50 ELEMENTARY BOTANY. 



long filiform filaments and style, upwardly enrolled in the bud, 

 straighten and project when the corolla opens ; the stamens re- 

 main straight, but the style proceeds to curve downward and 

 backward, as in Fig. 71. The anthers are now discharging 

 pollen ; the stigmas are immature and closed. Fig. 72 represents 

 the flower on the second day, the anthers effete and the fila- 

 ments recurved and rolled up spirally, while the style has 

 taken the position of the filaments, and the two stigmas, now 

 separated and receptive, are in the very position of the an- 

 thers the previous day. The entrance, by which the proboscis 

 of a butterfly may reach the nectar at the bottom, is at the 

 upper side of the orifice. The flower cannot self-pollinate. 

 A good-sized insect flying from blossom to blossom and plant 

 to plant, must transport pollen from the one to the stigma of 

 the other." (Gray.) 



8. The composite flowers, such as the Rudbeckia, Heliopsis, 

 Sunflower, etc., are additional examples of proterandry. The an- 

 thers are united so as to form a tube, the pollen being early dis- 

 charged within. It is pushed out of the tube by the elongating 

 pistil, which is not as yet in a receptive condition. Moreover 

 the pollen cannot be applied to the stigmatic surfaces, for they 

 are on the inner sides of the forks or branches of the tip of 

 the style. They do not spread until the pistil has acquired 

 its full length, and then curving outward, the adjacent pollen 

 is still prevented from access to the stigma. The conspicuous 

 ray-flowers doubtless serve for the attraction of the many vis- 

 iting insects, and they, by their more or less hairy bodies, con- 

 vey the adhering pollen from some of the flowers to the ex- 

 posed stigmas of others ; and thus cross-pollination is eSected. 

 Other proterandrous flowers are the Gentians, Epilobium, 

 Campanula, Parnassia, Lobelia, etc. The stamens in Lobelia 

 are like those in the Sunflower family, that is, united by their 

 anthers and forming a tube around the upper portion of the 

 style. The pollen is discharged while the style is yet so short 

 as to be concealed deep down in the tube (Fig. 73). As the 

 stigma approaches maturity, the style elongates and pushes 

 the pollen out before it ; the mouth of the tube is so situated 



