IMPERFECT FLOWERS. 



61 



ber, two long and two short. Tetradyn! amous stamens are 

 six in number, four long and two short (as in the Mustard 

 tribe, Fig. 182). Again, hypogynoics stamens may be seen 

 in the Crowfoot tribe and in Fig. 132 ; and perigynous sta- 

 mens in the Rose tribe and Fig. 133. "What is the differ- 

 ence? You need not be told the meaning of these words 

 (§§ 83, 84). 



109. Some plants have their essential organs separated, so 

 that the stamens are all found in one sort of flowers, the 

 sterile^ and the pistils are all in another sort, i\\Q fertile. So 



189 ISS 18T 1S6 



Fig. 186. Flower of Lizard-tail (Saururus) ; it is perfect, but naked, i. c, with nc 

 floral envelopes ; stamens seven, pistils three. 

 Fig. 187, Flower of Ash (Fraxinus), — naked, with two stamens and one pistil. 

 Fig. IBS. Stiiminate flower of Willow, — made up of two stamens and a bract. 

 Fig. 189. Pistillate flower of the same, — merely one pistil and a bract. 



it is in the Begonias (Fig. 185), and in the Willows (Figs. 188, 

 189). All such flowers are called imperfect, and only the fer- 

 tile bear fruit. 



110. A perfect flower is one that has both stamens and 



108. In what two cases do we mark the length of stamens ? Define " sta- 

 jiens didynamous ;" " stamens tetradynamous ;" " stamens hypogynous ;'' 

 " stamens perigynous." 



109. What do you understand by " sterile flowers ?" by " fertile flowers T 



110. What is a porf\.^ct flower? complete? imperfect? 



