Sunday, February 22, 2009

Streptocarpus: Sex

This is a pictorial commentary on how to pollinate a Streptocarpus flower. I purposely took most of the color out of the photos to highlight some of the specific details of the photo. Please CLICK ON THE PHOTO to enlarge it and get a better look at what we're talking about.

The first photo shows a strep flower cut open. The male parts of the flower, the anthers (or pollen sacs) and the filaments are shown. They are attached directly to the lower lobes of the strep flower petals or corolla. They grow right out of the pretty colored petals.

The second photo shows a tweezers holding the joined pollen sacs of the same strep flower. The pollen sacs are whole and unbroken in the photo. The pollen is inside and it would look like dust to the person looking at it if they weren't using a magnifier or microscope.

The third photo is of the female parts of the strep flower. The roundish end part is the stigma which the pollen sticks to and where the process of fertilization begins. The stigma is part of the female portion of the flower called the pistil. The stigma is sort of fuzzy and sticky and that helps keep the pollen in contact with it.

The fourth photo shows the tweezers that are holding the pollen sacs coming into contact with the stigma. The pollen sacs need to be "ripe" or mature and broken open so the dusty pollen grains inside can come into direct contact with the female parts. When the pollen grain comes into contact, a whole process of chemical changes take place. A small tube (a pollen tube) is grown down the length of the pistil all the way to the ovary (at the base of the flower where the flower petals join the green calyx and the pedicil or stem of the blossom). The male genetic material then joins the female genetic material in the flower and the flower is "fertilized". Seeds can now form. If the male DNA isn't allowed to contact the female flower in a reasonable amount of time the flower fades and dies and no seeds or fruits are formed.

As an example of this, you will probably recall that some years there is an abundant crop of apples and some years the crop is very sparse. One of the possible reasons for this happening is that the weather is so cold some springs that the insects that normally pollinate the apple tree are not flying about because of the cold temperature. The apple trees bloom because they are genetically programed to do so, but there are very few pollinators to carry the pollen to the stigmas of waiting flowers.... the flowers fade and drop off and only a tiny fraction of the possible flowers have been pollinated. There will be very few apples forming on the tree that season.

The last photo is is of a newly forming seed pod (or developing ovary). You will notice the twisting nature of the pod (that's the reason why they are called streptocarpus - strep meaning twisted). The flower right next to it has had the petals removed to show the contrast between a non fertilized flower and the newly maturing fertilized one.

Like the apple example discussed above, the strep seed pod is comparable to the apple forming on the tree with the seeds inside it. When it's ripe, the apple seeds will be ready to come out of the apple and grow new apple trees and when the strep seed pod is ripe, the seeds in the cutely twisted pod will be ready to come out and form new streptocarpus plants.

All of the seeds will have unique genetics, just like each child born is unique (unless you consider identical twins which came from one egg that doubled itself). So, all the strep babies that you grow out have the potential to be interesting and unique. Many will look like the parents, but some will not.