174 NEW ZEALAND PLANTS. 
together with their allies the club-mosses (Lycopodium), and Tmesi- 
pteris, Psilotum, Isoetes, Pilularia, and Azolla, contain more than 
150 species. 
The ferns (Filices) bear their spores in little stalked bags, called 
sporangia, groups of which are plainly visible as circular brown 
patches or spots upon the back of the leaf. In some ferns—e.g., 
the hard-ferns (Blechnwm)—only certain leaves bear spores, and 
these in that genus are of a different shape and narrower than the 
leaves without spores. In other ferns again—e.g., the moonwort 
(Botrychium) and the adder’s-tongue (Ophioglossum)—there are also 
spore-bearing and sporeless leaves, very different in appearance, but 
both are given off from the same leaf-stalk. By some the two latter 
genera are not classed with the true ferns. 
_ When a spore germinates it does not give rise to another fern- 
plant, but to a small, flat, green body, frequently heart-shaped (the 
prothallus), which in course of time produces on its under-surface 
reproductive organs, so that an act of fertilization can eventually 
take place. By this means a young plant is produced which eventu- 
ally grows into an ordinary spore-bearing fern. 
New Zealand ferns are divided into 33 genera, one of which 
(Lozsoma) is endemic. The genera containing the most species are 
the filmy ferns (Hymenophyllum), the hard-ferns (Blechnum), the 
spleenworts (Aspleniwm), and the polypodies (Polypodium). 
Generally the leaf-surface of a fern is more or less vertical, but 
in the genus Gleichenia it is horizontal, whence the species of that 
genus get the name of “ umbrella-fern ”’ (fig. 97). 
The beautiful filmy ferns belong to the genera Hymenophyllum 
and Tvrichomanes. The leaves of these ferns are generally much 
divided, but those of the kidney-fern (Trichomanes reniforme) have 
a quite even margin. Many ferns can live only in a moist atmo- 
sphere ; others, again, can tolerate extreme drought—e.g., the thick- 
leaved Cyclophorus serpens and the woolly Gymnogramme rutaefolia. 
The club-mosses (Lycopodiaceae) are represented by 11 species, 
one of which, ZL. ramulosum, is endemic. Although called “ club- 
mosses,” they bear no relationship to mosses proper. Like the 
ferns, these plants pass through a sexless (spore-bearing) stage and 
a sexual stage. The latter does not consist of a flat body which 
lives on the ground, &c., as in the ferns, but of tiny “ tubers,’ which 
have to be dug out of the ground, in appearance something like 
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