424 THE VASCULAR PLANTS 



rangia. When the sporangia are ripe, the leaves which bear 

 them separate and the spores escape. Since these peculiar 

 leaves are exclusively devoted to spore production they are 

 called sporophylls. You will find the word sporophyll of 

 much importance from this time on. It is applied to any 

 structure, leaf-like in origin, whose main business is the bearing 

 of spores. 



There are some of the true ferns which also produce their 

 spores on special leaves or special parts of leaves instead of 

 on the under surface of the ordinary leaves. Botrychium 

 is an example. (See Figure 216.) 



The cone-shaped aggregation of sporophylls which we 

 find in equisetum is called a strobilus, and this word too 

 you will find to be important from this time on. Any group 

 of sporophylls growing close together is called a strobilus, and 

 it is from strobili that flowers have evolved. From what you 

 already know you can see that stamens and carpels are 

 sporophylls; i.e. they are leaves as to origin and they 

 produce spores. 



78. Club Mosses (Lycopodiales.) — This is the third 

 division of pteridophytes. Some of the members of it are 

 called ground pines. They grow in pine forests and hjlve 

 a resemblance to seedlings of pines. They are often used 

 for Christmas decorations. They have long stems which 

 spread over the ground. Their leaves are small, numerous, 

 and scale-hke. (See Figure 2iy.) 



The leaves which bear the sporangia of these plants are 

 usually those near the tips of the stems. The sporangia 

 appear on the upper surfaces of the leaves near the axils, 

 and there is only one to a sporophyll. (You recall that in 

 ferns the sporangia are many and on the under side of the 



