Thursday, December 21, 2006

Pretty patterns

Here's a shot of some very handsome leaves! This photo, shared by S. J., comes from the national show in Tucson in 2004.

Variegation in African Violet plants comes from some interesting sources. Traditional breeding using the natural variation that exists among members of a wild population will produce offspring that show differences. Depending on the type of organism involved, these "differences" can be very slight or quite noticeable. All natural populations that use cell division to reproduce will occasionally have mutations occur.

According to Gerald Klingaman, it is estimated that one in approximately a million cell divisions will produce a mutation. This means that something has gone wrong with the division process and an identical copy of the parent 's genes has not been produced. Most of these mutations have no effect, some are detrimental, but once in a great while you'll get one that's beneficial. One person's beneficial might not be another person's idea of a good mutation but in the case of the African Violet these mutations will be valued if they produce changes in patterns and colors.

Besides traditional breeding, violets can be induced to "change" when their genetic numbers are doubled, tripled or quadrupled. This condition is called polyploidy. Variations can also be produced with interspecific breeding, or crossing species that are within the same genus. And, you can get a whole exciting range of possibilities with "mutation breeding".

Mutation breeding involves deliberately trying to change the genetic structure of an organism by exposing it to things like chemicals or radiation. In the 1920's x-rays were used to change plant material and people liked the interesting effects that were turning up. Then chemicals were shown to cause genetic changes and even today people are very cautious about what they're exposed to because chemicals can indeed cause genetic changes like cancer or birth defects. Then in 1945 nuclear radiation was found to make all sorts of genetic changes! Gamma rays were used - people could even send in their seedlings or seeds to the Oak Ridge Nuclear Reactor in Tennessee to have their plant material zapped. The changes that were produced were interesting but tended to be unstable.

All of these methods of changing the look of a plant have given the African Violet we see today tremendous possibilities for interesting flowers and foliage. What sorts of violets are you most fond of? Variegates, doubles, crinkled leaves? Let us know what you think would make a good looking plant if you could pick all the traits!

Tuesday, December 19, 2006

Pretty colors

Here's a shot of a handsome 'Party Boy'! Did you know that streps are primarily found in Africa and Madagascar? It will be interesting to see where hybridizing takes the Streptocarpus in the near future because of all the variation in the species plants.

Some of the species streps are unifoliate, or have only one leaf. Some are very similar and tend to grow one to three leaves, but unlike the former, these will be perennials and continue to grow even after flowering and fruiting.

A third form of Streptocarpus is called rosulate. This is the one we might be most fimiliar with because many of the modern hybrids come from stock that includes S. rexii.

Although Streptocarpus don't "branch" as we tend to think of it, there is a fourth sort of strep that produces multiple leaves from a lengthened central base that is capable of producing "secondary" leaves that also are able to bloom. It's sort of intermediate between what we think of as a strep with no "stems" and a regular vegetative plant that develops a branching habit.

The subgenus of Streptocarpus, called Streptocarpella, display yet another form of growth from the one cotyledon which continues to grow, a characteristic feature of the entire genus. (One cotyledon grows while the other withers and dies shortly after germination although it is a fully dicotyledenous plant.) Streptocarpella leaves start as a vegetative bud on the root system and branches in the normal way. In other words, we have everything from rosette plants with no obvious stems to regular branching herb-type plants with more normal leaves. This leaves a great deal of interesting possibilities for hybridization.

Does anyone want to try some strep hybridizing? What would you use for parent plants? What traits would you like to see expressed in future flowers??? Let us know.