The elm: why upper branches lengthen and lower ones die
Red-chalk elm studies with notes on how the highest shoots grow and the shaded lower limbs dry
A page devoted to the elm, with red-chalk studies of its bare branching drawn at the right. Leonardo observes that the elm always puts greater length into the topmost branches of a given year than into the lower ones, because the higher branches are the ones that must enlarge the tree while the lower ones must dry up: kept in shadow, their growth would only block the sun's rays and the air from entering among the tree's master branches. A second note adds that the lower master branches bend more than the upper ones because they are more oblique, larger, and older, and because they seek the air and flee the shade.
On this page
The elm lengthens its topmost year-branches and lets the lower dry
The elm always puts greater length into the last branches of the same year than into the lower ones. The higher branches must increase the size of the tree, while the lower must dry up, for they remain in shadow and their growth would hinder the entry of the sun's rays and of the air among the tree's master branching.
Why the lower master branches bend most
The lower master branches bend more than the upper ones, being more oblique than those above, and also because they are larger and older, and in order to seek the air and to flee the shadow.
Red-chalk studies of an elm's branching
Bare elm branches are drawn in red chalk at the right of the page, illustrating the long upper shoots and the more sharply bent lower limbs described in the notes.