Farm Focus: The Birds & The Bees of Blossom Pollination
This time of year the name of the game is pollination. Our entire harvest is dictated by this process’ success so we thought it would be a good opportunity to dive into this ever important subject!
Just like other sexual organisms flowering plants reproduce by combining genetic material (pollen and ovule) to form a zygote. That zygote will mature into a seed (surrounded by fruit) that will, under the right circumstances, grow into a seedling and go on to complete this same process. Fruit, whether a cherry, olive or pomegranate, is basically fertilized eggs covered in a protective husk (seed) and stored energy (fruit flesh). The fruit’s flesh provides stored energy for the growing seedling but can also attract animals who help disperse the mature seeds. As humans have evolved to become better and better farmers we have learned to control this process to make plants that produce fruit to meet our needs.
Although most folks identify flowers by their showy petals, the real action is happening in the middle of the flower where pollination occurs. Some might remember the reproductive parts of a flower from Biology 101 but let’s review for those of us who have forgotten!
There are two main reproductive parts to flowers: Stamen and Pistil. The stamen is made up of the anther, which produces pollen (male sperm cells) and the filament which acts as a stem. The Pistil is the part of the flower that produces the ovule which is made up of the stigma on the tip, supported by the stem-like style and the ovary at the base which contains the ovule (female egg cells).
So how does the pollen travel from the anther to the ovary? That’s where wind, animals, insects and farmers like us come in. Some fruit, like olives, are wind pollinated so they don’t have petals to block pollen from blowing in the air on to the stigma. Fruit in the prunus family, like our beloved stone fruit, have flowers that reward insects for helping pollination occur with food. Insects like bees are attracted to the bright flowers that are easy to see and small so they can access sweet nectar and protein rich pollen. The anther sticks out on the filament so that bees can easily collect this pollen on their legs to take back to the hive.
Hopefully, as pollinators fly around to other flowers, some pollen falls off and lands on a mature stigma. This pollen is then transported down the inside tube of the style and into the ovary where it will hopefully fertilize the awaiting ovules.
Now, it can get a lot more complicated than that. Some species have separate male and female trees that have to be in close proximity to share pollen. Other trees require pollen from a different variety in order to fertilize. No matter, once fertilization occurs the tree has to have the right conditions, resources and time to mature a delicious ripe fruit.
We can actually tell when a flower has been pollinated by gently pinching the base of the flower. When the ovary begins to swell, like the one in this picture, that means pollination has occurred and a fruit is on its way. Some fruit, like certain varieties of grapefruit can take up to 18 months but luckily most or our stone fruit only takes 3-6 months to ripen so the wait will be over soon!