ROBERTSOX FLOWERS & INSECTS, ASCL. TO SCROPII. 5S9 



The stigma stands among the anthers, and sometimes appeal's 

 receptive before they discharge. When the lower lip is forced 

 down, the stigma may touch the bee in advance of the anthers ; 

 but, in the absence of insects, I find nothing to prevent the stig- 

 ma from receiving pollen from the surrounding stamens. In 

 Miiller's " Fertilization of Flowers," 436, it is stated that, in the 

 absence of insects, flowers of this plant and of C bicolor fertilize; 

 themselves, and are fertile to their own pollen. 



I regard the flower as specially adapted to early-flying bees 

 with abdominal collecting-brushes — i.e. species of Osmia — and 

 these bees, although not the exclusive visitors, are far more 

 abundant and more important than all of the other visitors to- 

 gether. As an illustration of the extent to which the economy of 

 these bees is associated with the flower, may be mentioned the 

 fact that the females of the four species found on the flowers all 

 collected pollen, and that they were the only native bees collect- 

 ing pollen, except a single individual of Halictus Lerouxii. 

 Bombylius, Empis, and butterflies, are mere intruders, since 

 they can reach the nectar without depressing the lower lip, and 

 so without touching anthers or stigma. 



In the order to which it belongs, Collinsia is remarkable from 

 the fact that it dusts its visitors on the ventral surface instead of 

 on the back. As in the cases of Verbascum and Scrophtdaria^* 

 I suppose that the flower originally applied its pollen to the backs 

 of the bees ; then that the flower changed so as to expose its 

 stamens in such a way that insects could alight upon them ; then 

 the stamens turned to the lower side, and the flower became fur- 

 ther modified to suit bees with abdominal collecting-brushes. 



In 1S90 I found the flowers in bloom from April 31 to June i. 

 On four days, between April 21 and May S, I captured the fol- 

 lowing visitors : 



Hymenoplera. — Apid<M, (i) Apis mellifica L. ^,s. &c.p.; (2) Bom- 

 bus americanorum F. 9j s.; (3) B. ridingsii Cr. 9? s.; (4) B. separa- 

 tus Cr. ?, s. ; (5) B. scutellaris Cr. 9, s.; (6) B. pennsjlvanicus DeG. 

 9, s.; (7) Anthophora ursina Cr. ^, s. ; (S) Sjnhalonia speciosa Cr. 

 (^, s. ; (9) S. honesta Cr. J^, s. ; (10) Ceratina dupla Say (^^, s., freq. ; 

 (11) Osmia atriventris Cr. J*9' s. & c.p., ab.; (12) O. albiventris Cr. 



* Bot. Gazette, xiii. 225. 



