66 THE ANDROECIUM ^ 



Extrorse by Dehiscence. It does not follow that an anther introrse or 

 extrorse by dehiscence is the same by attachment. 



Confluent Sutures. — In the sagittate-horizontal anther the sutures 

 of the two thecae often become continuous, the Confluent form (Figs. 

 131 and 132). 



Dehiscence by Pores. — Small orifices, called Pores, frequently exist at 

 the apex, as in Ca.s-.sia (Fig. 143), more rarely at the base. The most 

 scrupulous care must be taken to determine the exact direction in which 

 apical pores look. In some cases, as in Solanum, a slight difference 

 will possess specific importance. 



Dehiscence by Valves. — A less common form of discharge is by A^alves 

 (Fig. 138), the common form for the four-locellate anther. Special 

 mechanical contrivances for aiding in the discharge of the pollen are 

 of great interest and will be mentioned under Cross-pollination. 



Cohesion. — Cohesion is responsilile for quite as great and important 

 modifications of the androecium as of the perigone. Here, as there, it 

 may be complete, or, beginning at either apex or base, it may stop at 

 any point. Fig. 84 displays the dilated bases of the filaments of 

 Lysimachia lightly coherent, the detection of the condition calling 

 for the same keen inspection as in the case of the corolla. In Guarea 

 (Fig. 147) the union is seen carried to the anthers, but these left 

 distinct. 



Adelphism. — Coherent filaments are styled Monadelphous when all 

 united (Fig. 147), Diadelphous, when there are two groups, even though 

 one of them contains but one stamen, as in Glycerrhiza (Fig. 146), 

 Triadelphous when three, and so on. It must not be lost sight of that 

 the terms are applied similarly, w^hether the iniion is progressive, the 

 result of cohesion as in this case, or that of incomplete chorisis, as in the 

 Tilia (Pigs. 34 and 37) and Psorospermum (Fig. 38), though its classi- 

 ficatory value is very different in the two cases. 



The Stamen-column. — The term column, previously explained, is 

 changed to Stamen-column for monadelphous stamens. 



The Ssmandrium. — The stamen-column is ordinarily hollow, contain- 

 ing the Gynaecium; but when the flower is staminate, the column is 

 solid, and called a Synandrium. 



When, as seen in Fig. 92, the anthers come together but do not actually 

 cohere, they are called connivent. The cohesion is carried only partly 

 down the filaments in the squash (Fig. 148), and partly upward in the 

 Sidalcea (Fig. 149), but in the Asdepias (Fig. 154) it is complete for 

 the entire organs. 



