen 2006). Flower heliotropism has been demonstrated in several families, such as Ranunculaceae, Compositae, Rosaceae, Convolvulaceae, and Papaveraceae (Knutson 1981;Stanton and Galen 1989;.…”