IRIDACE^ 



173 



two are alike, except that the inner whorl of stamens is missing 

 from the latter. If we now add these three missing stamens to 

 the Iris-diagram, 

 all the successive 

 whorls of the 

 flower alternate in 

 the usual manner. 

 We therefore sup- 

 pose that in the 

 Yellow Flag (and 

 other Iridaceae) 

 the inner whorl of 

 stamens is sup- 

 pressed; and, con- 

 sequently, in a 

 floral diagram (fig. 

 219) we put dots 

 to represent the 

 missing whorl, and 

 write down the 

 androecium as 

 3 -t- o (not as 

 three). Fruit (fig. 

 122) a capsule 

 splitting along the 

 dorsal sutures. 

 The numerous flat 

 endospermic seeds 

 are dispersed by 

 the wind. 



Pollination. — 

 [In order to under- 

 stand the method 

 of pollination, a careful examination of the flowers themselves 

 is absolutely essential.] The honey is excreted by the inner 

 face of the base of the perianth-tube, and collects round 

 the base of the style. If an insect is to obtain honey, it 

 must therefore be able, in some way, to reach down nearly 

 to the bottom of the long perianth-tube. Consequently, 

 only insects with long tongues can sip the honey. The Yellow 

 Flag has two varieties of flowers. The one variety is especially 



Fig. 217. — Vertical section of flower of Yellow Flag. 

 Fig. 2r8. — Stamen with the overhanging . arm of 

 style and stigma (y^) of ditto. 



