14 
Colorado Experiment Station 
and are leaf-like. There is a form of lichen in our mountains which 
hangs in gray-green moss-like masses from the branches of the ever¬ 
greens. Lichens have a great range of color: orange, yellow, green, 
gray, brown, and black. They are composed of certain algae and 
fungi growing in intimate relationship. Lichens, as a group, with 
stand drying very well, and have remarkable powers of recovery 
when moisture becomes available. 
None of the lichens are known to poison stock. It is quite likely 
that some of the leafy sorts are eaten to a slight extent. 
MOSSES 
Mosses are familiar to all. They are not as abundant under the 
dry atmospheric conditions of Colorado as in moister sections of our 
country, d'hey are the best developed in the mountains, especially 
along streams and in shaded situations. None of the mosses are 
CD 
kno^vn to be, or suspected of being, poisonous to stock. 
FERNS 
Colorado does not possess a large variety of ferns; further¬ 
more, they do not grow in such luxuriance here, as in the damjp, 
moist woods of the eastern states. 
Ferns have underground stems that run horizontal to the soil 
surface. They spread by means of these stems, and also by means of 
spores. The spores are formed on the under side or margin of the 
frond (leaf). These spores occur in reddish-brown masses (fig. 4). 
The only fern iii Colorado that is suspected of being poisonous 
to stock is the brake-fern (Pteridium aquilinum) (fig. 5). This 
plant has widely-spreading, blackish rootstocks. The leaves are two 
to three feet long, and divide into three main divisions, each ot 
which is again subdivided. 
EOULSETUM: HORSETAIL, SCOURING RUSH, JOINTED 
GRASS 
There are several species of Equisetum growing within Colo¬ 
rado. The two most common ones are the Common Horsetail (Bqui- 
setum arvense), and the Smooth Scouring Rush {Bqtiisehim laevi- 
gatiim'). Both are rush-like perennials from underground rootstocks. 
They have rough, jointed stems that are closed at the joints. The stems 
are marked with a number of grooves that run lengthwise. At the 
joints are small, pointed leaf-like structures, the sheaths. All horsetails 
and scouring-rushes have harsh, rough stems, due to deposits of silica 
(sand) within. 
The common horsetail (figs. 6 and 7) (Bqnisetuin arvense) dies 
down to the ground each year. It has two kinds oif stems. In the 
early spring there are sent up from the underground rootstocks, sim¬ 
ple, unbranched jointed stems, which bear a spore-bearing cone- 
shaped organ at the top (fig. 6). These die down after spore pro¬ 
duction, and are followed b}^ slender, solid, 4-cornered stems that 
send out numerous branches at the joints (fig. 7). The common 
horsetail is found throughout the state, from the plains up to as high 
