382 COMPOSITAE. 



imbricated in a few rows, appressed; receptacle flattish to 

 hemispherical, naked, sometimes hairy; pappus none; corollas of 

 pistillate flowers slender and small, 2 or 3-toothed, of the perfect 

 flowers enlarged above, 5-toothed; akenes obovoid or oblong, 

 almost always glabrous. 

 Ours all perennial herbs. 



Disk-flowers perfect but sterile; marginal flowers pistillate and 

 fertile; leaves pinnately or bipinnately divided into nar- 

 now lobes. 

 Heads very numerous, small, greenish. A. canadensis. 



Heads rather few, large, brownish. A. borealis. 



Disk-flowers perfect, fertile; marginal flowers pistillate and 

 fertile; leaves not finely dissected. 

 Heads campanulate. A. tilesii. 



Heads cylindric. A . suhsdorfii. 



Artemisia canadensis Michx. Glabrous or canescently pubescent; stems 

 30-60 cm. high; lower leaves bipinnately divided into narrowly linear seg- 

 ments, the cauline less divided; inflorescence a narrow panicle; heads 4-6 mm. 

 broad; involucre hemispheric, green, glabrous or rarely pubescent. 



In rocky soil, rare in our limits; Coupeville, Washington, Gardner. 



Artemisia borealis wormskioldii Bess. Silky pubescent; stems 20-40 

 cm. high; lower leaves ternately or biternately divided into linear lobes; 

 cauline leaves linear, entire or 3-parted; heads racemose; involucre brownish, 

 pilose. 



Rocky places in the mountains, rare; Mount Rainier, Flett; Olympic 

 Mountains, Flett. 



Artemisia tilesii Ledeb. Herbage canescent with a thin tomentum; 

 stems erect or ascending, leafy, 60-90 cm. high; leaves oblong-lanceolate, 

 rarely entire, mostly incisely or laciniately cleft into narrow attenuate lobes, 

 thinly tomentose, becoming glabrous above; panicle loose, pyramidal; heads 

 hemispheric; involucre broadly campanulate, arachnoid when young, some- 

 times glabrate, more or less brownish. 



In the mountains at low altitudes. 



Artemisia suksdorfii Piper. Tufted; stems stiffly erect, .90-120 cm. high; 

 leaves numerous, oblong-lanceolate, acute, entire to sparingly dentate or 

 rarely incised, 6-10 cm. long, bright green above, white- tomentose beneath; 

 panicle pyramidal, dense, 30-60 cm. long; heads cylindric, 3—1 mm. high, 

 5-8-flowered; involucre pale green, glabrate, the tegules obtuse, hyaline- 

 margined. 



Abundant especially on bluffs along the seacoast. 



534. PETASITES. Sweet Coltsfoot. 



Perennial herbs with creeping rootstocks; leaves large, radical, 

 the cauline reduced to bracts; heads numerous, in a raceme or 

 corymb on the end of a scape-like stem; flowers whitish or 

 purplish, some imperfect; tegules in one row; akenes narrow, 

 5-10-ribbed; pappus soft, white. 



Leaves ovate or oblong, S-7-lobed, 5-10 cm. long; alpine plant. P. frigida. 

 Leaves reniform-orbicular, 7-9-cleft, very large, often 30 cm. or 



more broad; lowland plant. P. speciosa. 



