CLASS I PICA TION. 



649 



from it. So are a number of others. But the purple trillium 

 is a species. It is made up of individuals variable, yet very like 

 one another, more so than 

 any one of them is like 

 the white wake-robin. 



1134. Genus. Yet if 

 we study all parts of the 

 plant, the perennial root- 

 stock, the annual shoot, 

 and the parts of the flower, 

 we find a great resem- 

 blance. In this respect we find that 

 there are several species which possess 

 the same general characters. In other 

 words, there is a relationship between 

 these different species, a relationship 

 which includes more than the indi- 

 viduals 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: 



1135. Genus trillium. Perianth of six parts: sepals 3, her- 

 baceous, persistent; 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 perennial root- 

 stock, 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. 



1136. Genus erythronium. The yellow adder-tongue, or 



Fig. 537- 

 Trillium erec- 

 tum (purple 

 form), two 

 plants from one 

 rootstock. 



