ancient plants are often used in woody sites, beside
streams and wet sites. Unlike higher plants, they do not
produce seeds but reproduce through spores borne on the
underside of the fronds (leaves). They drop to the
ground and, if given enough moisture, develop into a
multi-celled structure called a prothallus. It sends
rhizoids through the ground which act as "roots" to
absorb water and nutrients.
The prothallus eventually develops
male and female organs. Sperm cells swim in rain water
or dew to fertilize the egg cell in the female. This
grows into a sporophyte which then grows the typical
fern fronds and root system.
The spores are called fruiting bodies
and they are formed in clusters called sporangia.
Several of these cluster together to form a structure
called a sorus (plural son). The type and arrangement of
the son can be used to identify fern species.
Ferns also have various types of
and stems which may also be used in
identification. Some rhizomes creep under the ground and
new ferns emerge from the ground along their length.
Others like the Christmas fern have short rhizomes so it
appears that the new plants all emerge from a central
crown. Small parts of the frond called pinnae also
differ widely from one fern species to another.