THE LIVERWORTS 117 



Several of the commonest feather-mosses are shown in our 

 plates, made from photographs. 



The Liverworts grow in the same kinds of habitats as the 

 mosses, but on the whole are more decidedly moisture - loving 

 plants. 



The commonest and most easily recognised of our liverworts 

 is Pellia epiphylla, which grows chiefly beside streams. Almost 

 any stream will yield abundant material, and Pellia is an ex- 

 tremely interesting plant on which to make continuous observa- 

 tions throughout the year. It can easily be grown indoors, kept 

 moist in flat dishes. It forms patches, sometimes a foot or more 

 across, in which the plants overlap each other, the new branches 

 growing over the old ones so as to form a felted mass. The 

 plant consists of a branching green ribbon or thallus, which has 

 a thick middle part or " midrib/' and is covered below with 

 brownish rooting-hairs given off by the midrib. In early spring 

 the growing ends of the thallus have a crisp parsley-like appear- 

 ance, due to the young branches, which have a bright fresh green 

 colour. Later, these grow out and form the new ribbon-like 

 lobes. About this time (April or May) the plants often show the 

 fruits. These are stalked capsules, the stalk being long, slender, 

 and delicate in texture, while the capsule is spherical and black. 

 Since each branch may produce a fruit, the appearance of a 

 fruiting patch of Pellia is very striking, the plants appearing to 

 be studded with long black-headed pins. If you pull up a patch 

 before the fruits have grown up, and keep it under observation 

 indoors, you will find that the stalk is at first very short, and 

 that the fruit lies inside, or just projects from, a cavity in the 

 thallus. The fruits can be found during the winter months, 

 each sheltered in its pocket-like cavity, which has a little flap 

 over the opening. In spring the stalk grows in length, carrying 

 the capsule upwards. This growth is usually very rapid, and 

 the stalk may reach a length of four inches (i.e. forty or fifty 

 times its original length) in three days after it has begun to 

 elongate. The capsule then splits into four pieces, exposing a 

 mop-like mass of spores mingled with threads (elaters). The 

 elaters wriggle about with every change in the moistness and 

 dryness of the air, and thus loosen the spores, which are dispersed 



