That the bark of a tree has three very important and practical functions: It is waterproof, so it prevents leaking from the phloem; It also houses small structures, called lenticels, that allow the tree to breathe; and the bark's third function is to protect the phloem from all kinds of impacts, abrasions and attacks from pests; including: insects and fungi.
That wounds on bonsai trees do not heal in the same manner as the wounds of humans and/or animals. That is to say, trees are not able to repair damaged tissue; instead they continue to manufacture a new layer of cells with each years growth, until the wounds is entirely covered over. The length of time this 'healing' process takes depends upon the size of the wound and the overall size of each new annual growth ring.
That if you look at a cross-section of a tree trunk you will see rings and each of these rings indicates a full years worth of life and growth. Scientists can tell by the thickness or thinness of a ring in which year more rain and more subsequent growth took place. Accordingly, a thick ring indicates a year with more rain and more growth and thin ring indicates a year with less rain and less growth. This analysis is one method that curators of arboretums can use to tell when an injury occurred to an imported bonsai that is of an unknown age and approximately how many years it took for that injury to 'heal' or be completely calloused over. Scientific researchers and meteorologists can also use this method in their study of weather patterns from hundreds of years ago.
That mature trees, both bonsai and those on the front lawn, develop what is known as a 'collar' around the base of the largest branches. This swelling takes years to develop and is caused by the up and down, forward and backward, motion of the largest and heaviest branches as they are pushed to and fro by the whims of Mother Nature. These collars are important to those of us practicing bonsai cultivation, because they help to quicken the bonsai's healing processes by enabling wounds - specifically those wounds that are left after the pruning of large branches - to heal more rapidly.
DID YOU KNOW?
That the oldest bonsai in the national collection is over 300 years old. The bonsai is a White Pine that is affectionately known as the Yamaki Pine, in honor of its donor, Masaru Yamaki. The Yamaki began its life in the 1600s and, despite being less than five miles away from the impact site, it survived the atomic bomb blast at Hiroshima, Japan, in 1945.
That several of the bonsai in the national collection were given as gifts to various Presidents of the United States. In fact, in 1998, the Japanese Prime Minister, Mr. Obuchi, gave President William Jefferson Clinton an 80-year-old Ezo Spruce. The gift was truly significant to the national bonsai collection for two reasons: the first and most obvious reason is the fact that it is a masterpiece and the second, and lesser-known reason, is that the gift of an Ezo Spruce - any Ezo Spruce - to an American president is significant, because the United States maintains a long standing ban on the importation of all Ezo Spruce and, as a result, the national collection has been without an Ezo Spruce specimen.
That for many species of deciduous bonsai trees the size of the leaf is directly related to the type and amount of sunlight the tree is cultivated in. A bonsai that is grown in partial shade or in full shade will have longer and larger leaves, because the tree is trying to maximize the amount of sunlight it can absorb to enable it to continue its photosynthetic processes - a larger leaf has more surface area with which to gather sunlight. In contrast, a bonsai tree that is grown in direct sun, all or most of the time, will have smaller and more compact leaves, because it is receiving all of the sunlight it needs. As a result, it can devote its energy to growing. This is important for all trees, but more important for trees cultivated for bonsai, as smaller leaves are proportionate to the smaller scale of a bonsai tree; smaller leaves are, therefore, a positive trait, both aesthetically and from a horticultural perspective, because a tree is healthiest when it has access to all of the energy it needs to develop.
That an evergreen tree, such as a pine (black, white, red, scots pine, etc.) does not keep its needles for-ever. In fact, while evergreen trees do not shed their needles in a blaze of autumn splendor, along with the deciduous trees, every fall, they do replace their needles in two or three year cycles. Accordingly, evergreen trees remain for the most part, always green, because younger needles remain on the branch, as more mature needles are replaced.
