10 



THE FLOWER GROWERS GUIDE. 



many of the seaweeds and fresh-water algoe are aquatic, and some kinds appear to 

 be self-luminous, while others possess the unique power of developing chlorophyll or 

 leaf-green, though growing in dark places. 



Though ferns, mushrooms [Fungi)., and other cryptogams have no flowers in the 

 ordinary sense, yet they possess organs analogous to flowers, and which perform 

 similar functions in the perpetuation of the plants. You all know the clusters and 

 lines of "spores," easily seen on the backs of most fern fronds. These clusters 

 and lines really consist of groups of spore-cases (example 3 in the illustration opposite). 

 When these cases are ripe they are hygrometrical, and burst open during wet or damp 

 weather, and so liberate the spores. These spores then fall, or are blown or carried 

 on to damp tree trunks, rocks, or soil, and begin to grow or germinate as shown in 

 example 4. No cotyledons are produced as in the case of seeds, but merely a dark- 

 green flat growth of cellular tissue called a prothallus, or first expansion (see Fig. 1 

 in the group). 



On the under-surface, or at the back of the prothallus, organs analogous in a sense 

 to flowers are formed. These are the antheridia, or male organs (analogous to the 

 pollen of flowers), and the archegonia, or female organs, analogous to the ovary or 

 seed vessel in flowering plants ; so that fertilisation takes place in cryptogams after the 

 germination of the spores. Spores, unlike seeds, have no cotyledons and are asexual 

 (= vegetative) bodies with powers of cellular germination. 



The fertilisation of flowers, however, takes place mostly in dry weather, but that of 

 the flowerless plants is only possible during wet weather, which is the reason that 

 all fungoid pests, such as the vine mildew, the potato, tomato, and other diseases of 

 the same nature, increase most rapidly during warm wet periods in autumn. 



On the back of the prothallia both antheridia and archegonia are formed when 

 ripe, and fully-formed zoospores or antheridia are set free. These are spiral bodies 

 furnished with eyelash-like cilia (example 5), which enable them to gyrate or twist 

 themselves forward very rapidly in water, or on the dewy surfaces of leaves. 



The female organs, or archegonia, are small raised bosses ; a section is shown of 

 one of them in example G. There is a small pore or mouth-like opening, and a sort 

 of a nucleus at the base of the orifice as shown. The prothallia are generally bathed 

 with moisture, and by means of this as a medium the lively little antherozoids are 

 enabled to enter the archegonium in the direction of the arrow, after which fertilisation 

 is effected and young fronds appear as in example 2 in the group on the next page. 



