Characteristics and economic importance of family Malvaceae (Mallow Family)

May 28, 2018

1.Diagnostic Features

Mostly annual or perennial herbs, sometimes shrubs (Hibiscus rosa-sinensis) or trees.
Stem possesses mucilage and stellate hairs.
Leaves alternate and stipulate (stipules often deciduous).
Epicalyx usually present.

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Flowers actinomorphic, bisexual and hypogynous.
Stamens numerous monadelphous and epipetalous, anthers monothecous and reniform.
Ovary multicarpellary, syncarpous with axile placentation.
Fruit a capsule or schizocarp.

2. Distribution

They are widely distributed in tropical, sub-tropical, and temperate regions of the world.
The plants are less common in colder regions.

3. Vegetative characters

Habit: mostly annual (Althaea, Malva) or perennial herbs; shrubs or trees (Thespesia populnea). Grow both as wild and cultivated plants. Mucilagenous sap present in all parts.
Root: well branched tap root system.
Stem: erect, herbaceous or woody, branched, cylindrical or ribbed. Stellate hairs are often found on the stem.
Leaf: cauline and ramal, simple, alternate, petiolate, stipulate. Margin entire or variously lobed, venation multicostate, reticulate.

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4. Floral characters

Inflorescence: usually solitary axillary (Thespesia) or terminal (Malvastrum), sometimes racemes (Hibiscus) or cymose panicles (Malva, Althaea).
Flower: pedicellate, bracteates, complete, bisexual, rarely unisexual (Napaea), actinomorphic, hypogynous, pentamerous, variously coloured. A whorl of epicalyx is present.
Epicalyx: outside the calyx, a whorl of 5-8 in-volucral bracts is often present. It might be absent (Sida, Abutilon).
Calyx: sepals 5, gamo-sepalous or free persistent, green, aestivation valvate.
Corolla: petals 5, polypetalous, adnate at the base with the stamina tube, aestivation twisted or imbricate.
Androecium: stamens numerous, monadelphous forming a staminal tube around the ovary and the style, epipetalous, anthers monothecous, reniform, basifixed, extrose, dehiscence by longitudinal slits.
Gynoecium: carpels 1 to many, syncarpous, usually pentacarpellary, rarely 3 in Kydia, 1 0r 2 in Plagianthus, 10 in Hollyhock. Ovary superior, multilocular, eith 1-many ovules in each locule, placentation axile. Style long, stigmas are as many or doublethe number of carpels, simple discoid or capitate.
Fruit: usually a capsule (Gossypium), or schizocarpic (Malva), sometimes a berry (Malvaviscus), or a samara.
Seeds: embryo straight or curved, endosperm scanty.
General floral formula:

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Economic importance

Cotton: most important product, manufactured from dense mass of fibres attached to the seeds of several species of Gossypium.
Bags, ropes, cords, etc are made from the bast fibres obtained from Abutilon asiaticum, Hibiscus falcatus, etc.
Edible oil is prepared from the seeds of cotton. It is used for manufacture of soap, lubricants, etc. the oil cake is used as excellent cattle feed.
Vegetables: the fruit of lady’s finger (Hibiscus esculentus– Bhindi) and the leaves of Hibiscus cannabinus are used as vegetable.
Ornamentals: has ornamental value like Hibiscus rosa- sinensis (China rose or shoe flower), H. mutabilis (cotton rose), etc.
Medicinal value: Gossypol obtained fom cotton seed and oil is used as natural male antifertilty chemical. Roots and barks of Urena rapanda are used to cure hydrophobia, roots of Althaea are used in the treatment of dysentery.

References:

I am Shailesh Koirala