Jennifer Schultz Nelson
Extension Educator, Horticulture
When I brought my latest horticultural curiosity into my new office, I got some interesting reactions. One person asked why I had a meatloaf with plastic ferns stuck into it on my desk. Another asked why I chose to put a cow pie on my desk. Of course the answer was neither. In fact the object on my desk is a redwood burl, and it is busy growing my very own redwood forest, though on a smaller scale.
Burl tissue commonly forms in redwood species, as well as other woody plants. Typically on redwood, burls develop from axillary buds at the base of a young seedling. They are composed of stem tissue that multiplies, but never elongates and develops as a shoot. The burl grows as the tree develops, forming a knotted, woody, enlarged mass that may be above the soil level, but grows downward as time goes on.
In the forest, the burl can be considered a survival mechanism. In a healthy tree, the tree produces chemical signals that keep the stem tissue in the burls from developing into shoots. If the main tree dies, the chemical signal is gone, and the stem tissue in the burls will come to life and shoots will form. In the right environment, the shoots may develop into full grown trees.
The burl can also be a unique houseplant. Redwood burls will come to life if separated from the parent tree and kept in a shallow saucer of water, like the one on my desk. Interestingly, redwood is extremely resistant to rot, even when kept constantly wet. The nursery owner I bought mine from in California said it will easily grow and be happy for years to come. It's unlikely that my desk is the ideal environment for a full grown redwood forest, but I do have a nice crop of delicate green branches that provide an interesting sight for my co-workers.