24 



TECHNICAL DESCRIPTION: Plants matted or with some branches # 

 ascending and 2-4 cm (.8-1.6 in) long; leaves spathulate to 

 obovate, less than 10 mm. long, the tips rounded and not at 

 all emarginate; sepals and petals 3, seeds spomewhat curved, 

 the pits mostly 18-27 in each of about 10 longitudinal rows 

 (Hitchcock et al. 1984). 



LOCAL FIELD CHARACTERS: American waterwort is not 

 recognized in the most recent state flora (Dorn 1984). It 

 is similar to and difficult to distinguish from Three-stamen 

 waterwort (E. triandra ) , which has linear to narrowly 

 oblanceolate leaves which are typically notched, compared to 

 the obovate rounded leaves of American waterwort. Its seeds 

 also have more pits per row (18-27 vs. 10-15). 



GEOGRAPHICAL DISTRIBUTION 



1. RANGE: American waterwort is a North American species with 

 its center of distribution on the Atlantic coast. In 

 Montana, it is known from Garfield, and Lewis and Clark 

 counties east of the Divide, and Lake and Ravalli counties 

 west of the Divide. 



2. CURRENT SITES: All four of the Montana collections records 

 mentioned above are relatively recent, and presumed extant. 



3. HISTORICAL SITES: None. 



4. UNVERIFIED/UNDOCUMENTED REPORTS: None. 



5. AREAS SURVEYED BUT SPECIES NOT LOCATED: BIJ^ lands around 

 the Squaw Creek drainage where it was previously collected 

 were searched for this species, but suitable habitat was not 

 found. The early-season timing of the survey or the extent 

 of the survey may have been inadequate for the task. 



HABITAT 



ASSOCIATED VEGETATION: American waterwort occupies the 

 mudflat drawdown zone of ephemeral pools, where it is found 

 in the absence of other vegetation or with scattered 

 emergents. Only the Ravalli County occurrence includes 

 information on associated species: Potamogeton 

 richardsonii , Limsella aquatica and Elec haris acicularis . 

 Note: This species was originally collected in Garfield 

 County on the same day in the same general vicinity as the 

 Round-leaved water-hyssop, but it is not known whether they 

 occupy the same precise location and habitat. 



