Streptocarpus candidus abscission lines on the leaves

This is a photo of Streptocarpus candidus from the gesneriphiles list on the Internet. It's a group that chats about all things gesneriad using email. People can ask questions or post photos, answer questions or make comments. If you aren't already signed up for this, you probably should be!

Look here for more info: "gesneriphiles@lists.ibiblio.org" <gesneriphiles@lists.ibiblio.org>

Anyway, I saw this photo posted by Bob Stewart and had to ask permission to put this on our blog because it's so cool. This is Streptocarpus candidus. If you will look carefully at the photo you will see that the leaves are lighter green on the top and there is a defined line and then the regular green on the bottom. These leaves are doing what our trees do in the fall and making an abscission layer and they are planning to shed the upper parts of the leaf to conserve on water.

Bob explained a bit more for me and I'll quote him: "What is happening in the picture is roughly the same thing that happens to an oak tree. In both cases the plant is preparing for winter. In winter, water is in short supply, either because not much
falls or because the water is frozen so the plant cannot get at it.

The plant needs to reduce its water loss, and the way to do this is to
reduce the leaf area. The oak tree forms a layer of waterproof corky
cells at the base of the each leaf petiole, cutting the whole leaf off
from the rest of the tree. The leaf will eventually fall, although in
oaks it may not fall until spring.

The streptocarpus forms a layer of waterproof corky cells part way
down the body of the leaf, cutting the far end of the leaf off from
the rest of the plant. The far end of the leaf will gradually die and
dry or rot away, though in mild situations this may take months.

In spring the oak tree grows whole new leaves from buds along the
stem.

In spring the streptocarpus starts extending the old leaf from a layer
of generative cells near the base. This is the same layer of cells
that produced the leaf in the first place, and the leaf simply gets
longer from the base."

I would very much like to thank Bob for the use and description of the photo and also encourage people to go see about the gesneriphile list. There is a LOT of useful info on it.

Questions??? Comments????