ALGAL FLORA OF THE MISSOURI BOTANICAL GARDEN. 33 



ter by mulching, freeze early and remain frozen late. The 

 Nelumbium spcciosum which grows in them is a tropical 

 plant native to Eur- Asia. 



There are two well marked seasonal groups here. None of 

 the fall (Oct.-Dec. incl.) were observed in the spring (Mar.- 

 May incl.) and vice versa with the exception of the diatoms 

 which have been found in all the stations in greater or les$ 

 abundance. The four species which were particularly char- 

 acteristic in the fall are Anabaena Flos-aquae, Nostoc, Spiro- 

 gyra setiformis and Pithophora Mooreana (see syst. list) a 

 new species. These genera by history are well adapted to 

 tropical life. Oedogonium though represented in some de- 

 gree in most of the stations was rare here. The spring group 

 is free swimming, free floating including Volvocaceae, Flag- 

 ellatae, Scenedesmaceae, — C hlamy domonas gloeocystiformis, 

 Euglena proximo, and Gonium pectorale being very abund- 

 ant for a short time. This is the only location in the garden 

 in which Spirogyra setiformis and Pithophora Mooreana were 

 found. This with the fact that the Nelumbium speciosum 

 is a tropical plant is of interest here. The genera Scenedes- 

 mus and Phacus are the best represented of the spring group 

 with regard to species though the relative representation of 



each species is not great. 



Nymphaea pool is a large cement basin 15x30 ft., situated 

 between the two Nelumbium pools. The description of the 

 Nelumbium pools applies to this one except that the water 

 is from 6 in. to 1 ft. in depth. Here are found Nymphaea 

 Marliacea var. chromatella, N. Marliacea var. carnea, N. Glad- 

 ♦ stoniana and N. Robinsoniana. 



The algae in this pond were in the fall casually observed, 

 not studied by weekly microscopic examinations, as those 

 from the other locations. Tt was noted, however, that Spiro- 

 yyra setiformis and Pithophora Mooreana were not present in 

 the Nymphaea pool though the Nelumbium basins were but 4 

 ft. away. The most conspicuous thing here was a very abund- 

 ant growth of Spirogyra dubia which was first attached to 

 bricks in the pool becoming free as it rapidly developed. The 



filaments simultaneously went into conjugating state April 



3 



