440 Key to the System of 



FLUVI ALES. 

 TRIGZ.OCKZN. 



1875. Annual 1876 



Perennial ... 1877 



1876. Flowers minute, with very slender pistils. 



Very dwarf and thin ; leaves almost setular-linear ; lower 

 flowers in the spike often with three sepals and one 

 stamen only ; terminal flower with six stamens ; fruitlets 

 longitudinally adnate, very narrow, three fertile and 

 bidenticulate at the base. T. centrocarpa. 



Flowers rather small, with comparatively thick pistils. 



Rather dwarf ; leaves filiform ; lower flowers in the spike 

 mostly with one stamen only ; terminal flower with three 

 stamens ; fruitlets six, longitudinally adnate, alternately 

 sterile and fertile, the latter truncate and terminated by 

 the spreading style. T. mucronata. 



1877. Somewhat tall, quite slender. 



Root producing offshoots ; leaves filiform-linear ; flowers 

 generally numerous, with three stamens ; fruitlets six, 

 three sterile and three fertile, placed alternately, the 

 latter oblique-orbicular, dorsally streaked. T. striata. 



Usually tall and robust. 



Root producing tubers ; leaves very long and propor- 

 tionately broad, somewhat succulent, sometimes floating ; 

 spike quite long; flowers numerous, comparatively large ; 

 fruitlets usually six, all fertile, from almost orbicular to 

 occasionally obliquely lanceolar-ellipsoid, adnate only 

 towards or at the base, often somewhat twisted. 



T. procera. 

 POTAlttOCETON. 



1878. Leaves of two very distinct forms ... ... 1879 



Leaves all alike or similar in form ... ... ... 1880 



1879. Floating leaves firm. 



Leaves all scattered and stalked ; floating leaves from 

 cordate- to elliptic-ovate; submerged leaves membranous, 

 narrow-lanceolar, quickly decaying ; stipules long-pointed ; 

 stalks of the spikes rather thick ; fruitlets comparatively 

 large, when fresh at the outer margin blunt, their style 

 very short. P. natans. 



