With the bees pollinating them less effectively, the plants increasingly self-pollinate
. In a greenhouse evolution experiment, scientists have shown just how much the effects of pollinators and pests influence each other.
Another project is seeking to identify potential lucerne genotypes that have the ability to self-pollinate
in the absence of bees.
The degree to which a plant is able to self-pollinate
, depends on the position and the time of release of anthers in relation to the stigma (Free, 1993).
Alternatively, the ability to self-pollinate
might also serve to counteract pollinator unpredictability and facilitate reproductive assurance when pollinator visits are limited (Levin, 1972).
affinis are especially good pollinators, since even plants that can self-pollinate
produce more and bigger fruit when pollinated by the rusty patched bumblebee.
Most tomatoes will self-pollinate
, but sometimes insects carry pollen from one variety to another.
Heirloom seeds are from plants whose flowers self-pollinate
. Some varieties of vegetables and flowers may not have been around long enough to be called ''heirlooms,'' but still might be from self-pollinating plants.
This ability to self-pollinate
and remain relatively stable is perhaps part of the reason many heirloom varieties have survived.
First, there is an impressive body of literature that shows that many orchid species self-pollinate
when pollinators are rare or absent (Burns-Balogh & Bernhardt, 1988; Catling, 1990; Neiland & Wilcock, 1998).