Answer
Answer
Immense structural diversity exists in this family of some 20,000 species. Members of this family are easily identified by recognizing the composite flowerlike inflorescence known as the involucrate pseudoanthium. Multiple florets emerge from a common receptacle to form a radiate, discoid, or ligulate head or capitulum (see below). These complicated flower heads are surrounded by 1 or more rows of bracts, which are most often green.
Daisy flower, Leucanthemum species, with characteristic flower heads of the Asteraceae family.
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Media Gallery
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Young poison ivy plant Toxicodendron radicans. The leaves of 3 are easily identified. Reprinted with permission from WB Saunders.
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Mature poison ivy Toxicodendron radicans. Fruit arises in an axillary position in the angle between the leaf and the branch.
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Mature gingko tree, Ginkgo biloba, growing in Frederick, Md.
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Ginkgo biloba has a characteristic bilobed leaf.
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Daisy flower, Leucanthemum species, with characteristic flower heads of the Asteraceae family.
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Finger of a florist with an eczematous plaque caused by sensitivity to tulipalin A, the allergen contained in Peruvian lilies (family Alstroemeria).
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Airborne contact dermatitis in a patient who is allergic to sesquiterpene lactones. The involvement of the anterior part of the neck seen here is typically absent in photodermatoses. Courtesy of Dirk Elston, MD.
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Irritant reaction on the scrotum after contact with garlic (Allium sativum). Courtesy of Martin Giandoni, MD. Reprinted with permission from Cutis 67: 193, 2001.
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Tulipa species (Liliaceae). Reprinted with permission from Cutis (2003;71:347-348). Copyright 2003, Quadrant HealthCom, Inc.
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The coverings of tulip bulbs can cause irritant contact dermatitis, and tulipalin A and B can cause allergic contact dermatitis. Reprinted with permission from Cutis (2003;71:347-348). Copyright 2003, Quadrant HealthCom, Inc.
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Alstroemeria ligtu (Alstroemeriaceae). Reprinted with permission from WB Saunders.
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Primula obconica
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Urtica dioica, the common stinging nettle.
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Prickly pears, Opuntia species.
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Dieffenbachia bauseii (Araceae), also known as dumb cane.
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Daffodils, Narcissus pseudonarcissus, are also known as Lent lilies because they bloom in late March and early April in much of the United States.
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Chili peppers, Capsicum annum.
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