vi] ABOUT A FERN. 103 
thallus develops reproductive organs which, instead of 
producing other prothalli, give rise to a true fern like 
that which produced the spore. In this lies its chief 
difference from a seed, for a seed produces a plant 
exactly resembling that which produced the seed. 
And now it grows vigorously and sends up frond 
after frond, until the stem becomes thick and the 
fronds long and spreading, and bear upon their under- 
surface spore clusters, like those we have before 
alluded to. These spores afford the surest method 
to the tyro for detecting ferns, as no other plants 
produce spores in the same manner. The leafy 
portion of the fern is known as a frond, but it differs 
considerably from the leaves of flowering plants. In 
the latter the point, or apex, of the leaf is first formed, 
the leaf-stalk last. In the fern the leaf-stalk is formed 
first, and the apex the last. 
If we examine a growing plant of the Common 
Bracken-fern (Péeris aguilina) we shall find it to 
consist of an underground creeping stem giving off 
rootlets below and fronds above. In this case the 
stem is called a rhizome, because of its creeping 
underground, but if we take the Common Male-fern 
(Lastrea filix-mas) we shall find that the stem, 
instead of taking a horizontal direction, as in Bracken, 
is perpendicular, and the upper end is above the 
sround. In this case the stem will be termed a 
caudex, and a more noticeable example of it will be 
found in the arborescent stems of the Tree-fern ‘of 
Australia, &c. It should be noticed that the fronds 
arise, not from the growing point of the stem, but 
from certain points at a greater or lesser distance 
