A perfect flower is formed of a double perianfch, a circle 

 of stamens, and a central pistil. 



The outer circle of the perianth is the calyx; it is com- 

 monly green like the leaves, and made up of three, four, 

 or five parts, each of which is called a sepal. These sepals 

 may be all free from one another or variously united. 

 When the calyx is green and of coarse structure, its duty 

 is evidently that of an outer covering to the bud, while 

 the more delicate organs are being formed within. Some- 

 times the calyx is not so structured, but may be coloured 

 and delicate when it assumes the duty of the next circle, 

 and may be mistaken for it. 



The inner circle of the perianth is the corolla. It is 

 usually coloured and delicate, and made up of three, four, 

 or five parts, called petals, which may be all free or 

 variously united. They may be all equal and similarly 

 constructed, or unequal. When the petals are not all 

 similar the coralla is said to be irregular. As a rule the 

 petals are so inserted that they alternate with the sepals. 

 In most flowers there is a clear distinction between the 

 calyx and corolla, but not in all. Sometimes the passage 

 from one to the other is gradual, and not clearly marked. 

 When the corolla is delicate and brightly coloured its 

 work is evidently to attract attention. It is of first import- 

 ance to many plants' that insects or, in some, birds shall 

 be induced to visit their flowers. 



Within the perianth is a circle of stamens. A typical 

 stamen may be likened to a small pin. The shaft is slen- 

 der and delicate, and is called the filament; the head is 

 round or long, yellow or dark, and is called the anther. 

 A stamen does not look like a leaf, but it is one. Stamens 

 of some flowers are very leaf -like, and in deformed flowers 

 this condition is often reverted to. 



The anther, though placed on the staminal leaf, is a 

 separate organ developed there for convenience. It is the 

 direct descendant of the small spore-bearing sacks of 

 lower plants. The anther is made up of four sacks, which 

 may all remain till maturity or they may coalesce in pairs, 

 so that when mature the anther consists of two sacks, or 

 further, all four may blend into one. The anther when 

 mature consists of one or more sacks containing coloured 

 dust. Each particle of this dust is a spore, but in a 

 flower we call it a pollen grain. A pollen grain is a beauti- 

 ful object under the microscope. It has two coats: the 

 outer one is variously marked, with ridges or spines 

 according to the species; the inner one is very thin, and 



