• Publications
  • Influence
POLLINATION SUCCESS IN A DECEPTIVE ORCHID IS ENHANCED BY CO-OCCURRING REWARDING MAGNET PLANTS
TLDR
Results provide support for the existence of a facilitative magnet species effect in the interaction between certain nectar plants and A. morio at a site in Sweden.
The pollination niche and its role in the diversification and maintenance of the southern African flora
  • S. Johnson
  • Environmental Science
    Philosophical Transactions of the Royal Society B…
  • 12 February 2010
TLDR
The evidence that disturbance provokes pollination failure in some southern African plants with specialized pollination systems is considered, to consider the risk of plant extinction.
Evolutionary associations between nectar properties and specificity in bird pollination systems
TLDR
It is shown that the dichotomy between hummingbirds and passerine birds select for different nectar properties in the plants they pollinate is false and a more useful distinction is that between specialized and generalized bird pollination systems.
Dark, bitter-tasting nectar functions as a filter of flower visitors in a bird-pollinated plant.
TLDR
The main effect of the phenolic compounds that impart a dark brown color to the nectar of the South African succulent shrub Aloe vryheidensis appears to be to repel "unwanted" nectarivores that find their bitter taste unpalatable.
Darwin's beautiful contrivances: evolutionary and functional evidence for floral adaptation.
TLDR
A contrast between the inconsistent occurrence of phenotypic selection and convincing experimental and comparative evidence that floral traits are adaptations is revealed and suggests that the tempo of creative selection varies.
POLLEN CARRYOVER, GEITONOGAMY, AND THE EVOLUTION OF DECEPTIVE POLLINATION SYSTEMS IN ORCHIDS
TLDR
The data indicated that the evolution of nectar production in deceptive Orchis species would result in moderate to high levels of geitonogamy, as a consequence of the greater number of flowers probed and longer visit duration by pollinators, however, the estimated levels were less than expected.
Function and Evolution of Aggregated Pollen in Angiosperms
  • L. Harder, S. Johnson
  • Environmental Science
    International Journal of Plant Sciences
  • 1 January 2008
TLDR
The ability of orchid pollinia to reduce diminishing returns during pollination may explain both the floral diversity and the widespread occurrence of deceit pollination in this clade.
The pollination ecology of an assemblage of grassland asclepiads in South Africa.
TLDR
Nestedness analysis of the data set showed that there was predictability and structure to the pattern of plant-pollinator interactions, with generalist insects visiting specialized plants and vice versa, and the research has shown that there is still much to be learned about plant- pollinator interactions in areas of high plant diversity such as South Africa.
Reproductive biology of Australian acacias: important mediator of invasiveness?
TLDR
Invasive species respond quicker to disturbance than non-invasive taxa and are more commonly able to resprout, although only time to reproductive maturity was significant when phylogenetic relationships were controlled for.
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