FLOWERS 



111 



groups (Figs. Ill and 121). In such cases the stamens are said 

 to be monadelphous, diadelphous, triadelphous, polyadelphous 

 (in one, two, three, many brotherhoods). The function of the 

 stamen is to produce pollen, a powdery or pasty substance com- 

 posed of separate grains (Figs. 105 and 106), which is formed 

 within four cavities in the anther (Fig. 99). The two cavities 

 on each side generally join to form a single larger pollen sac 

 as the anther matures. Pollen is discharged from the mature 

 anther in various ways, as shown in Fig. 100. The special 

 significance of some of these modes of discharge is explained 

 in Chapter VIII. 



101. The carpel. The simplest form of the organ which 

 bears ovules or rudimentary seeds is called a carpel (from a 

 Greek word meaning "fruit"). The most elementary kind 

 of carpel is found in 



the lowest seed plants, 

 and often consists, as 

 in the pines and other 

 cone-bearing trees, of 

 a single scale, with a 

 naked ovule borne at 

 its base (Fig. 252). 

 In the higher seed 

 plants the carpel con- 

 tains an ovule-bearing 

 cavity (Figs. 14 and 

 101), in which the 

 ovules are completely 

 inclosed while they 

 are maturing. 



102. The pistil. The entire carpellary portion of the flower 

 of the higher seed plants is called a pistil (Latin for pestle). 1 

 In flowers which have but one carpel, pistil and carpel mean 



1 It would be better to call it, as some botanists do, gynceceum, but the 

 word pistil is so much in use in descriptive botany that it seems likely to be 

 retained for a good while, 



FIG. 100. Various types of anther 



A, iris, discharging pollen by a longitudinal slit; 



B, barberry, discharging pollen by uplifted valves ; 



C, nightshade; D, bilberry, discharging pollen 

 through holes or pores at the top of the anther. 



A, B, C, after Baillon ; Z), after Kerner 



