By Enrique Castaño, Mexico
2010 John Y. Naka Award Winner

Species of bonsai: Avicennia germinans
Common name of tree: Black mangrove
Source of bonsai material: collected
Years in development from stock: 4
Starting height: 112 cm (43 inches)

Black Mangrove, Avicennia germinans, is a good species for bonsai.

Despite its common name, this is the lightest in color of the mangroves. Black Mangrove has opposite leaves, pale gray-green that can become almost white, which is also why it may be known as white buttonwood. The leaves are shiny above, and often found encrusted with salt. The leaves are usually larger than most mangroves at 4.5 to 15 centimeters (two to six inches) long and are oblong to lanceolate in shape. However, they can be reduced to ½ cm or less if the branches are constantly pinched. The tree can grow up to eight meters (24 feet) in high. The flowers are small — 0.2 centimeters (1/8th of an inch), white to yellow in color, and blooms from November to May. The fruit is about one centimeter (0.5 inch) in length and irregularly oblique shaped. Black Mangrove is one of the few mangroves that don’t grow on stilt roots. The root system consists of long underground cable roots that produce hundreds of thin, upright pneumatophores in the water around the tree. These structures have numerous pores that are thought to conduct oxygen to the underground portions of the root system. This tree is particularly strong and cuttings will take very easily, I have yet to see someone use it for bonsai. In March 2007, I was passing through an area near the coast of Tulum, Mexico, about 300 miles from my home and I saw a lot of dead trees. Most of them had great movement and the white dead wood was incredible. I decided I could use some for tanukis or just simple Ikebanas. Of course, I had to get into the mud and get soaked. It was however a sad site, as I could see hundreds of dead trees with many more following the same trend. As I was passing I saw a few that were still slightly alive, so I decided to collect them. This particular Avicennia had a great lifeline and interesting deadwood that needed just a bit of work. But first, the health of the tree had to be established. The soil in which they were living is only a 30 cm deep and contained almost no useful nutrients, with high salinity and no air. Although the species is very tough, few plants in the world would survive such conditions. Also, having been exposed to hurricanes over the decades prevents any tree from growing very tall and the constant currents of air will kill sections of the trees. The high salinity in the mist covers the wood, giving it a white appearance and preventing it from rotting. A few weeks after collection the tree’s health was much improved. New growth came quickly and most importantly new roots were beginning to form. I had chosen a soil that contained a rough structure and a lot of volcanic rock that would keep a lot of humidity but provide more air for the roots. Many times beginners and non-practitioners of the art think that bonsai artists want the trees to grow slow. Quite the contrary, the faster it grows the faster one can shape it. Using the right growing conditions and knowing them gives the artist the plasticity to think what to do. One can follow simple rules and that’s fine but one has to know what the time frame would be to have the tree look decent.

The tree had lots of potential, the last few months had allowed the tree to grow a new root structure, and increase its health, The tree was ready to be worked on. The suckers at the base of the tree were growing too fast (Figure 1). One or two years more and the rest of the trunk would die and these straight suckers would be the only thing left of this old tree. So I removed them, and also removed those branches that were in the way. I was getting a clear picture of the tree after this first branch selection (Figure 2 and 3). Once the problems are identified the next step was to select the order of correcting the problems. One can start with wiring the tree or potting the tree in its new container. But I decided to wait! It was obvious to me that I couldn’t start working of the tree at this stage, because wiring would slow growth for a few weeks and the same with repotting. Also, I needed secondary and tertiary branches in a few weeks to force the tree to use the new roots that it had grown to feed the upper part of the tree, knowing that once the suckers were removed the tree would grow quickly. So for a few weeks, the tree was allowed to grow while removing any suckers that appeared. This would strengthen the life vein and a little bit of the dead wood was cleaned and carved. Once the new growth came out and a few more branches were developed, I decided to place the tree in its new pot. The pot came from my travel to Czech Republic in June and I had selected it for this tree in particular. More than thinking of contrast I decided to go with similarity of colors and the matt glaze of this pot. However, after removing the soil I found that the taproot was longer than needed. I cut it in half and took some of the center part so it could be bent and the tree was moved down about 10 cm (Figure 4). This was enough to provide a good visual height of the tree with respect to the pot. The tree was secured with wire (Figure 5). Although it doesn’t show after potting, I usually don't like to see that wire being exposed!

The soil mixture allowed a fast drainage but at the same time it contains some organic matter from added granular soil. To keep the tree in good health, more than 70 percent of the leaves were removed. This will prevent dehydration from some of the fine roots that were removed during this process. This also initiates lignification on the branches and a hormonal signal that new branches need to be created. Therefore wiring of the main branches had to be done before they would become brittle and break easily. The main line of the branches was generated and the rest was simply to wait for the tree to get adjusted to its new environment. After the branches grew several more leaves the tree was ready to be completely wired and proper placement was set to provide a simple almost umbrella shape. Also more carving was done and the wood was protected with lime sulfur, providing the typical whitish color seen in the deadwood of this species. A comparison can be made from the trees before and after (Figures 6 and 7).

A month after the event, the tree continues its growth obviously slowing down in growth as the temperature goes down. I will have it on display this year at the annual exhibition in Merida (Mexico) if anybody its interested in seeing this and other Avicennias.