Ta.vacetum. COMPOSITiE. 415 



inner scales of the involucre with brownish scarious margins ; ray-flowers 

 variable, often deeply cleft on the inside, with the rounded ligule slightly 

 3-toothed or 3-lobed, frequently with the limb 3-5-parted; pappus short, 

 toothed. — Null.! gen. 2. p. 141, Sf in trans. Amer. phil. soc. I.e. p. 401. 

 T. ? camphoratum, Less, in Linneea, 6 p. 521. T. Douglasii, DC! prodr. 

 6. p. 128. T. boreale, of the English gardens; Nutt. in trans, Amer. phil. 

 soc. I. c Omalanthus caraphoratus, Less. syn. p. 260 ; Hook. ! fl. Bor.- 

 Am. 1. p. 321. Omalotes camphorata, DC. prodr. 6. p. 83. 



Shores of Lakes Huron and Superior! north to York Factory on Hudson's 

 Bay! and west to Oregon! and California! — 1^ A stout plant, 1-3 feet 

 high ; the heads much larger than those of T. vulgare ; the disk strongly 

 convex in fruit. Rays slightly exserted. 



§ 3. Heads (obovoid) heterogamous ; the ray-floivers {about 5) truncate, 2-3- 

 toothed ; the disk-flowers b-toothed ; the central apparently infertile. — 



SpH-EROMERIA, Nutt. 



3. T. capitatum.: ctespitose, suflTrutescent, silky-canescent; leaves clustered 

 on a branched caudex, cuneiform, 3-5-parted or pedate ; those of the some- 

 what naked scapes nearly linear, entire or toothed at the apex ; heads nume- 

 rous, capitate ; scales of the involucre scarious ; pappus minute and irregu- 

 lar, denticulate, nearly obsolete in the disk-flowers. — Sphaeromeria capitata, 

 Nutt. ! in trans. Amer. phil. soc. {n. ser.) 7. p. 402. 



Rocky Mountains, on a hish hill, near the Red Butes of the Platte, towards 

 its northern sources on the Sweet Water, Nuttall ! June. — Plant growing 

 in dense tufis ; the scapes 3 or 4 inches high, terminated by the spherical 

 cluster of heads. Corolla, especially of the exterior flowers, becoming en- 

 larged and indurated at the base. — Odor agreeable, like that of Chammomile. 



4. T. Nuttallii : somewhat casspitose, silvery-canescent ; leaves cunei- 

 form, obtusely 3-lobed or toothed at the apex ; the lower crowded on the 

 branches of the woody caudex ; the upper scattered on the flowering stems ; 

 heads few (3-5) in a terminal capitate cluster ; scales of the involucre scari- 

 ous ; pappus very minute, in the disk-flowers obsolete. — Sphaeromeria 

 argentea, Nutt. ! I. c. 



Rocky INIountains, near the sources of the Platte and Colorado of the 

 West, Nuttall! July. — Shrub 4-5 inches high. Leaves half an inch long. 

 Flowers bright yellow. 



X Doubtful Species. 



5. T. pauciflorum (Richards.) : stem simple, with a single terminal head, 

 and sometimes another from the uppermost axil, longer than the bipinnate 

 and tripinnatifid villous sessile leaves ; the lobes narrow, rather obtuse ; 

 flowers all perfect. Richards, appx. Frankl. journ. ed. 2. p. 30 ; Hook. fl. 

 Bor.-Am. 1. p. 327 ; not of DC. 



Woody country, between lat. 54° and 64°, Richardson. — A foot high. 



156. ARTEMISIA. Linn.; Besser; DC. prodr. 6. p. 93. 



Heads discoid, few-many-flowered, heterogamous, with the central flowers 

 perfect (either fertile, or sterile by the abortion of the ovary,) and 5-toothed, 

 and the marginal pistillate in a single series, with a tubular 3-toothed corolla ; 

 or sometimes homogamous, with the flowers all perfect. Scales of the in- 

 volucre imbricated, mostly dry and with scarious margins. Receptacle 



