ASTERACEAE

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            1. SYSTEMATIC POSITION:
            Bentham & Hooker
            Division: Phanerogames (Seed Plants)
                 Class: Dicotyledones
                       Sub-class: Gamopetalae
                             Series: Inferae
                                   Order: Asterales
                                         Family: Asteraceae
           
            2. MORPHOLOGICAL CHARACTERS:
            Habit – Herbs or shrubs, rarely trees, aromatic.
            Leaves – Alternate or opposite, simple, exstipulate.
            Inflorescence – Head, surrounded by an involucres bract.
            Flower – Actinomorphic when tubular, zygomorphic when ligulate, or both when forming disc and ray florets, unisexual or bisexual, epigynous.
            Calyx – Reduced or modified into hair like structure called pappus.
            Corolla – Petals 4 or 5, united, imbricate.
            Androecium – Stamens 4 or 5, epipetalous, syngenesious, anthers bithecous, connective prolonged upwards.
            Gynoecium – Carpel 2, syncarpous, ovary inferior, unilocular with a basal ovule, style bifid at the top, and recurved.
            Fruit – Cypsela, crowned with or without persistent pappus.
              4. COMPARATIVE SYSTEMATIC POSITION AND AFFINITIES:
            Bentham & Hooker placed this family along with other three families under the orderAsterales. Engler & Prantl placed the family Asteraceae in the order Campanulatae. Hutchinson put this family in the monotypic order Asterales.
            All taxonomists are in agreement that the Asteraceae is the most advanced family among dicotyledones. The family is considered to be one of the most highly evolved and successful families of the angiosperms in the presence of involucrate head, gamopetalous corolla, inferior ovary with a single basal ovule, syngenesious stamens and non endospermic seeds with pappus which help them for their dissemination.
            In possessing pentamerous flowers, syngenesious stamens and inferior ovary, Asteraceae is related to Campanulaceae and Goodeniaceae. In possessing inferior bilocular ovary, this family is allied to to Rubiaceae and Stylidiaceae. It is presumed that Asteraceae originated from Rubiaceae.
                 5. ECONOMIC IMPORTANCE:
            1. The family possesses showy flowers which makes it ornamentally important. The ornamentally important plants are – Chrysanthemium coronarium, Dahlia pinnata, Helianthus annus, Cosmos bipinnatus, Zinna elegans, Z. panciflora, Calendula officinalis, Tagetes erecta, Echinops spp. etc.
            2. Medicinally important plants of the family are – Artemisia absinthium, A. maritime, Arnica montana, etc.
            3. Oil yielding plants are – Carthamus tinctorius, Guizotia abyssinica, Helianthus annus, Wedelia calendulacea, etc.
            4. Vegetable plants include – Lactuca sativa, Cichorium intybus, Helianthus tuberosus, Tragopogon porrifolium, etc.

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