456 TRANS. ST. LOUIS ACAD. SCIENCE. 



bylidse, Conopidre. and lepidoptera, than on any other umbellifer, and 

 more Apidae than any other except Zizia. 



E. campestre, according to Schulz,* has the first umbels with only her- 

 maphrodite flowers, and the last with only male ones. Miiller's list of 24 

 species whollj' fails to indicate the character of visitors favored by the 

 floral stiucture. 



Slum cicu/cr/bli'um, Gmelin. — Five umbels of each order bore an aver- 

 age of flowers and umbellets as follows : 



ist order — o male and 415 hermaphrodite flowers in 13 umbellets. 

 2d order— o ' •' 689 " ' ' 23 " 



3d order — o " " 521 " " " 21 '' 



4th order— 279 '• " 58 " " "16 " 



Umbels of the 4th order are usually entirely male. In less vigorous 



plants, umbels of the 4th order are wanting, and those of the 3d are en- 

 tirely of male flowers. The hermaphrodite flowers are proterandrous. 



This plant closely resembles Cicuta, but the list is much smaller, since 

 they do not grow under conditions as favorable for observation. 



The list shows more species of Bombylidse than in Eryngium, but the 

 five species were represented by only one individual of each. 



Tiedmannta rigida^ C. & R. — Five umbels of each order bore an av- 

 erage of flowers and umbellets as follows : 



ist order — 27 male and 594 hermaphrodite flowers in 23 umbellets. 

 2d order — 385 " " 70 " " " 19 " 



In well developed plants the primary umbels are entirely of herma- 

 phrodite flowers, and umbels of the 2d order are entirely male. Umbels 

 of the 3d order are rare and contain only male flowers. They represent 

 umbellets of secondary umbels. Twenty plants bore 20 umbels of ist or- 

 der, 50 of the 2d, and 3 of the 3d. The hermaphrodite flowers are pro- 

 terandrous. 



In regard to visitors, Tiedmannia agrees essentially with Cicuta and 

 Sium, but there seems to be a tendency for hymenoptera to fall off, proba- 

 bly on account of the late blooming. Thus Sium shows 25 more hymen- 

 optera, but only 6 more flies. Cicuta shows 63 more hymenoptera and 

 only 20 more diptera. 



Hydrocotyle umbellata, L. — I found only hermaphrodite flowers, which 

 are proterandrous. While the anthers are discharging pollen the styles 

 are bent over upon each other. 



The plant was observed at Orlando, Florida, in March, and, although 

 it blooms earlier than Erigenia in Illinois, it shows insects which do not 

 occur when Erigenia is in bloom. It agrees with early species having 

 fully exposed nectar in showing a preponderance of diptera. 



