| Family: | Asteraceae; Compositae |
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| Common name: | sunflower family [Zomlefer, pp. 203-211] |
| Diversity: | Worldwide: 1,100 genera; 19,000 species U.S.: >200 genera PNW (Hitchcock & Cronquist): 104 genera |
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subdivided into 2 subfamilies and 12 to 17 tribes |
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| Flower | |
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Kx Co(5) S.GIF) or 0 P.GIF) or 0 |
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| Sexuality: | bisexual or unisexual |
| Symmetry: | actinomorphic and zygomorphic |
| Inflorescence: | flowers (florets) in a head (=capitulum); heads in racemes, panicles, corymbs or compound heads |
| Calyx (sepals): | rudimentary or absent (called a pappus) |
| Corolla (petals): | 5, united petals forming a tube. actinomorphic in "disc/tube" florets, often with five lobes at their tips; zygomorphic in "ray/ligulate" florets |
| Androecium: | 5 stamens, united by their anthers forming a tube around the style |
| Gynoecium: | 2 united carpels, inferior ovary (=epigynous), single style with two stigmatic lobes, single ovule |
| Fruit: | achenes or cypsela (=achene with attached calyx) |
| Other features: | head is composed of tiny florets, surrounded below by 1 to several series (=involucre) of protective bracts
some heads with bisexual, ray florets only; some heads with bisexual, tube florets only; some heads with outer ray and central tube florets derived breeding systems include dioecy, monoecy (ray=female/disc=male) and gynomonoecy (ray=female/disc=bisexual) |
| Vegetative Features | |
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| watery or milky sap | |
| Leaves: | usu. alternate, rarely whorled, often basal rosette, simple, rarely compound, exstipulate |
| Life-history: | annual to perennial |
| Habit: | mostly herbs and shrubs or trees |
| Distribution & Ecology: | cosmopolitan infrequent in tropical rain forest |
| Some Northwest Genera: | Antennaria, pussytoes Arnica, arnica Artemesia, wormwood, sagebrush Aster. aster Balsamorhiza, balsam root Centaurea, knapweed Cirsium, thistle Crepis, hawksbeard Erigeron, fleabane Haplopappus, goldenweed Helianthus, sunflower Hieracium, hawkweed Madia, tarweed Microseris, microseris Senecio, ragwort Solidago, goldenrod |
| Economic Importance | |
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| Crops: | Carthamus, safflower oil Lactuca lettuce Cynara, artichoke Helianthus, sunflower |
| Ornamentals: | many garden ornamentals (e.g.Chrysanthemum, Dahlia, and Zinnia) |
| Weedy and pest species: | Taraxacum, dandelion Cirsium, thistle Senecio jacobaea, tansy ragwort Xantium, cocklebur Ambrosia, ragweed (hayfever contributor) |
| Examples | Compositae Balsamorhiza |
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| Compositae Centaurea |
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| Compositae Cichorium |
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| Compositae Cirsium |
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| Compositae Taraxacum |
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| click on the genus name for a flower image | |
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