CHAPTER VIII. 



ESSENTIAL FLORAL LEAVES. 



MORPHOLOGY. 



The andrcecium and gyncecium may collectively be called the 

 essential organs, since they have to do with the formation of 

 seed. 



It is a familiar fact that, at certain times of the year, brown 

 patches appear on the backs of fern leaves. These are made up 

 of minute cases filled with excessively small brown grains. The 

 cases are termed sporangia, and the contained grains spores. 

 Club-mosses, common in mountainous districts, also produce 

 spores, and the yellow powder sold by chemists under the name 

 of lycopodium consists entirely of these. The bodies in question 

 can give rise to new plants under favourable conditions. 



Flowering plants also produce spores. Pollen is made up of 

 innumerable small grains which are of this nature, and every 

 ovule, as we shall see further on, contains a cell, the embryo sac, 

 which is also a spore. Since stamens and carpels produce these 

 bodies, they may be termed spore-leaves or sporophylls, and 

 from this point of view the flower may be defined as " a shoot 

 modified for spore- bearing." 



The stamens are termed male spore-leaves and the carpels 

 female spore-leaves. 



The Stamens, as we have seen in the buttercup, differ very 

 much from the typical leaf form. In the white waterlily, how- 

 ever, there are all possible stages between them and petals (fig. 

 39). On the other hand, no links connecting stamens and carpels 

 are found in normal flowers. 



Number and Arrangement. — In acyclic and hemicyclic flowers 

 a large number of spirally arranged stamens are found. An 

 instructive example of the former kind is seen in the Scotch fir. 

 The flowers of this plant (fig. 45) possess no perianth, and are 

 of two kinds — male, with stamens only, and female, with carpels 

 only. The ordinary " cones " are the latter, while the former are 

 much smaller, and crowded together into clusters. They are best 

 examined in June, when the pollen is ripe. Each one consists of 



