414 COMPOSITiE. Akomia. 



(10-12) perfect, with the corolla 5-toothed, nearly destitute of proper tube. 

 Scales of the involucre 5 or 6, equal, concave-carinate, obovate, nearly in a 

 single series, membranaceous. Receptacle convex, naked. Branches of the 

 style truncate. Achenia of the ray and disk similar, quadrangular, tapering 

 to the base, hairy on the angles. Pappus of about 12 oblong obtuse nerve- 

 less chaffy scales, distinct or slightly united at the base, much shorter than 

 the achenia, but almost equalling the very short corolla. — An aromatic an- 

 nual or biennial branching herb, nearly glabrous ; the branchlets glutinous. 

 Leaves linear ; the upper alternate, entire; the lower (often opposite) trifid 

 or somewhat pinnatifid ; the lobes filiform-linear. Heads corymbose, small. 

 Flowers yellow. 



A. tenuifolia (Nutt. ! 1. c.) 



St. Diego, California, near the coast, Nuttall! May.-— Lower leaves 2-3 

 inches long. Heads turbinate, 2-3 lines in diameter: the corolla of the pistil- 

 late flowers not longer than the perfect, both very short. Achenia and pappus 

 much as in Bahia and Cheenactis. — Although placed by Nuttall in Anthe- 

 mideae, Div. Cotuleas, this plant should rather find a place in the Subtribe 

 Helenieae. 



155. TANACETUM. Linn. ; Gcertn.fr. 1. 165 ; DC. prodr. 6. p. 127. 



Heads discoid, homogamous, with the flowers all tubular and perfect, or 

 heterogamous ; the marginal flowers pistillate, in a single series, 3-4-toolhed. 

 Scales of the involucre imbricated, dry. Receptacle convex, naked. Ache- 

 nia angled or ribbed, glabrous, with a large epigynous disk. Pappus either 

 none or minute, membranaceous, coroniform, entire or toothed, often unequal. 

 Herbs or suffruticose plants ; with alternate variously dissected leaves, and 

 solitary or corymbose (rather large) heads. Flowers yellow. 



§ 1. Heads (campanulate-hemispherical) heterogamous ; the terete ray -flow- 

 ers ^-toothed ; the disk-flowers 5-toothed. — Eutanacetum, DC. 



1. T. vulgare {Tiinn.) : stem herbaceous, erect, glabrous; leaves nearly 

 glabrous, bipinnately parted; the rachis and lobes incisely serrate; corymb 

 of numerous heads ; inner scales of the involucre scarious at the apex, ob- 

 tuse; pappus short, equal, 5-lobed. DC. — Lam. ill. t. 696, f. 1 ; Engl. hot. 

 1. 1229 ; Pursh, fl. 2. p. 522 ; Hook. ! fl. Bor.-Am. 1. p. 327 ; Darlingt. ! fl. 

 Cest. p. 492. 



(S. crispum (DC.) : leaves more incised and crisped. 



Naturalized abundantly in the Northern States ! and Canada ! July- 

 Sept. It — Tansey. 



§ 2. Heads {hemispherical, the disk convex in fruit,) heterogamous ; the ray- 

 flowers obcompressed, 3-5-lobed or toothed, slightly winged at the base ; the 

 disk-flowers 5-toothed. — Homalotes. (Omalanthus, Less. — Omalotes, 

 DC. — Homalotes, Endl.) 



2. T. Huronense (Nutt.) : hairy or almost tomentose when j'oung; stem 

 stout, herbaceous, striate-angled ; leaves bipinnately divided ; the lobes ob- 

 long, pinnatifid-incised, or often nearly entire, mucronate with a callous 

 point ; heads (large) corymbose, or rarely nearly solitary, on stout peduncles; 



