Tanacetum L.

Herbs, annual orperennial. Leaves usually pinnatisect. Heads yellow, heterogamous or homogamous, disciform, corymbose (rarely large, long peduncled and solitary). Involucral bracts many-seriate, appressed, margins often scarious and brown; outer smaller. Receptacle flat or convex, naked. Outer florets absent or female, fertile, 1-seriate, terete or compressed, 2 - 3-fid. Disc florets hermaphrodite, fertile, tube stout, cylindric; limb 5-fid. Anther bases obtuse, entire. Style arms of hermaphrodite florets with truncate penicillate tips. Achenes compressed, 5-angled or ribbed, or of the outer florets triquetrous, truncate. Pappus annular or coroniform or absent, rarely with a dimidiate auricle.

North temperate regions; 70 species, 12 in India.

KEY TO THE SPECIES

1a. Leaves cuneiform, 3-tid

6. Tanacetum gossypinum

b. Leaves 1 - 3-pinnatisect, or pinnatipartite

2

2a. Leaves all cauline; stems or branches all flowering

3

b. Leaves radical and cauline; only elongating stems from root flowering, the rest and floweriess

7

3a. Involucral bracts nearly glabrous

4

b. Involucral bractas pubescent to woodly

5

4a. Heads ca 6 mm in diam.; stems strict, leafy upwards; leaves pinnatisect

4. Tanacetum fruticulosum

b. Heads ca 4 mm in diam.; stems corymbosely branched above; leaves palmately pinnatipartite

5. Tanacetum gracile

5a. Receptacle conical; stem sparsely leafy; leaves 1 - 2.5 cm long;

1. Tanacetum artemisioides

b. Receptacle convex or hemispheric; stem densely leafy upwards; leaves 0.6 - 1.25 cm long;

6

6a. Slems elongate, hoary or woolly, few, robust; leaves 1-3-pinnatisect; involucral bracts broadly oblong; achenes rounded at the tip

8. Tanacetum nubigenum

b. Stems short, tomentose, very many. crowded; leaves palmately pinnatisect; involucrall bracts orbicular, pubescent; achenes with a minute terminal cup

10. Tanacetum tibeticum

7a. Stems short, tomentose, very many. crowded; leaves palmately pinnatisect; involucrall bracts orbicular, pubescent; achenes with a minute terminal cup

7. Tanacetum nanum

b. Tall and robust herbs, rarely small; radical leaves 2.5 - 25 cm long; segments subfiliform to linear, acute or obtuse

8

8a. Stem 0.6 - 1.2 m tall; leaves pinnatipartite; segments rigidly bristly at the apices; pappus of an acutely dentate corona

12. Tanacetum tripinnatifidum

b. Stem up to 60 cm high; leaves palmately or 2-pinnatisecti segments linear or linear ovoid or subfiliform, acute or obtuse; pappus absent

9

9a. Stems few or many from the woody rootstock; leaves palmately pinnatifid; involucral bracts broadly ovate

11. Tanacetum tomentosum

b. Stem solitary or subsolitary from the woody rootstock; leaves 2-pinnatisect; involucral bracts oblong or linear oblong

10

10a. Radical leaves 12-25 cm long, slender, linear; involucral bracts with broad scarious purple margins

2. Tanacetum dolichophyllum

b. Radical leaves 5-10 cm long, oblong or oblong-slender in outline; involucral bracts with narrow scarious pale margins

11

11a. Stem softly tomentose; involucral bracts densely woolly; florets numerous

9. Tanacetum robustum

b. Stem silky tomentose or hoary; involucral bracts densely pubescent; florets ca 20

3. Tanacetum falconeri

List of Lower Taxa