40 



7. Other endangered, threatened, rare, car vulnerable species 

 ocxxirring in habitat of this taxcn: 



Idaho - Tauschia tenuissiroa (Leiberg's Lomatium) , a Category 

 2 federal candidate, occurs in bottomland meadows adjacent 

 to the pond containing H. aquatilis . 



Montana - Ihe oily state sensitive aquatic species which is 

 kncwn to occur in the vicinity of H. aquatilis is 

 Potamoqeton obtusifolius (Blunt-leaved Pondweed, G5/S1S2) . 

 This ^jecies occurs at the Swan River 0>dxiw (005) site. 



Washington - C ypripedium caloeolus var. parviflorum (Small 

 Yellcvr Lady's-slipper) , which is considered endangered in 

 the state (Washington Natural Heritage Program 1987) , occurs 

 on the periphery of sons ponds which contain H. aquatilis 

 (J. Gcunon, pers. coitin.). 



Pcspulation biology of taxcn. 



A. General sumnaiy: Populations of H. aquatilis generally consist 

 of a few to several thousand individuals. The ^secies is an 

 annual; population size is known to fluctiiate yeeurly, and is 

 probably mainly associated with vauriation in annual climatic 

 patterns (precipitation and temperature fluctuations) . Recent 

 eviderjoe indicates that the species has no intra- or inter- 

 population genetic variation. Morphological studies and field 

 observations indicate that tf. aquatilis is an obligate self- 

 pollinator. Seeds may be di^aersed between wetland habitats by 

 wildlife use and migration. Evidence for the existence of seed 

 banks has been obtained froro om location in Montana. 



B. Deongraphy. 



1. Rioun populations: A total of 72 recently extant 

 populatiCTTs, from 13 sites, are known: 55 (9 sites) in 

 Montana; 16 (3 sites) in Washington; and 1 in Idaho. A site 

 is considered to be a cluster of adjacent populatic»Ts, each 

 of which is generally no more than 1.6 km from the next 

 nearest population. Populations vary from only a few 

 individueds, up to many thousands of plants. (X/ing to the 

 annual life history, and the presence of seed banks, the 

 total number of kncwn individuals cannot be meaningfully 

 estimated. 



2. GenereLl demographic details: See Table 3, pp. 41-49. 



C. Rienology. 



1. Kittems: Recent <±>servations in Montana revealed that H. 

 aquatilis can germinate in the fall (P. Lesica, pers. 

 comm.) . In Idaho and Montana, the plants are then actively 

 growing beneath the water surface hy early May. Ihe 

 subnergent, cleistogamous flowers begin to form shortly 



