In the Spanish chestnut, and in certain fir-trees, the angles of divergence of the leaves differ, according to Schacht, in the nearly horizontal and in the upright branches.

In the common rue and some other plants, one flower, usually the central or terminal one, opens first, and has five sepals and petals, and five divisions to the ovarium; while all the other flowers on the plant are tetramerous.

In the British Adoxa the uppermost flower generally has two calyx-lobes with the other organs tetramerous, while the surrounding flowers generally have three calyx-lobes with the other organs pentamerous.

In many Compositae and Umbelliferae (and in some other plants) the circumferential flowers have their corollas much more developed than those of the centre; and this seems often connected with the abortion of the reproductive organs.

It is a more curious fact, previously referred to, that the achenes or seeds of the circumference and centre sometimes differ greatly in form, colour and other characters.