THE MORPHOLOGY OF WEEDS 



129 



one set, they are monadelphous ; when in two sets, dia- 

 delphous, and so on. When there is one stamen, the flow- 

 er is monandrous ; two, diandrous ; and so on. The parts 

 of the stamen are the filament, anther, and pollen. When 

 the pollen is united in a mass it is spoken of as a pollinium, 



Fig. 73. Regular flower of rose: 5 green reflexed sepals, 5 petals 

 (Ada Hayden.) 



as in the milkweed. When the filament is attached in the 

 middle it is versatile, when attached by its base it is 

 innate, when attached by one face it is adnate. When the 

 anther opens outwardly it is extrorse; inwardly, in- 

 trorse. 



Ovules, Fruits and Seeds. There are two classes of 

 flowering plants classified with reference to the manner 

 in which the ovules occur. In 

 the Gymnosperms, the ovules 

 and seeds are borne on the face 

 of a scale, as in the pine, spruce 

 and cedar. In the Angios- 

 perms, the ovules and seeds are 

 contained in a closed ovary, as 

 in the bean, corn, maple, etc. 

 The carpel is a modified leaf 

 forming- the ovary or a part of 

 the compound ovary. The Fig. 74. Pollen grains of 

 dorsal suture corresponds to the yarious types. (Redrawn 



. , ., ,, , from Hamilton-Gibson. C. M. 



midrib of the leaf, the ventral King.) 



