Secondary pollen presentation and the temporal dynamics of stylar hair retraction and style elongation inCampanula trachelium(Campanulaceae)

Plant Biology ◽  
2013 ◽  
Vol 16 (3) ◽  
pp. 669-676 ◽  
Author(s):  
S. Vranken ◽  
R. Brys ◽  
M. Hoffmann ◽  
H. Jacquemyn
2018 ◽  
Vol 24 (4) ◽  
pp. 451-458
Author(s):  
Talita Oliveira Nascimento ◽  
Patricia Campos Silva ◽  
Vivian Loges ◽  
Sandra Mariotto ◽  
Willian Krause ◽  
...  

The secondary presentation of pollen consists of a foral mechanism where the presentation of pollen occurs in other foral structures in addition to the anther, in order to increase the precision of the dispersion of the pollen by the vectors. This study aims to describe the temporal dynamics of secondary pollen presentation, and morphological and morphometric characteristics in stages of pre- anthesis and anthesis in genotypes of fve natural Heliconia psittacorum populations. For the study of foral morphometry traits of length of the fower, stamen, stigma and height of flament insertion in the petal in bud and fower were measured. The foral morphology of pre-anthesis buds and fowers in anthesis, the presence or absence of characteristics such as herkogamy, region of flament insertion in the petal, region of stylar hairs, and of secondary pollen deposition were evaluated. Treatments of controlled pollinations, self-pollination, geitonogamy, cross-pollination, natural pollination and growth to pollen tube were sampled. Floral herkogamy and pollen transfer to the adhered hairs in the stylar region were clearly observed during anthesis, constituting the frst record of occurrence of secondary pollen presentation in Heliconiaceae. Pollen tube growth was inhibited in the stigmatic, style and basal regions of the pistil. Natural fruiting produced little or no fruit. The positioning of the stamens above the stigma, pollen viability and stigma receptivity during anthesis of H. psittacorum fowers may favor self-pollination. The stylar hairs observed in all H. psittacorum populations’ help in the retention of pollen grains. The low fruiting rate in controlled and natural pollinations suggest that the main propagation form of H. psittacorum in the study areas is based on asexual reproduction.


1993 ◽  
Vol 41 (5) ◽  
pp. 417 ◽  
Author(s):  
GJ Howell ◽  
AT Slater ◽  
RB Knox

Secondary pollen presentation is the developmental relocation of pollen from the anthers onto another floral organ which then functions as the pollen presenting organ for pollination. Nine different types have been identified in sixteen angiosperm families according to which organ is used for presentation, whether the pollen is exposed or concealed within a structure and how pollen is loaded onto the presenting surface: (1) Enveloping bloom presenters (Araceae); (2) Perianth presenters with exposed pollen presentation (Epacridaceae); (3) Androecial presenters (Santalaceae); (4) Terminal stylar presenters with passive pollen placement and concealed stigmas (Rubiaceae and Proteaceae); (5) Terminal stylar presenters with passive pollen placement and sub-terminal stigmas (Marantaceae and Polygalaceae); (6) Terminal stylar presenters with active pollen placement (Asteraceae, Calyceraceae and Lobeliaceae); (7) Sub-terminal stylar presenters (Campanulaceae, Cannaceae, Fabaceae and Myrtaceae); (8) Exposed stigmatic presenters (Rubiaceae); (9) Indusial stigmatic presenters (Goodeniaceae and Brunoniaceae). Secondary pollen presentation occurs in three monocotyledon and thirteen dicotyledon families. The presentation types appear to have been independently derived indicating that secondary pollen presentation is a character with a selective advantage. In all but the enveloping bloom type of secondary pollen presentation, developmental relocation of pollen requires simultaneous, introrse anther dehiscence and a close association of the presenting organ to the anthers prior to anthesis. The various secondary pollen presentation systems may be modified to promote xenogamy or autogamy and this can even change during anthesis. Most plants which have secondary pollen presentation, display reduced herkogamy within the flower to facilitate pollination. Increased risk of self-pollination due to this may be overcome through dichogamy, herkogamy within inflorescences, dry stigmas, self-incompatibility systems and passive or active control over pollinator behaviour. Enhanced male function of the flowers of secondary pollen presenting plants is also evident through extension of the male phase by the protection, controlled release and precise placement and receipt of pollen. Plants displaying secondary pollen presentation are almost always protandrous.


Flora ◽  
2012 ◽  
Vol 207 (12) ◽  
pp. 895-902 ◽  
Author(s):  
Hua Lin ◽  
Xuli Fan ◽  
Xiang Zhou ◽  
Jiangyun Gao

1993 ◽  
Vol 41 (5) ◽  
pp. 511 ◽  
Author(s):  
DV Beardsell ◽  
SP Obrien ◽  
EG Williams ◽  
RB Knox ◽  
DM Calder

The diverse floral structures of Australian Myrtaceae are discussed in relation to pollination biology, breeding systems, and ecological and evolutionary relationships. Although the reproductive biology of Eucalyptus has been studied widely, little is known about many of the other genera. The review concludes that additional work is needed on aspects of flower structure, pollination biota, late acting self-incompatibility, secondary pollen presentation and reproductive success.


2016 ◽  
Vol 20 (01) ◽  
pp. 4-15

Oldest Peach Pits Found in China. Big Gene Bank to Anchor Precision Medicine. Koning Receives China Food and Drug Administration Clearance. UC Berkeley, Berkeley Lab Partner with China's Tsinghua on Clean Energy. China's Temperature, Sea Level Rise Faster than Global Average. Pandas prefer choosing their own Sex Partners, Researchers find. How Do Tibetan-Iranian Plateaus Influence the Asian Summer Monsoon? Pollen Chains Associated with Secondary Pollen Presentation in a Wild Ginger Species. Researchers Find Structural Isomerism in Gold Nanoparticles. How Does HCV Escape From Immune Response? Mt. Qomolangma Glaciers Shrink 28 pct in 40 Years: Report. DNA Dates Dog Domestication Back 33,000 Years. Crystal Structures of Human TIM Members: Ebolavirus Entry-enhancing Receptors.


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