^02 botanical gazette. [ December, 



o 



not touching anthers when sucking. Several species of Syr- 

 phidae eat pollen which is scattered on landing. Only nos. 

 i and 2 are useful visitors. 



Staphylea trifolia L. — Prof. W. J. Beal 10 examined the 

 flowers of this plant and concluded "that the chances are 

 better for cross-fertilization than otherwise." But Mr. Mee- 

 han 11 has interpreted it as adapted to self-fertilization. On 

 the other hand, Dr. Gray 12 held that the* flower is proter- 

 ogynous and cross-fertilized by bees, and my observations 

 led me to the same conclusion, while still unaware of his view. 

 I find from Prof. TVelease's notes that he too regarded the 

 flower as proterogynous. Newly opened flowers show a 

 broad, three-lobed stigma nearly closing the entrance, and 

 the still indehiscent anthers crowded under it. The surface 

 of the stigma is always in advance of the anthers, and can 

 hardly become thoroughly dusted with their pollen, even it 

 it can receive enough for self-fertilization. The most that 

 can be said is that the flower is self-fertilized in absence of 

 insects — a very different thing from saying that it is adapted 

 to self-fertilization. But the small number of fruit com- 

 pared with the number of flowers leads me to doubt whether 

 self-fertilization occurs, even when insects fail. Nectar 

 is secreted by the disk surrounding the base of the ovary. 

 The pendulous flower is about 6 mm. deep and the sepals 

 and petals are erect and closely approximated, so that 

 the flower has much the same form as in the gamo- 

 petalous genus Gaylussacia and has a like effect in exclud- 

 ing insects, although the petals are more yielding- The 

 ovary, filaments and petals within are very hairy, and this 

 also aids in making the honey less accessible to short tongues 

 and in excluding small intruders. The flower thus favors 

 long-tongued bees, although shorter-tongued insects some- 

 times succeed in forcing their way into the flowers far enough 

 to reach the nectar. 



Visitors (observed in five days* between April 23 and 

 May 11): Hvmenoptera — Afi/dce: 1 ) Apis mellifica L. 5 , 



. 9 ; (3) B. vagvns 



Sm. 9 ; (4) B. americanorum F. 9 — all 3 s., ab. Andren- 

 idce: (5-8) Andrena spp. $ 9 , s. and c. p., ab. ; (9) Halic- 



I.; (II) Colletes ma- 



Bomb 



H 



</ 1 talis Say <?, s. Vespidxv : (12) Vesp 



10 Am. Naturalist i. >. 



ll Proc. Acad. Nat. 8ci. Phila., 187fi, lO 



"See Just's Bot. Jahresbericht iv. 9:;.». 



