376 STRUCTURE AND LIFE HISTORIES 



The life history of Equisetum may be tabulated as 

 follows: 



OUTLINE OF LIFE HISTORY OF EQUISETUM 



Rhizome 1 



4, '\, \ Sporophyte 



Sterile branch Fertile branch J 



li 



Strobilus 



ii 

 Sporangiophores 



4,4, 

 Sporangia 



Reduction 

 Isospore Isospore 



i i 



Male gametophyte Female gametophyte 



i i 



Antheridium Archegonium 



4, 4^ 



Sperm Fertilization Egg 



Oosperm 



ii 



Embryo 



ii 



Mature sporophyte 



n. THE CLUB-MOSSES (LYCOPODIALES) 



LYCOPODIUIVJ 



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 



