6o 



Commercial Gardening 



are obtainable, or might not come true to the parent, and in the case of 

 choice and rare ferns may be the only means cf perpetuating them. 

 None of the above processes gives rise to a new individual, but merely 

 young or rehabilitated pieces of the old ones, and this is what vegetative 

 reproduction implies. [j. F.] 



9. THE FLOWER AND ITS FUNCTIONS 



The Parts of a Flower. Phanerogams, or flowering plants, differ 

 from Ferns and other vascular plants in the great modifications which 

 the leaves have undergone in the construction of the flower. A complete 

 flower consists of four sets of organs, termed respectively the calyx, 

 corolla, stamens, and pistil. Each member of these sets 

 or whorls of organs consists of a leaf, modified according 

 to the function which it has to perform in the economy 

 of the plant. The axis bearing these floral leaves ceases 

 to lengthen when the flowering stage of the plant has 



been reached. 



1. The Calyx. The number of 



parts forming the calyx varies, but 



four (as in the Wallflower) and five 



(as in the Buttercup) are extremely 



common numbers. These parts are 



situated on the outside of the flower Fi - 48 - - campanula 



- , r . /. Flower, showing a regu- 



proper, and when tree irorn one an- i ar flower with flve- 

 other are termed sepals: but when Pf te , d c , alyx and corolla - 



The leaf on the pedicel 



Fig. 47. Strawberry 

 Flower 



p, petals ; , sepals. 



is called a bract. 



more or less united they are described 

 as the segments, lobes, or teeth of the 

 calyx, according to the length of the free portion. Usually they are small, 

 green, and serve to protect the other parts of the flower. In the Christmas 

 Rose (Helleborus niger), Marsh Marigold (Caltha), Delphinium, and Aconi- 

 tum they are large, highly coloured, showy, and perform the function 

 of the corolla in attracting insects. 



2. The Corolla. The second set of organs, proceeding inwards, con- 

 stitutes the corolla; and, if the parts are free, they are termed petals, 

 as in the Buttercup, Rose, Camellia, Sweet Pea, and Strawberry (fig. 47). 

 Very often all the pieces are united for a greater or less part of their 

 length, when the corolla is said to be gamopetalous, as in the Primrose, 

 Salvia, Dandelion, Stephanotis, Gardenia, and Campanula (fig. 48). The 

 lower part of these flowers is the tube and the expanded portion the limb; 

 the latter is often two-lipped, as in Salvia and Lamium (fig. 49, l). The 

 corolla is bell-shaped in Campanula, funnel-shaped in Convolvulus, and 

 so on. It is usually the most showy part of the flower, protecting the 

 inner parts, but designed more particularly to attract and guide insects 

 to the nectar. In the Christmas Rose, Winter Aconite, and Globe Flower 



