166 



Trans. Acad. Sci. of St. Louis. 



8. ulmifolia and chamaedri folia the scent is aminoid 

 (Kerner). 



In the case of S. opulifolia, Ludwig (13, 14) observes that 

 the reddish color of the ovary in old flowers, which becomes 

 more evident in the fruit, serves to increase the conspicuous- 

 ness of the plants and to draw unbidden guests away from the 

 younger flowers. He saw the flowers visited by bees and 

 Syrphidae. 



The principal visitors of Spiraea are flies, especially Syr- 

 phidae, beetles, and bees, especially Andrenidae. Other flies 

 and the lower Hymenoptera are less abundant. The follow- 

 ing table gives the results of observations in this line: — 



fsalicifolia| m . xed 

 Spiraea^ ulmifolia > ^ 

 [sorbifolia J 

 ulmaria 



(t 



K 



(( 



(( 



(( 



fllipendula 



digitata 



aruncus 



Low Germany. 



Miiller (i, 8) 



Flanders MacLeod (24) 



Scotland Willis (26)... 



Pyrenees j MacLeod (20) 



Netherlands .. 

 North Frisian 



Islands 



Alps. 



Low Germany. 

 Berlin Garden. 



Alps 



Low Germany. 

 Illinois 



Heinsius (21) 



Knuth (25)... 



Miiller (10).. 



" (4,8) 



Loew (12).... 



Miiller 



(10).. 

 (4,8) 



110 



35 



19 



11 



3 



2 



1 



10 



2 



5 



1 



15 



51 



Spiraea aruncus L. — Aruncus aruncus (L.) Karst. — I 

 find nectar to be secreted by a perigynous disc, as observed by 

 Delpino (5). On the other hand Miiller (4, 10) states that 

 the flowers are devoid of nectar, but he does not explain how 

 the pistillate flowers, which of course bear no pollen, are to 

 be visited. 



According to Gray's Manual and Chapman's Flora, 

 the flowers are dioecious, and this is the only condition in 

 which I have found them. The staminate flowers have twenty 



