11th Class Biology Families Malvaceae


Category : 11th Class

Systematic position

        Division      :         Angiospermae

        Class            :         Dicotyledonae

        Subclass     :         Polypetalae

        Series          :         Thalamiflorae

        Order          :         Malvales             

        Family         :         Malvaceae

Habit : Plants are annual herbs (e.g., Malva, Sida, Malvastrum, Urena) shrubs (e.g., Hibiscus rosa-sinensis, H. mutabilis) or rarely trees (e.g., Kydia, Bombax).

Root : Branched tap root system.

Stem : Stem is erect, aerial, herbaceous or woody, usually solid, cylindrical and branched. Herbaceous portion of the stem is covered with stellate and scaly hairs; the woody part is fibrous. Plants usually have some mucilaginous substance.

Leaves : Leaves are alternate and stipulate (stipules 2, free lateral and often Caducous). They are simple and petiolate, lamina is sometimes palmately lobed (e.g., Gossypium) or digitate (e.g., Bombax). Venation is multicostate reticulate.

Inflorescence : Usually the flowers are solitary axillary or terminal. Occasionally, they are in panicle raceme (e.g., Kydia).

Flowers : Flowers are bracteate or ebracteate, actinomorphic, bisexual (unisexual in Kydia), pentamerous and hypogynous. The number of bracteoles varies from 3 to many, they form a whorl of epicalyx below the calyx. Sometimes the epicalyx is absent (e.g., Sida and Abutilon).

Calyx : Sepals 5, gamosepalous (connate at the base but free at the tip) and show valvate aestivation. Usually epicalyx present.

Corolla : Petals 5, polypetalous (slightly fused at the base), usually adnate at the base to the staminal tube. They show twisted or imbricate aestivation.

Androecium : It has indefinite stamens. They are monadelphous. Filaments of the stamens are united to form a long staminal tube or staminal column which encloses the style. Basal part of the staminal tube is fused with the petals; thus stamens are epipetalous. Anthers are monothecous, reniform, transversely attached to the filament and extrorse. In Bombax stamens are polyadelphaous.

Gynoecium : It is 2 to many carpellary. It is bicarpellary in Plagianthus, tricarpellary in Kydia, pentacarpellary in Hibiscus and Sida, ten carpellary in Althaea rosea and 15 – 20 carpellary in Abutilon indicum. All the carpels are fused (syncarpous) to form a single ovary. Ovary is superior, multilocular with one or more ovules in each chamber. The placentation is axile.

Style is usually long and enclosed in the staminal tube. Stigmas are as many as the number of carpels or double the number of carpels.

Fruit : Fruit is a loculicidal capsule (e.g., Gossypium, Hibiscus), schizocarpic capsule (e.g., Abutilon, Sida) or a berry (e.g., Malvastrum).

Seed : Seeds are albuminous. In Gossypium the seeds are pubescent, i.e., covered with hairs.

Floral formula :

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