Asteraceae (Compositae)

(Sunflower Family)

Habit

herbs, shrubs (trees)

Leaves

opposite, alternate, whorled, simple, very rarely compound

Inflorescence

capitulate (capitulum); involucral bracts = phyllaries; receptacular bracts = chaff

Flowers

perfect, imperfect (pistillate, staminate, neuter)

Sepals

calyx modified into pappus (awns, scales, or capillary bristles plumose)

Petals

corolla tube & limb; limb comprised of the throat and corolla lobes

Stamens

anthers: connate or connivent into a tube, pollen shed to inside and removed by style as it elongates; filaments most often free from each other, but attached to the corolla

Ovary

of 2 fused carpels; inferior with 1 locule, 1 basal ovule

Style

2 branches

Fruit

achene

Diversity

second largest family of flowering plants: 13 tribes (traditional); circa 1100 genera, circa 20-22,000 spp. (if you consider all those orchids to be species).

Distribution

cosmopolitan, found in temperate, subtropic and tropical areas

Economics

mostly ornamentals; numerous weeds; lettuce, oil from sunflower,..

Floret types

ray florets: often pistillate or occasionally neuter; usually only three teeth at apex with two vestigial teeth near base of throat
ligulate florets: perfect; all five teeth at apex
disk florets: most often perfect, regular
filiform florets: ligule vestigial or lacking; pistillate
naked florets: lack corolla; pistillate [rare]

Head types

radiate heads: ray florets and disc florets
ligulate heads: ligulate florets (diagnostic of the tribe Lactuceae)
discoid heads: only disc florets
disciform heads: filiform and disc florets mixed

MAJOR TRIBES of ASTERACEAE in NORTHERN ARIZONA Lactuceae (Lettuce tribe) cosmopolitan distribution; 75 genera 1550 spp. distinctive features: ligulate flowers, milky sap. Including: Lactuca (lettuce), Cichorium (endive), Taraxacum (dandelion), Sonchus (local weed), Tragopogon (salsify)... Cardueae (Thistle tribe) Eurasian (some North and South American distribution); 78 genera, 2500 spp. distinctive features: spiny leaves and/or spine-tipped involucral bracts; receptacle has numerous bristles; heads discoid, but often the outer florets are expanded and zygomorphic (occasionally pistillate or neuter); anthers tailed and style with expanded, hairy area below the branches. Incl. Cirsium (thistles), Carduus (occ. weed locally in bar ditches), Carthamus (oil, dye), Cynara (artichoke), Centaurea (Russian thistle and related species), Echinops (Globe thistle of cultivation) Heliantheae (Sunflower tribe) mostly New World and Northern Hemisphere; center of diversity in Southwest US; ca. 260 genera, 3000 spp. Extremely diverse group usually with chaffy receptacle, pappus of awns or scales and usu. yellow radiate heads (sunflowers) or discoid heads with white flowers (Pericome) or discoid (single-flowered) heads and wind-pollinated (Ambrosia --hayfever); achenes with carbonized wall of phytomelanins (Eups, also); Including Helianthus (Sunflower), Dahlia, Coreopsis, Gaillardia, Ambrosia (hay fever), Bidens (beggars ticks), Rudbeckia, Zinnia... Astereae (Aster tribe) temperate areas of the New World and south Africa; 143 genera, ca. 2500 spp. distinctive features: radiate, disc or disciform heads, relatively small, disc usually yellow-flowered, but rays blue, yellow, white, purple; receptacle not usually chaffy, style branches with subulate or triangular appendages; pappus usu. of capillary bristles. Incl. Aster, Erigeron, Baccharis, Conyza, Grindelia, Haplopappus, Machaeranthera, & Solidago (all local) Senecioneae cosmop. distr., 97 genera, ca. 3000 spp. distinctive features: heads radiate, discoid or disciform, single row of more or less equal involucral bracts (picket fence) with occ. much shorter rank of phyllaries; flowers mostly yellow, rays pistillate and fertile, disk flowers perfect; pappus of capillary bristles; receptacle naked. Senecio (ca. 1500 spp., some poisonus weeds); considered to be the oldest tribe in family on the basis of his Willis' Age and Area Hypothesis. Anthemideae mostly temperate regions of Northern Hemisphere; 102 genera, 1400 spp. distinctive features: strongly scented, dissected or compound leaves; heads radiate or discoid (disciform), involucral bracts scarious margined... Incl. Artemisia (sage, absinthe, & tarragon) and other culinary herbs, Chamaemelum (camomile), Tanacetum (incl. pyrethrum), Chrysanthemum (cultivated ornamental) and Achillea (yarrow).

Images ">Vascular Plant Image Gallery (Texas A&M Bioinformatics Working Group) Wisconsin State Herbarium ">Google Images

footer

Tina Ayers	Meredith Jabis	Schedule	Syllabus	Web Resources	Webmaster

Lactuceae (Lettuce tribe) cosmopolitan distribution; 75 genera 1550 spp. distinctive features: ligulate flowers, milky sap. Including: Lactuca (lettuce), Cichorium (endive), Taraxacum (dandelion), Sonchus (local weed), Tragopogon (salsify)...
		Cardueae (Thistle tribe) Eurasian (some North and South American distribution); 78 genera, 2500 spp. distinctive features: spiny leaves and/or spine-tipped involucral bracts; receptacle has numerous bristles; heads discoid, but often the outer florets are expanded and zygomorphic (occasionally pistillate or neuter); anthers tailed and style with expanded, hairy area below the branches. Incl. Cirsium (thistles), Carduus (occ. weed locally in bar ditches), Carthamus (oil, dye), Cynara (artichoke), Centaurea (Russian thistle and related species), Echinops (Globe thistle of cultivation)
Heliantheae (Sunflower tribe) mostly New World and Northern Hemisphere; center of diversity in Southwest US; ca. 260 genera, 3000 spp. Extremely diverse group usually with chaffy receptacle, pappus of awns or scales and usu. yellow radiate heads (sunflowers) or discoid heads with white flowers (Pericome) or discoid (single-flowered) heads and wind-pollinated (Ambrosia --hayfever); achenes with carbonized wall of phytomelanins (Eups, also); Including Helianthus (Sunflower), Dahlia, Coreopsis, Gaillardia, Ambrosia (hay fever), Bidens (beggars ticks), Rudbeckia, Zinnia...
		Astereae (Aster tribe) temperate areas of the New World and south Africa; 143 genera, ca. 2500 spp. distinctive features: radiate, disc or disciform heads, relatively small, disc usually yellow-flowered, but rays blue, yellow, white, purple; receptacle not usually chaffy, style branches with subulate or triangular appendages; pappus usu. of capillary bristles. Incl. Aster, Erigeron, Baccharis, Conyza, Grindelia, Haplopappus, Machaeranthera, & Solidago (all local)
Senecioneae cosmop. distr., 97 genera, ca. 3000 spp. distinctive features: heads radiate, discoid or disciform, single row of more or less equal involucral bracts (picket fence) with occ. much shorter rank of phyllaries; flowers mostly yellow, rays pistillate and fertile, disk flowers perfect; pappus of capillary bristles; receptacle naked. Senecio (ca. 1500 spp., some poisonus weeds); considered to be the oldest tribe in family on the basis of his Willis' Age and Area Hypothesis.
		Anthemideae mostly temperate regions of Northern Hemisphere; 102 genera, 1400 spp. distinctive features: strongly scented, dissected or compound leaves; heads radiate or discoid (disciform), involucral bracts scarious margined... Incl. Artemisia (sage, absinthe, & tarragon) and other culinary herbs, Chamaemelum (camomile), Tanacetum (incl. pyrethrum), Chrysanthemum (cultivated ornamental) and Achillea (yarrow).