Garden with Insight v1.0 Help: hormonal gradient

One of the most fascinating things about plants is their modular organization. We have cells and organs, but very little repetition. One could argue that a plant is as close to being a population as it is to being an organism. Each component of a plant -- the stem internodes, the leaves, the meristems (buds) -- communicates with other parts mainly by exchanging molecules. Plant hormones are substances put out by certain parts of the plant specifically to communicate messages to other parts of the plant. As these plant hormones move away from their source, they spread out and decrease in concentration, creating a hormonal gradient. Scientists have studied some plant hormones, but there is still much to learn about this subject.

One example of a plant hormonal gradient is the one involved in apical dominance. Apical dominance is a phenomenon where the apical meristem on a branch (at the tip of the branch) puts out a hormone that tells all the axillary (side) meristems on the branch not to develop. This keeps the branch from making any other branches. When a plant needs to increase its height to capture sunlight, apical dominance allows it to concentrate its resources in lengthening its main stem. If you cut the apical meristem off a branch, some of the axillary meristems along the branch start to develop because the hormonal gradient decreased.

How it works:
apical dominance