Pollen loads of honeybees, bumblebees and hoverflies were analysed and pollination efficiency estimated, while they were visiting the flowers of Prunus spinosa L. (Blackthorn); Crataegus monogyna Jacq. (Hawthorn); Rosa canina L. (Dog Rose) and Rubus fruticosus L. (Bramble). The relative efficiency of the different insect groups varied, depending on the plant species being visited. In every instance the high constancy of the visitors, their rapid foraging rates and the amounts of pollen they carr
y, would ensure that they are adequate pollen-transfer agents.
Flowering pattern, mating system, and seed set were investigated for four species of Pedicularis: P. lanata (syn. P. kanei), P. hirsuta, P. flammea, and P. lapponica in West Greenland. Pedicularis lanata depends on insects for seed set. P. hirsuta and P. flammea are able to set seed by autodeposition, but P. flammea less successfully than P. hirsuta. Pedicularis lapponica mainly propagates vegetatively. Insects are rarely seen visiting the four species in the investigated area. In P. lanata the
number of germinated pollen grains per stigma is much lower on average than the number of ovules per ovary, and the seed set is consequently well below its potential. Accordingly, we believe that pollen availability limits seed. Multispiked individuals of P. lanata have a lower seed set and a higher mortality rate than single-spiked plants. Pedicularis hirsuta allocates most resources to reproduction and has the highest P/O-ratio and relative reproductive success (RRS) in the area, thus being the most successful species of the four regarding seed production. Pedicularis lanata has the lowest relative reproductive success of the three sexually reproducing species due to low seed set. The four species possess flowers adapted for insect pollination, but are using different and alternative means to maintain populations: vegetative propagation, autogamy, visits by unspecialized insects, and by being perennial.