CO MPO SITAE. 1 01 7 



rather short-peduncled ; involucre depressed-hemispheric, its bracts oblong-lanceo- 

 late, obtuse, or the outer acute, slightly pubescent or ciliate; receptacle flat; flowers 

 yellow; marginal corollas with short oblique 3-toothed limbs; pappus a short 

 crown. Along roadsides, mostly escaped from gardens, N. S. and Ont. to S. Dak., 

 south to N. Car., Mo. and Kans. Nat. from Europe. July-Sept. 



Tanacetum vulgare crispum DC. Leaf-segments more incised and crisped. Occa- 

 sional, in similar situations; in some places more plentiful than the type. 



2. Tanacetum Huronense Nutt Lake Huron Tansy. (I. F. f. 3997.) 

 Villous-pubescent throughout, at least when young, less so when mature, 3-6 dm. 

 high. Leaves 2-pinnately divided, the lobes dentate or incised, acute, the lower 

 segments commonly smaller than the others; heads 1-8, on very stout pubescent 

 peduncles; involucre depressed-hemispheric ; marginal flowers with 3-5-lobed 

 limbs, often expanded into short rays; pappus a short crown. In moist soil, N. B. 

 to Hudson Bay, Me., Lake Superior, Alaska and Ore. July-Sept. 



89. ARTEMISIA L. 



Odorous herbs or shrubs, with alternate leaves, and small discoid, racemose, 

 spicate. glomerate or paniculate heads of greenish or yellowish flowers. Involucre 

 ovoid, oblong, or broadly hemispheric, its bracts imbricated in few series, the outer 

 gradually shorter. Receptacle naked or pubescent, not chaffy. Central flowers 

 perfect, sometimes sterile, with abortive ovaries and undivided styles, sometimes 

 perfect and fertile, with truncate style-branches; marginal flowers usually pistillate 

 and fertile, their corollas 2-3-toothed; or flowers all perfect and fertile in some 

 species. Anthers obtuse and entire at the base, often tipped with subulate appen- 

 dages. Achenes obovoid or oblong, 2 -ribbed or striate, rounded at the summit, 

 usually bearing a large epigynous disk. Pappus none. [Named for Artemisia, 

 wife of Mausolus.] About 200 species, natives of the northern hemtspnere and 

 southern S. Am. Besides the following, some 30 others occur in western N. Am. 



* Marginal flowers pistillate; central flowers perfect, sterile. 

 a. Biennial or perennial herbs. 

 Leaves pinnately dissected into narrowly linear lobes. 



Heads very numerous, 2 mm. broad; leaves mostly glabrous. 



1. A. c and at a. 

 Heads 4 mm. broad, in narrow panicles; leaves silky-pubescent. 



Heads few; involucre brown, mostly pubescent. 2. A. borealis. 



Heads numerous; involucre green, mostly glabrous. 3. A. Canadensis. 



Leaves linear, the lower sometimes 3-cleft or pinnately divided. 



Leaves glabrous. 4. A. dracunculoides. 



Leaves finely and densely pubescent. 5. A. glauca. 



b. Shrubby, silvery-canescent; heads small and numerous. 



6. A.fili/olia. 

 ** Marginalflowers pistillate; central flowers perfect, fertile. 

 a. Receptacle villous-pubescent. 

 Leaf-segments linear-filiform, short. 7. A./rigida. 



Leaf-segments oblong, or linear-oblong; introduced. 8. A. Absinthium. 



b. Receptacle glabrous, or sparingly pubescent. 

 Leaves dissected, glabrous or pubescent, green, not tomentose. 



Heads about 4 mm. broad, numerous in panicled racemes ; perennial. 



9. A. Abrotanum. 

 Heads about 2 mm. broad, paniculate or spicate; annuals. 



Leaves finely 2-3-pinnately divided; heads paniculate. 10. A. annua. 

 Leaves pinnately divided; segments pinnatifid; heads in leafy spikes. 



11. A. biennis. 

 Leaves densely white-canescent or tomentose, at least beneath. 



Leaves pinnatifid or dissected. 



Heads 6-8 mm. broad; racemose-glomerate; sea-beach plant. 



12. A. Stelleriana. 

 Heads 2-4 mm. broad, spicate-paniculate or racemose. 



Leaves deeply pinnatifid, the segments mostly incised. 



13. A. vulgaris. 

 Leaves finely dissected into short linear lobes. 14. A. Pontica. 

 Leaves pinnately parted into 5-7 narrow entire segments. 



15. A. A'ansana, 



