vertical growth
(from the article `tropism`) ...thigmotropism (response to mechanical stimulation), traumatotropism (response to wound lesion), and galvanotropism, or electrotropism (response to ...
orthotropism 1. An upward, or downward, vertical growth response or tropism of organs to a given stimulus. 2. A tendency to grow upward, or downward, in a vertical direction, in response to an orienting stimulus; such as, sunlight or gravity.
orthotropic tendency or growth.