Sunday, January 21, 2007

The Usambaras Mountains

Our elephant friend is thinking fondly of something that reminds him of his original home. Many of the "species violets" are currently found growing in the east part of Africa in the Usambaras Mountains of Tanzania. Is this their original, ancestral home?

Because so many of the species violets are found and collected in the Usambaras' this led many to conclude that this must be where violets originated.

A majority of the current hybrid violets that we grow get their genetics from one of these species called Saintpaulia ionantha. It has long been thought that ionantha was the "ancestral" violet that the rest of the species have evolved from. Ionantha is found primarily in the Usambaras Mountains too. But, recent studies using ribosomal DNA evidence have come up with some surprising results.

It's likely that Saintpaulia goetzeana is the plant that is the true ancestor of the African violet. Its genetics are the most closely related to the subgenus Streptocarpella, and many of it's morphological characteristics, including the elongated internodes between small opposite leaves and the blue or blue/white flowers lead to that conclusion.

The S. goetzeana is found in the Uluguru Mountains which are further south in Africa. This is likely where violets actually originated, moving north into new niches where we find many of the species today. Eleven of the species that are found in the Usambaras', including ionantha, velutina, difficilis and grandifolia are exactly the same in ribosomal DNA according to a study by Moller and Cronk. Because the genetics are so similar it can be concluded that they are more "recent" species that are still in the process of differentiating themselves. They are perhaps only 10,000 years old.

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