97 
Ceratopteris thalictroides y ( L .) 
his ‘ Species Filicum V describes the sterile leaves as being 
simple or more or less divided when young, the older ones 
being bi-tripinnate and much dissected. All the first leaves 
which are borne by a young Ceratopteris plant are sterile, the 
fertile leaves do not arise until much later. The leaves on 
a young plant have been described and figured by Kny 2 , the 
first being simple and spatulate in shape, whilst somewhat 
older ones are irregularly trilobed. At a later stage the first 
compound sterile leaves are found (PI. VI, Fig. i). The 
individual leaflets, which vary in number from three upwards, 
are sessile on each side of the main rachis, and are themselves 
irregularly trilobed. The fertile leaves arise at a much later 
stage than the sterile, but both kinds are present at the same 
time. The fertile leaves are generally taller than the sterile, 
their lamina is reduced, the leaves being much dissected with 
narrow linear segments. The sporangia are scattered singly 
on the under surface, and are never united into sori. No true 
indusium is present, but the edges of the leaves curve over 
and enclose the sporangia, forming a false indusium. The 
sporangia are spherical with a short stalk, and are always 
situated over a vein. 
Large numbers of vegetative buds are found occurring on 
the sterile as well as on the fertile leaves. These buds arise 
at the angles of the leaf-segments, and sometimes grow to 
a considerable size before becoming detached from the parent 
plant. In some material from the Botanical Gardens at 
Cambridge, vigorous young plants of Ceratopteris with several 
well-developed leaves were found still attached to a dead and 
blackened leaf of the original parent plant (Fig. 2). These 
vegetative buds are found on the sterile leaves of quite young 
and immature plants ; on one measuring 3-4 inches in height 
three were counted on a single leaf. 
The leaves of a mature Ceratopteris plant are furnished with 
stout petioles, which surround and often completely hide the 
reduced and, comparatively speaking, insignificant stem. In 
looking at a plant from below, a curious tri-radiate arrange- 
1 Hooker, 1858, p. 235. 2 Kny, 1875, pp. 42 and 43. 
H 
