Vol. I: VIII. Botany for Painters and Elements of Landscape Painting: 403.
The Da Vinci Notebooks
The direction of growth (403-407).The plants which spread very much have the angles of the spaces which divide their branches more obtuse in proportion as their point of origin is lower down; that is nearer to the thickest and oldest portion of the tree. Therefore in the youngest portions of the tree the angles of ramification are more acute. 204
208:204 : Compare the sketches on the lower portion of Pl. XXVII, No. 2.