Asteraceae - composite family
Mount Desert Island is home to 79 species plus 2 hybrids in 44 genera that grow without cultivation. Click on a link below or scroll down for more information.
Achillea (2 species)
Achillea millefolium - common yarrow (common [see note 1 at bottom of page)
Achillea ptarmica - pearl yarrow (rare)
Ambrosia (1 species)
Ambrosia artemisiifolia - common ragweed (common)
Anaphalis (1 species)
Anaphalis margaritacea - pearly everlasting (occasional)
Antennaria (2 species)
Antennaria howellii ssp. canadensis - small pussytoes (uncommon)
Antennaria howellii ssp. neodioica - small pussytoes (occasional)
Antennaria neglecta - field pussytoes (uncommon)
Anthemis (1 species)
Anthemis cotula - stinking chamomile (uncommon)
Arctium (1 species)
Arctium minus - common burdock (occasional)
Arnoseris (1 species)
Arnoseris minima - lamb-succory (rare)
Artemisia (1 species)
Artemisia vulgaris - common wormwood (common)
Bidens (1 species)
Bidens frondosa - Devil's beggar-ticks (occasional)
Centaurea (1 species)
Centaurea nigra - black knapweed (uncommon)
Cichorium (1 species)
Cichorium intybus - chicory (uncommon)
Cirsium (3 species)
Cirsium arvense - creeping thistle (common)
Cirsium muticum - swamp thistle (uncommon)
Cirsium vulgare - common thistle (common)
Doellingeria (1 species)
Doellingeria umbellata - tall white-aster (common)
Erechtites (1 species)
Erechtites hieraciifolius - American burnweed (occasional)
Erigeron (3 species)
Erigeron annuus - annual fleabane (occasional)
Erigeron canadensis - Canada fleabane (occasional)
Erigeron strigosus - rough fleabane (occasional)
Eupatorium (1 species)
Eupatorium perfoliatum - boneset thoroughwort (occasional)
Eurybia (2 species)
Eurybia macrophylla - large-leaved wood-aster (common)
Eurybia radula - rough wood-aster (occasional)
Euthamia (1 species)
Euthamia graminifolia - common grass-leaved-goldenrod (common)
Galinsoga (1 species)
Galinsoga quadriradiata - common quickweed (common)
Gnaphalium (1 species)
Gnaphalium uliginosum - common quickweed (common)
Helianthus (1 species)
Helianthus tuberosus - Jerusalem artichoke (uncommon)
Hieracium (9 species and 1 hybrid)
Hieracium aurantiacum - orange hawkweed (common)
Hieracium caespitosum - yellow hawkweed (common)
Hieracium xfloribundum - a hawkweed hybrid (occasional)
Hieracium kalmii - Canada hawkweed (common)
Hieracium lachenalii - common hawkweed (common)
Hieracium murorum - wall hawkweed (occasional)
Hieracium paniculatum - panicled hawkweed (uncommon)
Hieracium pilosella - mouse-ear hawkweed (common)
Hieracium sabaudum - Savoy hawkweed (uncommon)
Hieracium scabrum - rough hawkweed (uncommon)
Jacobaea (1 species)
Jacobaea vulgaris - tansy ragwort (rare)
Lactuca (2 species)
Lactuca biennis - tall blue lettuce (uncommon)
Lactuca canadensis - tall lettuce (uncommon)
Lapsana (1 species)
Lapsana communis - common nipplewort (occasional)
Leucanthemum (1 species)
Leucanthemum vulgare - ox-eye daisy (common)
Matricaria (1 species)
Matricaria discoidea - rayless chamomile (common)
Mycelis (1 species)
Mycelis muralis - wall-lettuce (occasional)
Nabalus (2 species)
Nabalus altissimus - tall rattlesnake-root (occasional)
Nabalus trifoliolatus - three-leaved rattlesnake-root (common)
Oclemena (2 species and 1 hybrid)
Oclemena acuminata - sharp-toothed nodding-aster (common)
Oclemena x blakei - a nodding-aster hybrid (occasional)
Oclemena nemoralis - bog nodding-aster (occasional)
Packera (1 species)
Packera schweinitziana - golden groundsel (rare)
Petasites (1 species)
Petasites frigidus - northern sweet-coltsfoot (rare)
Pseudognaphalium (1 species)
Pseudognaphalium obtusifolium - blunt-leaved rabbit-tobacco (uncommon)
Rudbeckia (1 species)
Rudbeckia hirta - black-eyed coneflower (occasional)
Scorzoneroides (1 species)
Scorzoneroides autumnalis - fall-dandelion (common)
Senecio (2 species)
Senecio sylvaticus - woodland ragwort (occasional)
Senecio vulgaris - common ragwort (occasional)
Silphium (1 species)
Silphium perfoliatum - cup-plant rosinweed (rare)
Solidago (11 species)
Solidago bicolor - white goldenrod (common)
Solidago canadensis - Canada goldenrod (common)
Solidago flexicaulis - zig-zag goldenrod (uncommon)
Solidago gigantea - smooth goldenrod (uncommon)
Solidago juncea - early goldenrod (occasional)
Solidago nemoralis - gray goldenrod (occasional)
Solidago puberula - downy goldenrod (common)
Solidago rugosa - common wrinkle-leaved goldenrod (common)
Solidago sempervirens - seaside goldenrod (common)
Solidago simplex - Rand's goldenrod (common)
Solidago uliginosa - bog goldenrod (occasional)
Sonchus (3 species)
Sonchus arvensis - field sow-thistle (occasional)
Sonchus asper - spiny-leaved sow-thistle (common)
Sonchus oleraceus - common sow-thistle (occasional)
Symphyotrichum (5 species)
Symphyotrichum cordifolium - heart-leaved American-aster (occasional)
Symphyotrichum lateriflorum - calico American-aster (common)
Symphyotrichum novae-angliae - New England American-aster (occasional)
Symphyotrichum novi-belgii - New York American-aster (common)
Symphyotrichum puniceum - purple-stemmed American-aster (occasional)
Tanacetum (1 species)
Tanacetum vulgare - common tansy (occasional)
Taraxacum (1 species)
Taraxacum officinale - common dandelion (common)
Tragopogon (1 species)
Tragopogon pratensis - meadow goat’s-beard (uncommon)
Tussilago (1 species)
Tussilago farfara - coltsfoot (uncommon)
In the Asteraceae, what a casual observer perceives to be a single flower is really many flowers growing together in what is called a capitulum. The common dandelion and the ox-eye daisy are two familiar examples.
Each flower in the Asteraceae is one of two distinct forms: a disk flower or a ray flower. In each species, a capitulum has either all disk flowers or all ray flowers or both disk and ray flowers. The ox-eye daisy (Leucanthemum vulgare) is a species with both kinds of flowers in a capitulum: white ray flowers around the perimeter and yellow disk flowers in the interior. Ray flowers and disk flowers are relatively easy to differentiate.
On Mount Desert Island, all the species in a genus have the same composition of ray and disk flowers, with the exception of the genus Senecio, in which Senecio sylvaticus has both ray and disk flowers and Senecio vulgaris has only disk flowers. The table below arranges the genera according to which kind(s) of flowers occur in a capitulum.
Step 1 in identifying which species you have is to determine which of the three groups your plant falls into. Choose from the following three options, and you will be taken to an identification table for that group:
both ray and disk flowers
ray flowers only
disk flowers only
| red font = unique or uncommon character states | character 1 | character 2 | character 3 | character 4 |
| Achillea | ||||
| Anthemis | ||||
| Doellingeria | ||||
| Erigeron | ||||
| Eurybia | ||||
| Euthamia | ||||
| Galinsoga | ||||
| Helianthus | ||||
| Jacobaea | ||||
| Leucanthemum | ||||
| Oclemena | ||||
| Packera | ||||
| Petasites | ||||
| Rudbeckia | ||||
| Senecio sylvaticus | ||||
| Silphium | ||||
| Solidago | ||||
| Symphyotrichum | ||||
| Tussilago |
| red font = unique or uncommon character states | leaf position (note: all cauline leaves are alternate) |
ray flower color | capitula per stem | capitulum diameter |
| Arnoseris | basal | yellow | 1–3 | 12–18 mm |
| Cichorium | cauline | light blue | 1–3 | 25–40 mm |
| Hieracium | basal, cauline | red-orange, yellow | 1–many | 10–15 mm |
| Lactuca | cauline | pale blue, white, yellow | 13–55 | 6–10 mm |
| Lapsana | cauline | yellow | 4 or more | 10–15 mm |
| Mycelis | basal, cauline | yellow | 4 or more | to 10 mm |
| Nabalus | cauline | white, cream | 4 or more | {?} |
| Scorzoneroides | basal | yellow | 1 to many | approximately 25 mm |
| Sonchus | cauline | yellow | 4 or more | 15–50 mm |
| Taraxacum | basal | yellow | 1 | 20–50 mm |
| Tragopogon | cauline | yellow | 1 | to 60 mm |
| red font = unique or uncommon character states | arrangement of cauline leaves | leaf type | disk flower color | character 4 |
| Ambrosia | opposite below, alternate above |
compound | yellow-green | |
| Anaphalis | alternate | simple | yellow, [white?] | |
| Antennaria | alternate | simple | white | |
| Arctium | alternate | simple | purple | |
| Artemisia | alternate | simple, compound | yellow, green | |
| Bidens | opposite | simple, compound | yellow, orange | |
| Centaurea | alternate | simple | purple | |
| Cirsium | alternate | simple | pink, purple, rose | |
| Erechtites | alternate | simple | white | |
| Eupatorium | opposite | simple | white | |
| Gnaphalium | alternate | simple | blue, purple | |
| Matricaria | alternate | compound | yellow | |
| Pseudognaphalium | alternate | simple | yellow | |
| Senecio vulgaris | alternate | simple | yellow | |
| Tanacetum | alternate | compound | yellow |
Achillea (yarrow)
[information to be added]
| leaf division | leaf width | capitulum width | ray flowers per capitulum | disk flower color | |
| Achillea millefolium | finely dissected | 10–25 mm | 4–6 mm | usually 5 | white |
| Achillea ptarmica | finely toothed | 2–6 mm | 12–19 mm | 6–15 | greenish white |
Achillea millefolium (common yarrow) - The compound leaves are dissected into fine segments (below left), and the corolla of both the ray flowers and the disk flowers are white (below right).
(click on an image to enlarge)
Achillea ptarmica (pearl yarrow) - [information to be added]
Ambrosia (ragweed)
[information to be added]
Ambrosia artemisiifolia (common ragweed) - [information to be added]
(click on image to enlarge)
Anaphalis (everlasting)
[information to be added]
Anaphalis margaritacea (pearly everlasting) - [information to be added]
(click on image to enlarge)
[capitula]
(click on image to enlarge)
Antennaria (pussytoes)
[information to be added]
| basal leaf pubescence | color of upper surface of basal leaves | |
| Antennaria howellii | glabrous | bright green |
| Antennaria neglects | woolly | dull green |
Antennaria howellii (small pussytoes) - [information to be added]
Antennaria neglecta (field pussytoes) - [information to be added]
Anthemis (chamomile)
[information to be added]
Anthemis cotula (stinking chamomile) - [information to be added]
Arctium (burdock)
[information to be added]
Arctium minus (common burdock) - Perhaps surprisingly, the petiole of the very large leaves is hollow. This is not, however, true of all species of Arctium.
(click on image to enlarge)
Arnoseris (lamb-succory)
[information to be added]
Arnoseris minima (lamb-succory) - [information to be added]
Artemisia (wormwood)
[information to be added]
Artemisia vulgaris (common wormwood) - [information to be added]
(click on image to enlarge)
lower leaves adaxial surface (lower left) and abaxial surface (lower right)
(click on an image to enlarge)
Bidens (beggar-ticks)
[information to be added]
Bidens frondosa (Devil's beggar-ticks) - [information to be added]
Centaurea (knapweed)
[information to be added]
Centaurea nigra (black knapweed) - [information to be added]
Cichorium (chicory)
[information to be added]
Cichorium intybus (chicory) - [information to be added]
Cirsium (thistle)
[information to be added]
| capitulum length | disk corolla color | |
| Cirsium arvense | 1–2.5 cm | pale pink, white |
| Cirsium muticum | >3.5 cm | deep rose-purple |
| Cirsium vulgare | 2.5–5 cm | purple to pink |
Cirsium arvense (creeping thistle) - [information to be added]
Cirsium muticum (swamp thistle) - [information to be added]
Cirsium vulgare (common thistle) - [information to be added]
(click on image to enlarge)
Doellingeria (white-aster)
[information to be added]
Doellingeria umbellata (tall white-aster) - [information to be added]
(click on image to enlarge)
Stem and leaves (lower left); capitulescence (lower right)
(click on an image to enlarge)
Erechtites (burnweed)
[information to be added]
Erechtites hieraciifolius (American burnweed) - [information to be added]
Erigeron (fleabane)
[information to be added]
Erigeron annuus (annual fleabane) - [information to be added]
Erigeron canadensis (Canada fleabane) - [information to be added]
Erigeron strigosus (rough fleabane) - [information to be added]
Eupatorium (thoroughwort)
[information to be added]
Eupatorium perfoliatum (boneset thoroughwort) - The oppositely arranged leaves of each pair are fused at their base, giving the impression of a single leaf being pierced by the stem; hence, the specific epithet perfoliatum.
(click on image to enlarge)
Eurybia (wood-aster)
[information to be added]
Eurybia macrophylla (large-leaved wood-aster) - Long before any capitula have appeared, the very large leaves of this species are evident, effectively forming a ground cover.
(click on image to enlarge)
The capitula begin to appear in mid- to late August.
(click on an image to enlarge)
Eurybia radula (rough wood-aster) - [information to be added]
Euthamia (grass-leaved goldenrod)
[information to be added]
Euthamia graminifolia (common grass-leaved goldenrod) - [information to be added]
(click on image to enlarge)
Galinsoga (quickweed)
[information to be added]
Galinsoga quadriradiata (common quickweed) - [information to be added]
Gnaphalium (cudweed)
[information to be added]
Gnaphalium uliginosum (brown cudweed) - [information to be added]
Helianthus (sunflower)
[information to be added]
Helianthus tuberoses (tuberous sunflower) - [information to be added]
Hieracium (hawkweed)
[information to be added]
Hieracium aurantiacum (orange hawkweed) - [information to be added]
(click on an image to enlarge)
Hieracium caespitosum (yellow hawkweed) - [information to be added]
Hieracium xfloribundum (a hawkweed hybrid) - [information to be added]
Hieracium kalmii (Canada hawkweed) - [information to be added]
Hieracium lachenalii (common hawkweed) - [information to be added]
Hieracium murorum (wall hawkweed) - [information to be added]
Hieracium paniculatum (panicled hawkweed) - [information to be added]
Hieracium pilosella (mouse-ear hawkweed) - [information to be added]
Hieracium sabaudum (Savoy hawkweed) - [information to be added]
Hieracium scabrum (rough hawkweed) - [information to be added]
Jacobaea (ragwort)
[information to be added]
Jacobaea vulgaris (tansy ragwort) - [information to be added]
Lactuca (lettuce)
[information to be added]
Lactuca biennis (tall blue lettuce) - [information to be added]
Lactuca canadensis (tall lettuce) - [information to be added]
Lapsana (nipplewort)
[information to be added]
Lapsana communis (common nipplewort) - [information to be added]
Leucanthemum (daisy)
[information to be added]
Leucanthemum vulgare (ox-eye daisy) - [information to be added]
(click on an image to enlarge)
Matricaria (chamomile)
[information to be added]
Matricaria discoidea (rayless chamomile) - [information to be added]
(click on image to enlarge)
Mycelis (wall-lettuce)
[information to be added]
Mycelis muralis (wall-lettuce) - [information to be added]
Nabalus (rattlesnake-root)
[information to be added]
Nabalus altissimus (tall rattlesnake-root) - [information to be added]
Nabalus trifoliolatus (three-leaved rattlesnake-root) - [information to be added]
(click on an image to enlarge)
Oclemena (nodding-aster)
[information to be added]
Oclemena acuminata (sharp-leaved nodding-aster) - [information to be added]
(click on an image to enlarge)
Oclemena xblakei (a nodding-aster hybrid) - [information to be added]
Oclemena nemoralis (bog nodding-aster) - [information to be added]
Packera (groundsel)
[information to be added]
Packera schweinitziana (golden groundsel) - [information to be added]
Petasites (sweet-coltsfoot)
[information to be added]
Petasites frigidus (northern sweet-coltsfoot) - [information to be added]
Pseudognaphalium (rabbit-tobacco)
[information to be added]
Pseudognaphalium obtusifolium (blunt-leaved rabbit-tobacco) - [information to be added]
Rudbeckia (coneflower)
[information to be added]
Rudbeckia hirta (black-eyed coneflower) - [information to be added]
(click on image to enlarge)
Scorzoneroides (fall-dandelion)
[information to be added]
Scorzoneroides autumnalis (fall-dandelion) - [information to be added]
(click on an image to enlarge)
Senecio (ragwort)
[information to be added]
Senecio sylvaticus (woodland ragwort) - [information to be added]
Senecio vulgaris (common ragwort) - [information to be added]
Silphium (rosinweed)
[information to be added]
Silphium perfoliatum (cup-plant rosinweed) - [information to be added]
Solidago (goldenrod)
[information to be added]
| red font = unique character state (or nearly so) | stem below capitulescence | leaf concentration | leaf margin | leaf length | leaf width | inflorescence | ray flower color | ray flower number |
| Solidago bicolor | pubescent | basally disposed | longest usually toothed | 8–20 cm | 1.5–6 cm | spike-like | white | 7–9 |
| Solidago canadensis | pubescent (glabrous near base) |
chiefly cauline | sharply toothed | 3–15 cm | 0.5–2.2 cm | secund | yellow | 10–17 |
| Solidago flexicaulis | pubescent (grooved) |
chiefly cauline | sharply toothed | 7–15 cm | 3–10 cm | axillary clusters | yellow | 3–4 |
| Solidago gigantea | glabrous (glaucous) |
chiefly cauline | sharply toothed | 6–17 cm | 1–4.5 cm | secund | yellow | 8–17 |
| Solidago juncea | glabrous (green, branching) |
basally disposed | more or less serrate | 15–40 cm | 2–7.5 cm | secund | yellow | 7–12 |
| Solidago nemoralis | densely pubescent | basally disposed | entire or bluntly toothed | 5–25 cm | 0.8–4 cm | secund | yellow | 5–9 |
| Solidago puberula | densely pubescent (often purple) |
basally disposed | serrate | 5–15 cm | 1–3.5 cm | elongate | yellow | 9–16 |
| Solidago rugosa | pubescent | chiefly cauline | sharply toothed | 3.5–13 cm | 1.3–5 cm | secund | yellow | 6–11 |
| Solidago sempervirens | glabrous | basally disposed | entire | 10–40 cm | 1–6 cm | secund | yellow | 8–17 |
| Solidago simplex | pubescent | basally disposed | sharply toothed | 2–30 cm | 0.4–4 cm | rounded to elongate | yellow | 7–12 |
| Solidago uliginosa | glabrous | basally disposed | basal leaves usually finely toothed | 6–35 cm | 0.6–6 cm | elongate | yellow | 1–8 |
Solidago bicolor (white goldenrod) - [information to be added]
(click on image to enlarge)
Solidago canadensis (Canada goldenrod) - [information to be added]
Solidago flexicaulis (zig-zag goldenrod) - [information to be added]
(click on image to enlarge)
Solidago gigantea (smooth goldenrod) - [information to be added]
Solidago juncea (early goldenrod) - [information to be added]
Solidago nemoralis (gray goldenrod) - [information to be added]
Solidago puberula (downy goldenrod) - [information to be added]
Solidago rugosa (common wrinkle-leaved goldenrod) - [information to be added]
Solidago sempervirens (seaside goldenrod) - [information to be added]
Solidago simplex (Rand's goldenrod) - [information to be added]
Solidago uliginosa (bog goldenrod) - [information to be added]
Sonchus (sow-thistle)
[information to be added]
Sonchus arvensis (field sow-thistle) - [information to be added]
Sonchus asper (spiny-leaved sow-thistle) - [information to be added]
Sonchus oleraceus (common sow-thistle) - [information to be added]
Symphyotrichum (American-aster)
[information to be added]
Symphyotrichum cordifolium (heart-leaved American-aster) - [information to be added]
Symphyotrichum lateriflorum (calico American-aster) - [information to be added]
Symphyotrichum novae-angliae (New England American-aster) - [information to be added]
Symphyotrichum novi-belgii (New York American-aster) - [information to be added]
Symphyotrichum puniceum (purple-stemmed American-aster) - [information to be added]
Tanacetum (tansy)
[information to be added]
Tanacetum vulgare (common tansy) - [information to be added]
(click on an image to enlarge)
Taraxacum (dandelion)
[information to be added]
Taraxacum officinale (common dandelion) - [information to be added]
(click on image to enlarge)
Tragopogon (goat’s-beard)
[information to be added]
Tragopogon pratensis (meadow goat’s-beard) - [information to be added]
(click on image to enlarge)
Tussilago (coltsfoot)
[information to be added]
Tussilago farfara (coltsfoot) - Unlike most plants, the flowers of Tussilago, in capitula as they occur in the Asteraceae, appear before the leaves develop.
(click on an image to enlarge)
When the flowers begin to senesce, the leaves begin to appear.
(click on an image to enlarge)
Note:
1. Frequency designations are from the paper “Vascular flora of the Acadia National Park region, Maine” by Craig W. Greene, Linda L. Gregory, Glen H. Mittelhauser, Sally C. Rooney, and Jill E. Weber, published in the spring 2005 issue (vol. 107, No. 930) of Rhodora: Journal of the New England Botanical Club.