The Science of Plant Growing 



61 



(Trollius), the petals are small and modified to form nectaries, and this 

 would explain why the sepals are large and highly coloured. The modi- 

 fications are endless, and usually have some reference to the method of 

 fertilization. The corolla is said to be regular when all the parts are 

 alike, but irregular when they are of different sizes, shapes, or disposition, 

 as in Salvia, Snapdragon (fig. 49, J), or Sweet Pea. 



Fig. 49. Forms of Corolla 



A, Cruciate. B, Caryophyllaceous. c, Papilionaceous. D, Tubular. E, Campanulate. F, Funnel-shaped, 

 o, Rotate. H, Ligulate. I, Labiate. J, Personate. K, Personate and spurred. L, Nectaries. 



In many flowers the outer and inner whorls, representing calyx and 

 corolla, may be of the same texture and colour, and in such cases they 

 are collectively termed the perianth, as in Daffodils, Lilies, Amaryllis, 

 Tulips, Crocuses, Irises, and other Monocotyledons. In many Dicotyledons, 

 however, there is only one set of organs, which may be green or coloured, 

 and the term perianth is also applied to them, as in Daphne, Marvel of 

 Peru, Knotweeds (Polygonum), and Docks. The large white leaf of the 

 Arum Lily is not a corolla, but a large bract enclosing a spike of small 

 flowers, and termed a spathe. 



3. The Stamens. These are situated just inside the corolla, and may 

 vary from one to a hundred or more in one flower. They consist of a 

 filament or stalk, comparable to a leaf stalk, and an anther on the top, 

 corresponding to the blade of the leaf. The filament may be absent but 

 the anther is essential, as it contains the powdery-looking pollen grains 

 (fig. 50) that fertilize the embryo cell. The filaments may be free from 



