DICOTYLEDONS 211 



the flower in longitudinal section, showing the position of the 

 pistil and stamens. Then remove all the petals, and spread 

 in their natural order on the table before you, and sketch 

 as they lie (Fig. 409). Label the large, round upper one, 

 vexillum, the smaller pair on each side, wings, and the two 

 more or less coherent ones in which the pistil and stamens 

 are contained, keel. Corollas of this kind are named papili- 

 onaceous, from the Latin word papilio, a butterfly, on ac- 

 count of their general resemblance to that insect ; while the 

 old names are somewhat incongruous, they are descriptive, 

 and answer their purpose sufficiently well to be retained. 



299. Dissection (continued}. Count the stamens, and 

 notice how they are united into two sets of nine and one. 

 Stamens united in this way, no matter what the number in 

 each set, are said to be diadelpJious, that is, in two brother- 

 hoods. Notice the position of the lone brother, whether 

 below the pistil next to the keel or above, facing the 

 vexillum. Would the projection of the pistil when the 

 wings are depressed be facilitated to the same extent if 

 the opening in the stamen tube were on the other side, or 

 if the filaments were monadelphous all united into one 

 set ? Flatten out the stamen tube, or sheath formed by 

 the united filaments, and sketch it. 



Remove all the parts from around the pistil, and sketch 

 it as it stands upon the receptacle. Look through your 

 lens for the stigmatic surface (Sec. 293). See if there are 

 any hairs upon the style, and if so, whether they are on 

 the front, the back, or all around. Can you think of a 

 use for these hairs ? 



300. Dissection (continued}. Notice how the long, nar- 

 row ovary is attached to the receptacle; is it sessile, or 

 raised on a short footstalk ? If the latter, label the foot- 

 stalk stipcl. Select a well-developed pistil from one of the 

 lower flowers, open the ovary parallel with its flattened 

 sides and sketch the two halves as they appear under the 

 lens. Notice to which side the ovules are attached, the 

 upper (toward the vexillum) or the lower, and label i> 



