Seasonal cleistogamy: a conditional strategy to provide reproductive assurance

Abstract

Three populations of the cleistogamous species Oxalis acetosella and one population of the cleistogamous species Viola hirta (during 2 years), were investigated to determine whether the fertilization success of chasmogamous flowers influences the number of per ramet produced chasmogamous seeds, cleistogamous flowers, cleistogamous seeds and the total number of released seed per ramet. In both species chasmogamous (CH) flowers are produced before the cleistogamous (CL) ones.Fertilization success influenced number of produced CH seeds per ramet. In both species, ramets with one or more unfertilized CH flowers produced significantly fewer CH seeds. The number of produced CL flowers per ramet varied due to site membership (0. acetosella) and ramet size, but also due to the fertilization success of CH flowers. In both species, ramets with some CH flowers left unfertilized, responded with an increased production of CL flowers and seeds. In none of the species did the fertilization success of CH flowers influence the total seed output per ramet. Consequently, the increased production of CL flowers compensatedjor any loss in fruit-and seed-set owing to unsuccessful fertilization of CH flowers.

Biologia reprodutiva e polinização de duas espécies de Polystachya Hook. no Sudeste do Brasil: evidência de pseudocleistogamia em Polystachyeae (Orchidaceae)

“…Além disso, a produção de flores cleistógamas pode assegurar que em condições climáticas adversas, principalmente em regiões que apresentam grande sazonalidade, como a Serra do Japi (Pinto 1992), frutos sejam formados, mesmo na escassez de polinizadores, um processo semelhante ao que tem sido demonstrado para outros grupos de plantas (e.g. Redbo-Torstensson & Berg 1995, Lu 2002). …”

Beyond Simple Reproductive Assurance: Cleistogamy Allows Adaptive Plastic Responses to Pollen Limitation

“…Plastic production of CL flowers in response to CH fruit set is supported by correlative studies (Redbo-Torstensson and Berg 1995;Berg and Redbo-Torstensson 1998) but has not been shown experimentally.…”

Plasticity of Chasmogamous and Cleistogamous Reproductive Allocation in Grasses

“…Theoretical considerations of the evolution of CL have involved comparative cost-benefit analyses of CH vs. CL flower production (Schoen and Lloyd 1984) or variation in the relative fertility of the two floral types (Redbo-Torstensson and Berg 1995;Masuda et al 2001). Because the paternal costs of producing prodigious amounts of pollen in outcrossed spikelets may be high in grasses (e.g., Schoen 1984), maternal reallocation of conserved resources to CL spikelets could enhance plant fitness by increasing the number or size of maturing seeds (Schoen and Lloyd 1984;Lloyd 1987).…”

“…Most species that have CL flowers can and do continue to make open, potentially cross-pollinated chasmogamous (CH) flowers. Because an individual usually can make both floral forms and they may be present at the same time, CL species are often considered to have a mixed breeding system or ''multiple strategy'' (Lloyd 1984;Schoen 1984;Redbo-Torstensson and Berg 1995;Masuda et al 2001). Due to the structural and developmental differences typically found between CH and CL flowers (and sometimes, between the resulting fruits and seeds), CL species are also considered to show reproductive dimorphism (Lord 1981;Clay 1983a;Schoen and Lloyd 1984;Cheplick 1994;Plitmann 1995).…”