488 



CLASSIFICATION OF ANGIOSPERMS. 



these different species, a relationship which includes more than the 



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



then, this is a relationship 



with broader limits, and 



of a higher grade, than 



that of the individuals of 



a species. The grade next 



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 of 

 six 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-like 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 employed 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 fig. 496, 

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

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

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

 near the base. Stamens are 6. The ovary is obovate, tapering 

 at the base, 3-valved, seeds rather numerous, and the style is 

 elongated. The flower stem, or scape, arises from a scaly bulb 

 deep in the soil, and is sheathed by two elliptical-lanceolate, 



Fig. 495. 

 Trillium erec- 

 tum (purple 

 form), two 

 plants from one 

 rootstock. 



