232 BOTANY. 



different 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. 



375. 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 resemblance. 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 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. 



376. Genus trillium, — Perianth of six parts: sepals 3, 

 herbaceous, persistent; petals colored. Stamens 6 (in two 

 whorls), anthers opening inward. Ovary 3-loculed, 3-6-angled; 

 stigmas 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. 



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

 dog-tooth violet (Erythronium americanum), shown in fig. 203, 

 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 elon- 

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

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



