516 



Saxifragaceae 



Tiarella 



50 



Map 1069 



Heuchera americana var, interior 

 Rosendahl , Butters & Lakela 



:ra / 50 



Map 1070 



Heuchera americana var. hirsuticaulij 

 IWheelock) Rosendahl , Butters, 4 Lakela 



absent or rare. No doubt it is absent from the southern counties for 

 reasons other than the lack of habitat. 



Maine, Ont. to Minn., southw. to Va. and Mo. 



3193. TIARELLA L. 



[Lakela. A monograph of the genus Tiarella L. in North America. 

 Amer. Jour. Bot. 24: 344-351. 1937.] 

 (See excluded species no. 283, p. 1055.) 



3195. HEUCHERA L. Alumroot 



[Rosendahl, Butters, and Lakela. A monograph on the genus Heuchera. 

 Minnesota Studies in Plant Science 2 : 1-180. 1936.] 



All of my specimens have been named by the authors of this monograph. 



The following key has been adapted from the monograph cited above. 



Petioles of leaves glabrous, merely puberulent, or sparingly hirsute above 



1. H. americana var. brevipetala. 



Petioles more or less densely hirsute. 



Outside of calyx glandular-puberulent, without any long white hairs. 



Flowers in anthesis mostly 3-4.5 mm long; hypanthium regular or somewhat 

 oblique. 

 Flowers in anthesis 3-3.5 mm long; hypanthium regular or nearly so; petals 

 1-1.5 mm long, narrowly elliptic to short-spatulate, with a short, relatively 



broad claw la. H. americana var. interior. 



Flowers in anthesis mostly 4-4.5 mm long; hypanthium somewhat oblique; petals 



2-3 mm long, oblanceolate with narrow claws and rhombic tips 



lb. H. americana var. hirsuticaulis. 



Flowers in anthesis mostly 5-10 mm long; hypanthium strongly to moderately 

 oblique. 



Flowers mostly 5-7 mm long; hypanthium moderately oblique 



2. H. Richardsonii var. affinis. 



Flowers mostly 6-10 mm long; hypanthium strongly oblique 



2a. H. Richardsonii var. Grayana. 



