104 Rhodora [May 



ment is correct it easily accounts for the widespread distribution of 

 the species in this vicinity. — Luman Andrews, Southington, Con- 



necticut. 



Biological Relation ok Polygonum Hartwrightii to P. am- 

 phtbium. —Polygonum Hartwrightii, Gray, and/*, amphibium, L., ordi- 

 narily seem quite distinct. P. amphibium is generally found in water 

 and has thick shining leaves on long petioles, mostly clustered at the 

 end of the long Moating steins. P. Hartwrightii is usually found on 

 muddy borders of ponds or along ditches in wet meadows, has longer 

 and narrower leaves that are nearly sessile and more or less hairy, 

 the stems are erect, very leafy, and the sheaths have a peculiar foli- 

 aceous spreading border. It is to be noted however that Dr. Gray 

 in describing P. Hartwrightii, states that it is very closely related to 

 P. amphibium, the flowers and fruit being the same, the only differ- 

 ence being in the habit and foliage. P. Hartwrightii is notoriously 

 sterile, it being a rare thing to find it in fruit in this region. 



Attention was called to these plants in consequence of the finding of 

 what appeared to be P. Hartwrightii where before only P. amphibium 

 had been seen. The writer had supposed the two forms to be distinct 

 and every endeavor was made to prove that to be the case, but without 

 avail. Polygonum amphibium is common in Shuttle Meadow Lake, 

 in Southington. This lake furnishes the water supply for the city 

 of New Britain, and most of these observations were made at this 

 station, though the same facts were noted at another place. 



During the long dry summer of 1900, the water in the lake was 

 drawn down to much below its ordinary level, and its sloping banks 

 gave an unusual opportunity to study the plants under varying condi- 

 tions. The facts as found after several visits and much tracing out of 

 stems and root systems were as follows : 



As the water receded the floating stems of P. amphibium were 

 left stranded on the banks. They would retain life for a time, 

 often taking root at the tip and sometimes at the joints, but generally 

 would at last die and wither away from exposure to the dry air. Then 

 from the same root or from the lower joints of the old stems would 

 spring new erect stems having the foliage of P. Hartwrightii. Differ- 

 ent forms of leaf would occur showing all variations of intergrading 

 forms. 



