The reproductive isolation among sympatric Pedicularis species is influenced by the differences of pollinator behavior and floral form via ethological isolation and mechanical isolation.
The flowers were pretreated by (A) emasculating then bagging, (B) removal of stigma and (C) crosspollination, respectively as compared with control: open-pollination after emasculation.
Diocletian's mausoleum dominated the center of the palace complex. Much of the original Roman building survives - the impressive dome, columns and capitals, and fine carved reliefs.
With plants having separated sexes, and with those in which, though hermaphrodites, the pollen does not spontaneously fall on the stigma, some aid is necessary for their fertilisation.
Among the truncated leaves the passion flower opens pale lavender rosettes, fringed and marked at the center with the stigmata, and with stamens indicating the number of the apostles.
When pollen from a plant of one family is placed on the stigma of a plant of a distinct family, it exerts no more influence than so much inorganic dust.
The idea in pollination is if an animal or the wind or whatever takes pollen from a stamen and deposits it on these stigmas, you can see some pollen grains dropped off here.
Every hybridizer knows how unfavourable exposure to wet is to the fertilisation of a flower, yet what a multitude of flowers have their anthers and stigmas fully exposed to the weather!
It has also been observed that when the pollen of one species is placed on the stigma of a distantly allied species, though the pollen-tubes protrude, they do not penetrate the stigmatic surface.
Now, in certain orchids similar viscid matter is secreted, but in much larger quantities by one alone of the three stigmas; and this stigma, perhaps in consequence of the copious secretion, is rendered sterile.