OTHER FERN-LIKE PLANTS: CLUB MOSSES 377 



They are frequently called " ground pine," and are often collected 

 for holiday decorations. The branching of the stems is usually 

 forked. Prothallia are not known in northern countries, but have 

 been found for several species in tropical countries. In one of 

 these (L. cernuuni) the prothallium is a cylindrical body, sunk in 

 the earth, with green lobes at the top where the sexual organs are 

 developed. In others the prothallium is a slender, colorless, 

 branched body, growing saprophytically in the decaying bark of 

 trees. With some of these a fungus is associated, making a 

 structure similar to certain mycorhizae (paragraph 206). In 

 northern countries where prothallia have not been discovered, the 

 species propagate by vegetative growth, and some by bulbils, as 

 in the case of L. lucidulum. These bulbils are specialized buds. 



530. The fruiting spike or strobilus. The spore-bearing 

 leaves (sporophylls) are grouped into a cylindrical spike (a stro- 

 bilus) at the end of the stem where they closely overlap. At the 

 base of each sporophyll is a spore case containing many small 

 spores. These are shed by the spore case splitting transversely. 

 The spores are produced in great quantity and are pale yellow- 

 ish in mass. They are sometimes used for various toilet pur- 

 poses, for pyrotechnics, and for coating certain pills to prevent 

 adhesion. 



531. The little club mosses (Selaginella). Some of the 

 species of Selaginella in northern countries resemble Lycopo- 

 dium, and are sometimes called " little club mosses" because they 

 are much smaller in size. The leaves are crowded on the slender 

 stems and in many species are arranged in four or six rows. 

 The stems of many species are dorsiventral, the rows on each 

 side being approximated, giving a flattened appearance. Many 

 of the tropical species are quite large, and are grown in green- 

 houses for ornament because of the beauty of their form and the 

 metallic colors of some species. They are branched profusely, 

 often in a single plane, thus giving the appearance of a large leaf. 

 One of the tropical species is known as " resurrection " plant, or 

 " resurrection " moss. When it dries it rounds up in a ball. 

 The roots are thus drawn from the soil, and it is often rolled 



