How to know the ferns

by Frances Theodora Parsons

Fig. 1, Fig. 2, Fig. 3

A frond is simple when it consists of an undivided leaf such as that of the Hart's Tongue or of the Walking Leaf ([Fig. 1]).

A frond is pinnatifid when cut so as to form lobes extending half-way or more to the midvein ([Fig. 2]).

A frond is once-pinnate when the incisions extend to the midvein ([Fig. 3]). Under these conditions the midvein is called the rachis (a), and the divisions are called the pinnæ (b).

A frond is twice-pinnate when the pinnæ are cut into divisions which extend to their midveins ([Fig. 4]). These divisions of the pinnæ are called pinnules (a).

Fig. 4