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POLLEN‐OVULE RATIOS: A CONSERVATIVE INDICATOR OF BREEDING SYSTEMS IN FLOWERING PLANTS
  • R. Cruden
  • Biology, Medicine
  • Evolution; international journal of organic…
  • 1 March 1977
The evolutionary shift from xenogamy (outcrossing) to autogamy (selfing) has been mediated through decreased flower size and alterations in floral morphology (Ornduff, 1969) which reduce theExpand
Pollen grains: Why so many?
  • R. Cruden
  • Biology
  • Plant Systematics and Evolution
  • 1 March 2000
My objective is the examination of selective forces that affect pollen number. Relationships among other floral traits of animalpollinated plants, including pollen size, stigma area and depth, andExpand
Pollinators in High-Elevation Ecosystems: Relative Effectiveness of Birds and Bees
  • R. Cruden
  • Biology, Medicine
  • Science
  • 30 June 1972
During the rainy season bird-flowered plants at high elevations are more effectively pollinated than closely related bee-flowered plants. With good flight conditions the effectiveness of birds andExpand
Correlations Among Stigma Depth, Style Length, and Pollen Grain Size: Do They Reflect Function or Phylogeny?
There is a positive correlation between stigma depth-our approximation of the distance a pollen tube has to grow to reach exogenous resources in the transmission tissue-and pollen grain size, but notExpand
POLLEN‐OVULE RATIO, POLLEN SIZE, AND THE RATIO OF STIGMATIC AREA TO THE POLLEN‐BEARING AREA OF THE POLLINATOR: AN HYPOTHESIS
The initial work on pollen-ovule ratios (P/O's) was predicated on the assumption that P/O's reflected the efficiency of pollination; the more efficient the transfer of pollen, the lower the P/OExpand
REPRODUCTIVE BIOLOGY OF WEEDY AND CULTIVATED MIRABILIS (NYCTAGINACEAE)
The reproductive biology of Mirabilis nyctaginea (Michx.) MacM. contributes to the plant's success as a weed and invader of disturbed habitats whereas that of M. Jalapa L. reflects its success as aExpand
Patterns of biomass allocation to male and female functions in plants with different mating systems
SummaryUsing dry weight biomass we examined the patterns of investment in male and female functions (prezygotic cost) in plants with different mating systems. All the flower parts of both xenogamousExpand
INTRASPECIFIC VARIATION IN POLLEN-OVULE RATIOS AND NECTAR SECRETION-PRELIMINARY EVIDENCE OF ECOTYPIC ADAPTATION'
Because pollen-ovule ratios (P/O's) reflect the predictability of pollinators in a habitat and the efficiency of pollination, large intraspecific differences in P/0's suggest differences inExpand
TEMPORAL DIOECISM: AN ALTERNATIVE TO DIOECISM?
The maintenance of genetic variation in natural populations is usually considered to be important in maintaining ecological plasticity and evolutionary success. In most plants, including autogamousExpand
VISCIN THREADS, POLLINATION EFFICIENCY AND LOW POLLEN‐OVULE RATIOS
Some Onagraceae are characterized by quite low pollen-ovule ratios. We suggest they are an evolutionary response to highly efficient pollination, mediated through viscin threads, which hold largeExpand
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