In this article we will discuss about:- 1. General Characters of Malvaceae 2. Floral Formula of Malvaceae 3. Number and Distribution 4. Common Plants 5. Affinity and Economic Importance.
General Characters of Malvaceae:
Plants—usually herbs or shrubs, often mucilaginous and with stellate hairs on young parts. Leaves—alternate, simple, entire or variously lobed, mostly palmately veined, stipulate (free-lateral stripules). Inflorescence—cymose. Flowers—regular, bisexual (unisexual in Napaca), hypogynous, often showy, cyclic.
Sepals—5, more or less united, often subtended by an epicalyx (excepting Sida, Abutilon, etc.), valvate. Petals—5, free from one another but adnate at the base to the staminal tube, twisted. Stamens—numerous, usually monadelphous, with reniform, 1-celled anthers; pollen grains large and spiny.
Carpels—(1 to numerous); ovary—1-many-celled, but often 5-celled, with 1-many anatropous ovules in each cell and placed at the bottom of the staminal tube; style 1; stigmas as many or twice as many as carpels. Fruit— capsule or schizocarp, sometimes berry (e.g., Malvaviscus). Seeds—reniform, naked or comose with curved embryo and folded cotyledons.
Floral Formula of Malvaceae:
Number and Distribution of Malvaceae:
This family consists of about 82 genera and 1,500 species which are cosmopolitan excepting in very cold regions.
Range of Floral Structures in Malvaceae:
This family does not show wide variation in floral structure. Epicalyx is present in Malva, Hibiscus, Althaea and Lavetere, but absent in Sida and Abutilon. There are 3 epicalyces in Gossypium.
Variation in the number of carpels also occurs. Its number ranges from one to many. The number of carpels in Abutilon is 15-20; in Malva numerous; in Malvastrum 8-10 carpels; in Plagianthus 2 or 1; in Malope trifida numerous carpels are vertically arranged.
Styles as many as carpels, e.g., Abutilon, Sida, Malva, and Althaea; but twice as many as carpels in Pavonia, Kydia, Urena, and Malachra.
Stigma is spreading in Hibiscus and kydia, but connate into a club-shaped mass in Thespesia; ovary 3-celled in Kydia, but 5-celled in Hibiscus.
The position and number of ovules in the ovarian chamber also varies. Generally, the ovules are ascending but may be pendulous or horizontal; 2-ovuled ovary-chamber is found in Abutilon, but 1-ovuled ovary-chamber occurs in Sida and Malachra.
Common Plants of Malvaceae:
(1) Cotton-plant (Gossypium herbaceum L.), a shrub commonly cultivated for cotton.
(2) China-rose (Hibiscus rosa-sinensis L.), a common ornamental shrub.
(3) Lady’s-finger (Hibiscus esculentus.L. = Abelmoschus esculentus Moench.), cultivated throughout India for its fruit which is a vegetable; Roselle (H. sabdariffa L.), commonly cultivated for its fleshy calyx which is used in making pickles and jelly.
(4) Changeable rose (Hibiscus mutabilis L.), often planted in gardens for the sake of flower, the petals of which change from white to red in the course of a day.
(5) Deccan hemp (Hibiscus cannabinus L.), commonly cultivated for fibres.
(6) Urena lobata L. and U. sinuata L. are common weeds found everywhere.
(7) Indian mallow (Abutilon indicum Don.), commonly found in bushes; A. hirtum G. Don., an erect woody herb.
(8) Different species of Sida, e.g., S. cordifolia L., S. acuta Burm., S. rhombifolia L., S. rhombidea Roxb., and S. humilis Willd. = S. veronicaefolia L. are common weeds on waste places and roadsides.
(9) Portia tree or Tulip tree (Thespesia populnea Corr. = Hibiscus populneus L.), often planted as an avenue tree.
(10) Malachra capitata L., a common weed of waste places.
(11) Tree mallow (Hibiscus tiliaceous L.), a small tree found in Sundribans and also along river banks as far north as Calcutta.
(12) Malvastrum tricuspidatum Gray = M. coromandelianum Garcke, found in hedges and waste places.
(13) Pavonia odorata Willd., a weed of fields and waste places.
(14) Kydia calycina Roxb., a tree.
(15) Malva verticillata L., a very common plant.
(16) Hollyhock (Althaea rosea L.), a common garden plant.
Affinity and Economic Importance of Malvaceae:
This family is closely allied to Tiliaceae, Bombacaceae and Sterculiaceae in its general characters and aestivation of calyx but readily distinguished by monadelphous stamens, 1-celled anthers, large, spiny pollen grains, twisted corolla and presence of epicalyx.
Economic Importance of Malvaceae:
Malvaceae is of great economic importance. Gossypium is the most important plant which produces cotton of commerce; oil is extracted from the seeds for burning lamps and the oil-cake may be used as a fodder. Hibiscus cannabinus yields good fibres. Fruits of lady’s-finger (Abelmoschus esculentus) are used as vegetable. Hibiscus, Althaea, Malva, Malvaviscus, Thespesia, Callirhoe, etc., are ornamentals.
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