376 STRUCTURE AND LIFE HISTORIES 
The life history of Equisetum may be tabulated as 
follows: 
OUTLINE OF LIFE HISTORY OF EQUISETUM 
Rhizome 
4, 4 ! Sporophyte 
Sterile branch Fertile branch 
44 
Strobilus 
44 
Sporangiophores 
44 
Sporangia 
Reduction 
Isospore Isospore 
\~ -\~ 
Male gametophyte Female gametophyte 
4 4 
Antheridium Archegonium 
4 4 
Sperm Egg 
^Fertilization 
^ ^ 
Oosperm 
44 
Embryo 
44 
Mature sporophyte 
H. THE CLUB-MOSSES (LYCOPODIALES) 
LYCOPODIUM 
337. Habitat and Distribution. Nearly all the species 
of Lycopodium prefer moist situations, and one or two of 
them are aquatic. They are widely distributed over the 
earth, in both hemispheres, from the torrid to the frigid 
zones, and commonly grow in shady places. Lycopodium 
Selago, and a few other species are epiphytic. They all 
