Note 11 — FLORA OF THE PRIMARY OR PALÆOZOIC PERIOD.
Reading edition
Conjugate spirals result from whorls of usually 2, 3, 5, 8, etc., leaves arranged so as to give 2, 5, 8, etc., parallel spirals, each with an angular divergence equal to ½, ⅓, ⅕, ⅛, etc., of one of the fractions expressing the divergence in an arrangement of alternate leaves.