Many of you read my post from a few weeks back, “The Humble Bud – Sign of Things To Come.” The bud is the means by which any plant grows to its genetic limit and is able to remain alive for the duration of its lifespan. Most of them begin as a very small thing – some invisible to the naked eye. Yet within such a small package lies the entire means by which a bonsai artist can create a miniature representation of nature.
The humble bud turns powerful in due course. Consider that as it develops and elongates, it produces leaves the plant cannot survive without. The leaves are the powerhouses of any plant. Photosynthesis is the second most important biochemical reaction known (second only to enzymatic activity). Without photosynthesis, the plant starves and is unable to power any of its other metabolic processes. No hormones to produce roots or shoots. No enzymes to produce chlorophyll in order to support more photosynthesis. Nothing.
Leaving aside the rest of the negatives that go with lack of buds in the plant kingdom, not least of which is you and I would die, let’s focus on the raw power of the bud. As you might imagine, if each bud that appeared on a tree consisted of only one leaf the tree wouldn’t last long. Therefore each bud is a complex package, containing not only leaves – which appear readily as the bud opens – but also the entire vascular structure needed to transport raw materials to the leaves and food throughout the tree. Consider for a moment the collected deciduous tree consisting of only a trunk and severely pruned roots. The tree “knows” that without a branch structure supporting food-producing leaves it’s a goner. Therefore, the first order of business for the collected deciduous trunk is to grow new leaves and start making and transporting food; beneath the ground, it’s to grow the entire sub-surface support system that provides raw materials to the leaves. (The order in which this occurs varies from species to species; each knows what it has to do, however, regardless of the order.)
This is the American elm that appeared in the earlier post, in a photo taken March 7th. The buds on the tree at that time were very tiny – just big enough to be visible to the naked eye. Fast-forward a single week, and they’re beginning to move. Even at this early stage, you can see the extension of one of the buds. But what’s much more fascinating, at least to me, is the knowledge that this extending bud is programmed to become a mature branch with its own sub-branches and sub-sub-branches – what we in the bonsai world call ramification. I mean, consider the fact that all of this is programmed in right from the start. The bud doesn’t grow and then “learn” to get bigger and produce axillary buds; everything is already there, just waiting for signals from hormones to do their thing.
This process is reliable. The photo on the left was taken March 14th. Now our nascent shoot from last time has about half a dozen leaves (some are very tiny, waiting their turn to expand). It’s not a branch yet; that’s the next stage. Right now it’s very tender and easily damaged. It also has the ability to perform photosynthesis just as the leaves do. This ability only lasts until the shoot hardens off, at which time it will become brownish gray. But as with most plants that make their own food, there lies beneath the inner bark a layer of chlorophyll-infused tissue called the cambium layer of the plant. Whenever you use the “scratch test” to see if a branch is alive, you’re exposing a bit of the cambium layer – essentially it’s the presence of chlorophyll you’re seeking. If the branch dies, the chlorophyll degrades and turns brown (and dries out).
Notice that this shoot is stronger than the others. Whenever we chop an apically dominant tree, it’s only focus is to regain its height. This doesn’t work for the bonsai artist, meaning I can’t allow the strong shoot on this tree to become the dominant one. Once it hardens off sufficiently, I’ll trim it, wire it and bring it down into a horizontal position. This will automatically alter the dominance of certain hormones, allowing me to create an entire tree in just a foot-tall specimen.
I’ll post updates on this tree as it develops. This year I’ll be able to create the basic branch structure and get some secondary branching established. In 2016 the tree will be ready for a bonsai pot. By 2017 it should be a presentable American elm bonsai.