STAMENS AND THEIR WORK. 



37 



families some or all of the small tubular corollas appear as if 

 split part way down on one side and then flattened. Such a corolla 

 is said to be ligulate or strap-shaped, the split portion being called 

 a ray. 



The corolla is often wrongly called the "flower." This is be- 

 cause it is usually the showy or attractive part to humans. How- 

 ever, it was not made handsome to attract man but insects, so as 

 to bring about a better pollination or cross fertilization of the es- 

 sential organs. It also serves to sonic extent to protect those or- 

 gans in the bud. In endogens the sepals and petals are, when pres- 

 ent, 3 each in number and often colored alike to form what is 

 known as the perianth. 



The duty of the stamens, or outer set of essential organs of a 



Fig. 11. Ilhstrating stamens and pollen grains: a, stamen of henbane, /, filament, p, anther; b, flower of 

 mallow with calyx and corolla cut away, showing the monodelphous stamens united in a column around the styles; 

 c, stamens of pea in two groups (diadelphous) 9 and 1; d, stamen with versatile anther as in grasses and evening- 

 primrose; e, stamen of horss nettle, the pollen escaping by terminal pores; /, stamens of a Composite showing 

 the anthers united in a tube: g, s^me with tube split and spread out; h, a 3-lobed pollen grain of evening-prim- 

 rose; i, a pair of pollen masses of a milkweed flower attached by stalks to a gland. (After Gray.) 



flower when both are present, is to produce pollen grains or spores. 

 These grains are the male or fertilizing agents of the flower. A 

 stamen usually consists of a stalk or filament and an anther, the 

 latter being made up of 2 sacs or cells in which the pollen is 

 formed and held until it is ready for use. When the pollen is ripe 

 the sacs open by slits or pores and the pollen is scattered by the 

 wind, insects or other agencies. The stamens vary greatly in num- 

 ber, length of filament, form of anther, degree of union one with 

 another, and mode of insertion or connection with other parts of 

 the flower. All of the filaments may be joined together as is the 

 case in the velvet leaf and other weeds of the mallow family, or 

 they may be united in sets as in the St. Johnswort and many plants 

 of the pea family. In the weeds of the Composite family the an- 

 thers are united to form a ring about the style. 



