92 Key to the System of 



Pistillate flowers singly sessile ... ... 452 



452. Leaves opposite. 



Oceanic plants ; leaves small ; flowers between distinct 

 bracteoles axillary ; the staminate flowers distinct from 

 the pistillate ; calyx-tube of the latter very much 

 narrowed towards the summit; petals absent; stamens 

 three ; stigmas three ; fruit small ; seeds many. 



Halophila. 1819 



Leaves mostly in whorls. 



Freshwater-plant ; leaves short ; flowers between connate 

 bracteoles axillary ; the staminate flowers distinct from 

 the pistillate ; calyx-tube of the latter very narrow 

 towards the summit ; petals present ; stamens three to 

 nine ; stigmas usually three to six ; fruit small ; seeds 

 few or many. (Hydrilla.) Elodea. 1820 



IRXDEAE. 



453. Lobes of calyx petaloid, usually about as large as the 



petals. 



Root fibrous, sometimes creeping ; leaves often narrow ; 

 clusters of flowers more than one ; calyx-lobes blue, 

 white or yellowish ; petals usually similar to the calyx- 

 lobes ; stamens three ; style shorter than the stamens ; 

 stigmas three, narrow ; fruit often exserted beyond the 

 bracts. Sisyrinchium. 1821 



Lobes of calyx petaloid, considerably or very much 

 larger than the petals ... 454 



454. Stamens three. 



Root fibrous ; leaves always narrow ; cluster of flowers 

 singly terminal ; general outer bract large, clasping ; 

 calyx-lobes blue, rarely yellow ; petals minute ; style 

 longer than the stamens ; stigmas three, broad ; fruits 

 enclosed. Figure 114. Fatersouia. 1823 



Stamens two. 



Root fibrous ; leaves sometimes rather broad ; cluster of 

 flowers often only one ; general outer bract large, clasp- 

 ing ; one of the calyx-lobes larger than the two other ; 

 petals somewhat shorter than the calyx-lobes and as well 

 as these white or tinged with blue and yellow ; style 

 longer than the stamens ; stigmas three, broad ; fruit 

 exserted ; seeds flat. Diplarrhena. 1826 



