Rex Begonias: Parenchyma and Propagation

Rex Begonia

Rex begonias – the “king” of the begonias – are plants with their own unique look. These begonias aren’t grown for their blossoms; they’re grown for their foliage which comes in various shapes and colors. Rex begonias are great houseplants and they grow well in outside pots in semi-shaded areas.

What I find interesting about these begonias is the way that you can propagate them. Stem cuttings of these plants root easily but the most common way to multiply rex begonias is by using leaf cuttings.

To do this, you simply take a begonia leaf, turn it over and make a small cut across each of the main leaf veins. Then you place the leaf on potting medium right side up and use pebbles or floral pins to ensure that the back of the leaf is in contact with the medium. Within a month, small plants will begin to grow where the cuts were made on the leaf. These can then be removed and put into separate pots.

I’ve done a lot of propagating over the years but I’ve only recently started using leaf cuttings. I’m amazed how a rex begonia leaf with a few cuts on it can turn into a number of cloned plants.

Adventitious Shoots forming from Parenchyma

What’s even more amazing is how this happens. Within plants there are a number of different kinds of cells and one of them is called parenchyma. This kind of cell is found throughout the plant but is especially present in the leaves. Parenchyma is usually the center part of a leaf, sandwiched between the epidermis cells. In the leaf, parenchyma cells photosynthesize but they also serve for wound healing. In some cases, parenchyma is also the source of adventitious roots and shoots. (Adventitious roots and shoots are simply roots and shoots that grow from an “unexpected” location, like a leaf.)

Adventitious Shoots on a Rex Begonia Leaf

When you take a leaf of a rex begonia and make cuts across the main veins, you expose the parenchyma cells within the leaves and they begin wound healing. But if this leaf is place on a potting medium, the same parenchyma cells will develop adventitious roots and shoots. The roots develop first and then the leaves and shoots will emerge and a new plant will begin to grow.

I find this is fascinating! If we were like a rex begonia, we could cut off our hand, make a cut on each of our fingers, place the hand on a growing medium and clone ourselves. But of course this wouldn’t work – we’re not plants and we don’t have parenchyma! But rex begonias do and it’s amazing to watch a leaf produce a number of small plants, each a clone of the parent plant. All of this is thanks to the parenchyma cells within the begonia leaf.