203 
BRITISH FERNS. 
from 8 to 10 inches long, is jointed, the joints furnished 
with four or five sharp teeth. The colour of the whole 
frond is a pale green, and attains a height of from 6 
to 8 feet. The fertile stem appears in March, and 
ripens its cone in April, disappearing a month or six 
weeks later. It only grows from 8 inches to 1 foot in 
height. The stem is divided into about fifteen joints, 
the sheaths are large, loose, and pale, as well as the 
stem ; the teeth long and slender, equal in number to 
those on the barren stems. The cones are very large, 
often 2^ inches long, and 1^ in circumference; the 
scales are very numerous, and the capsules attached to 
them are arranged in whorls. The stem is simple, and 
destitute of branches. 
A section of the stem shows a narrow cylinder and 
large cavity; the exterior surface scarcely exhibits any 
difference between the slight ridges and furrows, but it 
shows two circles of openings, or stomata, those of the 
exterior large, and those of the interior small and al- 
ternating with the larger ones. 
This handsome Horsetail is pretty frequent in watery 
places, besides rivers and ditches, in England. It is 
also found in India, North Africa, Canada, and the 
United Stages. 
59. Eqmsetum umbrosum, Meyer and Willd. Blunt- 
topped Horsetail. 
Caudex long, dark-coloured, creeping, and bearing whorls of 
slender roots. Barren stem terminating abruptly. Branches 
simple, in whorls. Fertile stem simple. 
The Blunt-topped Horsetail has stems of three kinds. 
The barren stem has from eighteen to twenty sharp 
