Robert W. Freckmann Herbarium


KEY to the WISCONSIN ASTERACEAE

 

Tribe 7. ANTHEMIDEAE - chamomile tribe

 

(Source: Mickelson and Iltis, 1966; Fernald, 1950; Gleason and Cronquist, 1991;

FNA, 2006.)

 

1.   Receptacle chaffy; heads radiate.

 

2.    Heads small, 5 mm or less in diameter, densely corymbose; receptacle flat; achenes compressed

.........  ACHILLEA - yarrow.

 

2.    Heads rather large, 1‑4 cm in diameter, solitary and terminal on long peduncles; receptacle conic at maturity; achenes terete or angled.

 

3. Ray florets white; disk 0.5‑1.2 cm in diameter .

....  ANTHEMIS - chamomile, dog-fennel.

 

3. Ray florets yellow; disk 1‑2 cm in diameter; rare adventive .

....  COTA - marguerite.

 

1.   Receptacle naked or villous; heads radiate, disciform or discoid.

 

4. Inflorescence paniculate, racemose or spike-like with inconspicuous (2‑8 mm long) disciform or discoid heads; florets green

.........  ARTEMISIA - wormwood.

 

4.  Inflorescence corymbose OR heads terminal on long peduncles; ray florets showy, yellow or white (sometimes obsolete).

 

5. Receptacle conic at maturity; leaves pinnatisect

....  MATRICARIA & TRIPLEUROSPERMUM - wild chamomile.

 

5.    Receptacle flat or low-convex.

 

6.    Heads several or numerous, in corymbs, disk 4-9 mm wide, with or without rays; leaves often highly lobed         

........  TANACETUM - tansy.

 

6.    Heads solitary at tips of stem or long branches, large, disk 1-2.5 cm wide, with conspicuous white rays; leaves toothed to lobed.

 

7.  Heads solitary on long, slender, naked peduncles; upper leaves strongly reduced or lacking; stems slender, 4‑6 dm tall; abundant throughout  

....  LEUCANTHEMUM

 

7.  Heads few to many at end of robust, leafy, 1‑2 m tall stems; peduncles 3‑15 cm long; rare garden escape  

....  LEUCANTHEMELLA

 

 

ACHILLEA - yarrow

 

(s = 9)

 

1.   Leaves undissected, serrulate; plant glabrate to subglabrous; rare adventive (s = 2x) .

...........  A. Ptarmica - sneezeweed.

 

1.   Leaves finely dissected into linear segments; plant tomentose; ubiquitous throughout (s = 2x, 3x, 4x, 5x, 6x, 7x, 8x)

....  A. Millefolium - common yarrow, milfoil.

 

2. Leaves flat, the relatively broad ultimate segments all nearly in the same plane; hexaploid; less common introduced taxon (mostly s = 6x)

.........  subsp. Millefolium.

 

2. Leaves airily 3‑dimensional, the ultimate segments narrower and disposed in various planes; tetraploid; very common native taxon (mostly s = 4x)

.........  subsp. lanulosa.

 

 

 

ANTHEMIS - chamomile, dog-fennel

 

(s = 2x; x = 9)

 

1.   Ray florets sterile; receptacle chaffy only toward the middle; ill-scented; very common, especially southern Wisconsin

 ............... A. Cotula - dog-fennel, stinking camomile.

 

1.   Ray florets fertile; receptacle chaffy throughout; odorless

...........  A. arvensis - corn chamomile.

 

 ARTEMISIA - wormwood

 

(x = 9)

 

1.   Receptacle hairy; leaves white-silky canescent; plants perennial and somewhat woody at base.

 

2. Leaves short, 1‑2 cm long, the segments filiform, 0.5‑1 mm wide; flowering stems ascending, to 5 dm tall, the vegetative stems forming mats; inflorescence a narrow panicle; very local on Mississippi River bluffs from Pierce Co. to Trempealeau Co., rarely weedy elsewhere (s = 2x)

....  A. frigida - prairie sage-wort.

 

2. Leaves 5‑15 cm long, the segments 2‑3 mm wide; flowering stems erect, to 9 dm tall; inflorescence a leafy panicle; sporadic adventive (s = 2x)

....  A. Absinthium - common wormwood, absinthe sage-wort.

 

1.   Receptacle naked; leaves tomentose to glabrous; plants annual, biennial or perennial.

 

3.    Disk florets staminate, their ovaries aborting; adult plants usually glabrous.

 

4. Biennial with a taproot; first year's lower leaves forming a basal rosette; leaves tomentose-glabrate; involucre 2‑3.5 mm long; common in sandy areas (s = 2x, 4x [within species])

.....  A. campestris subsp. caudata - field wormwood or sage-wort, beach wormwood.

 

4. Robust perennial from a rootstock; lower leaves not in a rosette; leaves glabrous; involucre 2 mm long; very rare and sporadic (s = 2x)

..  A. Dracunculus - tarragon, estragon.

 3.    Disk florets producing achenes.

 

5.    Leaves glabrous or glabrate, 2‑3 times pinnatisect or pinnatifid.

 

6.    Perennial shrub; involucre 2‑2.5 mm long; bracts canescent or tomentose; rare garden escape (not naturalized)  (s = 2x)         

........  A. Abrotanum - southernwood.

 

6.    Annual or biennial herbs; involucre 1‑2 mm long; bracts glabrous.

 

7.  Inflorescence a dense racemose panicle with many spike-like branches from the leaf axils; heads erect; common weed (s = 2x)  

....  A. biennis - biennial wormwood or sage-wort.

 

7.  Inflorescence a broad terminal panicle with nodding heads; rare annual weed (s = 2x)  

....  A. annua - annual wormwood or sage-wort.

 

5.    Leaves tomentose at least on one surface, simple or dissected.

 

8.    Leaves unlobed and linear-lanceolate, the margins regularly serrate to entire in the inflorescence, densely white-tomentose beneath, bright green-glabrous above; moist deep-soil prairies (s = 4x)         

........  A. serrata - saw-tooth wormwood.

 

8.     Leaves deeply lobed or cut, OR entire with the margins irregularly toothed.

 

9.  Leaves delicately divided, the segments filiform, gray-green pubescent; rare garden escape (s = 2x)  

....  A. pontica - Roman wormwood.

 

9.  Leaf segments broader or leaves entire.

 

 

10.  Leaves green-glabrate above, white-tomentose beneath, coarsely lobed; rare weed, eastern Wisconsin (s = 2x, 4x, 40, 6x)       

......  A. vulgaris - mugwort, common wormwood.

 

10.  Leaves pubescent on both surfaces.

 

11.  Involucre 2‑4 mm long; leaves entire or irregularly toothed, densely white-tomentose beneath, tomentose to glabrate above; common prairie species (s = 2x, 4x)

...........  A. ludoviciana subsp. ludoviciana - white sage, western mugwort.

 

11.  Involucre 5‑8 mm long; leaves obtusely lobed, densely creamy white wooly; rare garden escape on Lakes Michigan and Superior (s = 2x)

...........  A. Stelleriana - beach wormwood, dusty miller.

 

COTA - marguerite

 

(s = 2x; x = 9)

 

........  C. (Anthemis) tinctoria - golden marguerite, yellow chamomile.

 

 

LEUCANTHEMELLA

 

(s = 2x; x = 9)

 

........  Leucanthemella (Chrysanthemum) serotina - giant daisy.

 

 

LEUCANTHEMUM

 

(s = 2x, 4x, 6x, 8x, 10x; x = 9)

 

........  Leucanthemum vulgare (Chrysanthemum Leucanthemum) - common or ox-eye daisy.

 

 


 

MATRICARIA & TRIPLEUROSPERMUM - wild chamomile

 

1.   Ray florets none; disk florets greenish, 4‑lobed; heads short-stalked; achenes marked by elongate red-brown oil glands; very common throughout

...........  M. discoidea (M. matricarioides) - pineapple-weed.

 

1.   Ray florets white; disk florets yellow, 5‑lobed; heads long-stalked.

 

2. Receptacle conic at maturity; achenes ribbed, smooth, unmarked; involucre 2‑3 mm long; rare adventive (See also Anthemis Cotula)

....  M. Chamomilla (M. recutita) - sweet false camomile.

 

2. Receptacle hemispheric at maturity; achenes prominently ribbed, transversely rugulose or tuberculate with apical oil glands; involucre 3.5‑6 mm long; rare adventive on Lake Superior shores

.........  Tripleurospermum (Matricaria) maritimum - scentless camomile.

 

 

TANACETUM - tansy

 

(x = 9)

 

1.   Rays white, conspicuous, minute or absent; leaves largely unlobed OR 1-2 pinnatifid with broad ultimate segments.

 

2. Heads radiate, the rays 4‑8 mm long; leaves 1-2 pinnatifid; rare garden escape (s = 2x)

.....  T. (Chrysanthemum) Parthenium - feverfew.

 

2. Heads discoid or rays minute; leaves crenate, rarely lobed at base; rare adventive (s = 2x, 6x)

.... Tanacetum (Chrysanthemum) Balsamita - costmary, mint-geranium.

 

1.   Rays yellow and short (2‑4 mm) or absent; leaves 2-3 pinnatifid with narrow ultimate segments.

 

3. Heads disciform, 25‑100 or more in dense corymbs, 7‑10 mm in diam.; leaves glabrate; plants in dense, many stemmed clumps; common introduced weed (s = 2x)

.....  T. vulgare - common tansy, golden-buttons.

 

3. Heads radiate, 3‑17 in loose corymbs, 1‑2 cm in diam., rays 2‑4 mm long; leaves tomentose; stems solitary; rare on inner beaches of Lake Michigan, Door Co. (s = 6x)

.....  T. bipinnatum subsp. huronense - eastern or Lake Huron tansy.


         
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