218 - Multicellular Plants 



Stamens 



Fig. 12-15. 

 white water 

 eral Biology, 

 Co.) 



Transition from petals to stamens in the 

 lily. (Redrawn after Asa Gray. From Gen- 

 by Mavor. By permission of The Macmillan 



In form, the anthers are so highly modified 

 as to be quite unrecognizable as leaves (Fig. 

 12-15). This is also true of the macrosporo- 

 phylls (commonly called the carpels) which 

 make up the innermost whorl, at the very 

 center of the flower. In most flowers the car- 

 pels are united, partially or completely, to 

 form a single compound organ called the 

 pistil (Fig. 12-14). Typically the pistil con- 

 sists of an enlarged hollow basal part, the 

 ovule chamber, surmounted by a slender cyl- 

 inder, the style, which terminates in a moist 



Fig. 12-16. The tulip is one of the Monocotyledoneae. 

 The flower displays 3 sepals, 3 petals, 6 stamens, and 

 a compound pistil with a 3-branched stigma. (From 

 Co//ege Botany, by Fuller and Tippo. Holt, Rinehart 

 and Winston, Inc.) 



sporangia) in which the pollen grains 1 (mi- 

 crospores) are produced in great numbers. 



1 The terms "pollen grain" and "microspore" are 

 almost, but not quite, synonymous, since the micro- 

 spore nucleus usually divides once before the pollen 

 is shed. 



B 



Fig. 12-17. Flowers of Amaryllis, one of the Mono- 

 cotyledoneae. A, close-up of the stamens and stigmas; 

 B, the whole flower. This flower has 3 sepals, 3 petals, 

 6 stamens, and 3 forked stigmas. (From Co//ege Botany, 

 by Fuller and Tippo. Holt, Rinehart and Winston, Inc.) 



