488 



CLASSIFICATION OF ANGIOSPERMS. 



these different species, a relationship which inchides more than the 



individuals of one kind. It includes several kinds. Obviously, 



then, this is a relationship 



with broader hmits, and 



of a higher grade, than 



that of the individuals of 



a species. The grade ne.xt 



higher than species we 



call genus. Trillium, 



then, is a genus. Briefly 



the characters of the genus 



trillium are as follows: 



931. Genus trillium. — Perianth ot 

 si-x parts: sepals 3, herbaceous, per- 

 sistent; petals colored. Stamens 6 (in 

 two whorls), anthers opening inward. 

 Ovary 3-loculed, 3-6-angled; stig 

 mas 3, slender, spreading. 

 Herbs with a stout per- 

 ennial rootstock, with 

 fleshy, scale-hke leaves, 

 from which the low annual 

 shoot arises, bearing a terminal flower and 3 large netted-veined 

 leaves in a whorl. 



Note. — In speaking of the genus the present usage is to say 

 trillium, but two words are usually emploved in speaking of the 

 species, as Trillium grandiflorum, T. erectum, etc. 



932. Genus erythronium. — The yellow adder-tongue, or 

 dogtooth violet (Erythronium americanum), shown in hg. 4QO, 

 is cjuite different from any species of trillium. It differs more 

 from any of the species of trillium than thev do from each 

 other. The perianth is of six parts, light yellow, often spotted 

 near the base. Stamens are 6. The ovarv is o1>o\'a(e, tapering 

 at the base, 3-valve(l, seeds rather numerous, and the style is 

 elongated. The flower stern, or scape, arises from a scab' liull) 

 deep ii"i the soil, and is sheathecl li\' two elliptical-lanceolate. 



Fir. 495. 

 Trillium erec- 

 tum (purple 

 form), t \v o 

 plants frrim one 

 rootstock. 



