402 COMPOSITE. Tanacetum. 



93. TANACETUM, Linn. TANSY. 



Head many-flowered, heterogamous, with the flowers all tubular, the outermost 

 series pistillate, or rarely these wanting when the flowers are all perfect, mostly all 

 fertile. Involucre of numerous dry more or less scarious and brownish imbricated 

 and appressed scales. Receptacle flat or convex, naked. Corollas of the pistillate 

 flowers equally or obliquely 2 5-toothed ; of the perfect flowers 5-toothed. Akenes 

 generally about 5-ribbed or angled, or the marginal ones 3-sided ; the broad trun- 

 cate summit bearing a short and scarious coroniform pappus, or none. Strong- 

 scented herbs ; with alternate mostly compound or lobed leaves, and corymbose or 

 rarely solitary erect heads of yellow flowers. 



A moderately large genus in the Old World, widely represented by T. vulgare, Linn., the com- 

 mon Tansy, which, so far as we know, is not at all naturalized in California ; but there is a 

 stouter indigenous species on the coast related to it. Then, in the interior dry region there are 

 three or four peculiar species (section SpJiceromeria of Nuttall) related to certain others in Asia ; 

 the one found in California much approaches Artemisia. Ours are perennials. 



* Pappus evident : leaves very much dissected into innumerable divisions. 



1. T. Huronense, Nutt. Soft-hairy, usually much so when young : stems 

 stout, a foot or two high, very leafy : leaves twice or thrice pinnately dissected ; the 

 very small and numerous lobes oblong or linear and much crowded : heads large, 

 half an inch in diameter, on stout peduncles : corollas of the pistillate flowers rather 

 conspicuous and somewhat ray-like, 3 - 5-lobed, the tube flattened, slightly winged 

 at base : akenes very obscurely ribbed : pappus toothed. T. camphoratiim, Less. 

 T. Douglasii, DC. T. elegans, Decaisne, Fl. Serres, t. 1191. Omalanthus campho- 

 ratus, Less. Omalotes camphorata, DC. 



Sandhills, along the coast, from San Francisco to Puget Sound. Also on the Upper Great 

 Lakes, and from Hudson's Bay to the northern borders of Maine. 



* * Pappus none : leaves once or twice pinnately dissected into rather few divisions. 



2. T. potentilloides, Gray. ^Silvery-silky : stems numerous from a stout root, 

 diffuse or ascending, a span to a foot long, sparsely leafy : radical leaves twice pin- 

 nately divided and petioled, the cauline mostly sessile and once divided into linear 

 entire lobes ; uppermost reduced to nearly simple bracts : heads 3 to 6 in a loose 

 corymb (sometimes rather panicled), hemispherical, about 3 lines broad : scales of 

 the involucre about 10, broadly obovate, silky-tomentose : receptacle flattish, very 

 hirsute : flowers all fertile ; the pistillate ones with a small and slender 2-3- 

 toothed corolla : akenes obovate-turbinate, 3 5-angular, thin and vesicular, with 

 truncate broad summit. Proc. Am. Acad. ix. 204. Artemisia potentilloides, Gray, 

 Proc. Am. Acad. vi. 551. 



Eastern part of the Sierra Nevada, in Sierra Valley (Lemmon), and Carson City, Nevada, 

 Anderson. The corymbose heads as well as the broad and abrupt top of the akene refer this to 

 Tanacetum. The akene is thin and utricular, forming a loose investment to the seed : when 

 soaked it swells up and becomes jelly-like ; and its cells under the microscope show spiral 

 threads. 



94. ARTEMISIA, Linn. WORMWOOD. SAGE-BUSH. 



Head several r- many-flowered, heterogamous, with the flowers all tubular and the 

 outermost series pistillate, or homogamous by the absence of these ; the more 

 numerous perfect flowers either fertile or sterile. Scales of the involucre dry and 

 more or less scarious-margined, imbricated in few series, appressed. Receptacle flat- 

 ^ish, convex, or hemispherical, naked, sometimes hairy. Corollas of the pistillate 

 flowers slender and small, 2 - 3-toothed ; of the perfect flowers enlarged above, 



