- Written by Kevin R. Lee Kevin R. Lee
- Published: 14 November 2019 14 November 2019
Buds, Roots , Mycorrhizae:
Lets take a closer look at some of the early growth and start up actions; one of the most interesting is the buds.
Trees do not rush into a panic when spring conditions seem to magically appear. Indeed, this spring's preparation began last spring, and this happens each year. As soon as a terminal bud is activated and begins its year's work, a good portion of that work goes into building the tissue that will be in place for the following spring.
The first thing to do once the weather warms up is to shed the winter coat. The bud cap or scales are a layer of tough, very tight fitting armor that effectively keeps at bay the worst that winter has to offer. Inside the buds are the tiny first leaves, flowers and apical meristems, the shoot in miniature, just waiting for exposure to the sun. Flower buds are a separate tissue and depending on that specific tree's designs will be deployed as planned, some before the early leaves, some with the leaves and some after.
There is now a flurry of activity at the branch tips; the flowers and leaves unfurl and the shoot begins to stretch and gain some length. The shoot quickly begins to form a new terminal bud, which is the start of the whole process for next year. Other preparations for next year are the newly forming buds in the axis of each set of leaves and lateral shoots. The shoot literally stretches as it grows, and the new terminal buds are always at the tip, growing, forming, maturing for its work next year.
For now, that is a good overview of the action at the branch tips. Let's go all the way down to the other end of the tree, underground, the root system.
Like a beautiful picture of a glassy mountain lake reflecting in reverse the scene above, that lake surface can be compared to the surface of the earth, and in reverse we see the trunk splitting again and again to finally get to the smallest roots, which are the complementary parts of the leaf clusters far above.
Let's move around a bit and look at what those other parts of the tree's body are doing. Farthest away are the root hairs, the furry miniature fingers covering the surface of all the tiny roots that are about the diameter of our hair. Think of all that surface area in place to interact with the soil and water and essential elements that the tree requires for a good life. There are 17 essential elements: three of them, carbon, hydrogen and oxygen are derived from the air and water. The other 14 are taken up from the soil as ions.
Thinking of all that surface area that the tiny root hairs have in the soil is amazing, but it gets better. We can jump to a whole different level when we include the mostly microscopic fungal life called mycorrhizae, a word that literally means fungus root. There are two main types: those that have most of their tissue outside the root hair and those that have it inside the root hair. Mycorrhizae greatly increase the tree root's ability to take up a variety of elements, especially copper, manganese, phosphorus and zinc.
You can imagine, especially in a forest with a lot of trees of the same species, that it all becomes one massive living, interconnected network, a network that responds to the needs of individuals and gives them water, energy, sugars, help when needed. Yes, we still have a lot to learn from trees.
The rest of the root system is as complex as the tree above it. Tree roots grow, divide and expand much like their counterparts up in the light. Older woody roots have a type of bark tissue and also experience yearly incremental growth, very similar to the branches and trunk above. This growth is more measured than the growth rings in the trunk, but it is there nonetheless. The surface of woody roots is tough and waterproof, so as to avoid loss of the precious water and nutrients once they have been taken up by root hairs and are in the system and on their way up to the leaves.