When we think of senescence we usually think of deciduous trees. Not huge, tropical canopied, thorny and dangerous Brazilian raintrees. Senescence happens to all trees. Even junipers and pines. Those third year needles that you clean off a pine? If you left them they’d turn brown and fall off. That old browning scale foliage on a juniper? Same thing.
Oh, wait?! Did I mention that it’s December? But….aren’t we NOT supposed to be working on tropicals at this time? Sorry, you’ve never heard that from me, my friends. Especially on BRT’s.
Let’s discuss the tropical legume we call the Brazilian Raintree (chloroluceun tortum). In Brazil it’s called tataré, and it’s native to the coast of Rio de Janero, in an area called restinga, a wet coastal stretch that goes from tropical to subtropical areas on the eastern shore of Brazil. It’s home to a broadleaf forest that has sandy soil that is both acidic and nutrient poor. A good place for a legume, which has the ability, working in symbiosis with a nitrogen fixing bacteria to, amazingly, pull nitrogen out of thin air and fertilize itself. The BRT is also a type of tree called a monsoon or drought deciduous tree. The restinga is a biome (an environmental designation) called a tropical/subtropical dry forest, bane forest or just monsoon forest. It is a place that gets a lot of water but also has a dry season, where the trees have adapted by dropping their leaves, just like deciduous trees in the northern climes do in the winter.
This is senescence in BRT’s. Droopy, off color, wimpy looking. Like some bonsai artists I know. Senescence is an adaptation by plants, in response to drought or low light levels, that, using the hormone abscisic acid, puts a tree into dormancy. It is the act of abscission, dropping leaves, that gave the name to abscisic acid.
But enough of that, how does all this relate to doing bonsai on a BRT? It means that we must be the stewards, the midwives, the facilitators, of the tree. Time to defoliate again. Before. Like they say, you can prick your finger but you can’t finger your pri…..Ouch, right in the cuticle.
Here’s a quick pruning lesson. The red and blue arrows are pointing to nodes. The node is from whence the new leave or branch emerges. The space between the nodes is called an internode. This is true of all trees. Learn the words and you’ll be thought smart, like me. Or just be called a smart-ass.
On the BRT this is important because of a process called dieback.
Again, the circle is encompassing the node and the internode. Dieback can be significant on a BRT, it’s the process during which the tree compartmentalizes a wound so that it can heal. To be precise, if I cut here at the red line…..the branch will die back to that main branch. Which is fine because I would want to remove the branch to there anyway. The problem is that it is taught to prune flush with the branch on most trees. If you do that on a BRT, the dieback will go like so:and you’ll lose that whole branch to the next node. Therefore, you will see that I leave nubs on all my pruning points; it’s not lax scissor discipline but an understanding of the horticulture of the BRT. Does this mean that we can’t prune flush? No. Once the branch dies back, you can then do a flush cut.
I’ve broken a few rules I usually insist upon but I will always listen to what the tree is telling me.
You’re wondering about the very first tree, aren’t you? We haven’t seen it for a while have we? Don’t worry, there will be a YouTube video on it but, to hold you over, here’s the after pic. Lots of work.
Stay tuned for the video, I think it’s gonna be a cool one.
So, what did we learn today? We learned about senescence, about nodes and internodes and dieback. We learned about fingers and pricks. And that’s all I have to say about that.