214 
HISTOHY OF BRITISH FERNS, 
phosed terminal bud of a main axis, and the smaller 
granules, as lateral buds, or twig buds, only to be distin- 
guished from the terminal bud which is developed into the 
oophoridium, by the circumstance that the latter is a prin- 
cipal branch, possibly capable of a more extensive develop- 
ment into branch and foliaceous organs ; while the twig, 
which is developed into an antheridium, is but a small 
particle of such a main branch. 
These plants, like the Ferns, are most abundant in hot, 
humid, and especially insular situations in the tropics, 
becoming scarcer northwards, but often, even in very 
northerly regions, covering large tracts of land. Our native 
species, with one exception, have a boreal and alpine ten- 
dency ; being found most abundantly on the high lands of 
the north, and decreasing in quantity as they advance 
southwards. Many of the tropical Lycopodiums are ex- 
tremely beautiful : some are of scandent habit, and many 
of them attain considerable size. 
Though of humble growth, and altogether unattractive 
in appearance, the Club-mosses are not without their use. 
More than one species is used in dyeing operations, and 
several have a medicinal reputation. The powdery spores, 
often called pollen, produced in considerable quantities by 
