Sterculiaceae (sterculia family) and Tiliaceae (basswood family)- Introduction

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STERCULIACEAE
(Sterculia family)

Theobroma cacao


These are generally shrubs and trees with stellate hair. They are represented by about 60 genera and 700 species. Sterculiaceae are distributed exclusively in tropical and subtropical parts of the world. About 18 genera and 90 species have been reported from India. 
Some selected Indian genera are- 
    • Abroma, 
    • Helicteres, 
    • Sterculia, 
    • Theobroma, 
    • Pterospermum, 
    • Melochia.

ECONOMIC IMPORTANCE

    1. Chocolate, cocoa and cocoa butter are made from the seeds of Theobroma cacao which is rich in alkaloids thein and theobromine.
    2. Soft drinks are prepared from the cola nuts (Cola acuminata) which contain thein and caffeine.
    3. Fruits of Guazuma and seeds of Sterculia are edible whereas valuable fibres are obtained from the bark of Sterculia urns, S.villosa, Helicteres isora and Guazuma ulmifolia. 
    4. Wood of Heritiera minor is utilised for domestic purposes.
    5. Flowers of Pterospermum acerifolium are used as disinfectant and insect-repellant.
    6. Ornamental plants of Sterculiaceae grown usually in gardens, include species of Aroma, Brachychiton, Dombeya, Firmiana, Guazuma, Pentapetes, Pterospermum and Reevesia.
    7. Useful timber utilised for toys, match-sticks, Rea boxes etc. is obtained from species of Eriolaena cancelled, Heritiera littorals, Pterospermum diversifolium, Sterculia foetida and S. villosa.
    8. Gum of commercial importance is obtained from several species of Sterculia.
    9. Diabetes is cured by the juice of the roots of Helicteres isora whereas roasted seeds of Guazuma ulmifolia are used in stomach troubles. Fruits and seeds of Sterculia balanghas have laxative properties. 





TILIACEAE 
(Lime family or Basswood family)


Jute

Tiliaceae includes about 50 genera and 550 species of usually woody trees and shrubs with strong phloem fibres and rarely herbs (species of Triumfetta, Corchorus) or climbers (Plagiopteron). They are distributed in tropical and temperate regions, mainly in South East Asia and Brazil. About 15 genera and 100 species are found in India. 
Some selected Indian genera are: 
    • Tilia, 
    • Corchorus capsularis (jute), 
    • Triumfetta, 
    • Grewia subinaequalis (Phalsa), 
    • Elaeocarpus ganitrus (rudraksh) and 
    • Sparmannia.

ECONOMIC IMPORTANCE

    • JUTE-                                                                                                                             Two species of Corchorus (C. capsularis and C. olitorius) Are grown widely in warm areas as the source of jute fibres. Jute is obtained from the bast or phloem fibres. It is cultivated extensively in Bangladesh and West Bengal in India.
    • TIMBER-                                                                                                                   Several Tilia species are grown for their timber in temperate regions. Species of Berrya, Grew, Elaeocarpus and Erinocarpus are also grown for similar purposes.
    • ORNAMENTALS-                                                                                                     Several Tiliaceae are planted for ornamental value in parks, large gardens and on roadsides because of their fragrant flowers. Common among them are: 
    • Sparmannia africana (House lime), 
    • Tilia americana (Basswood), 
    • T. europaea (European linden), 
    • T. tomentosa (white linden), 
    • Grewia elastica, 
    • G. serrulata, 
    • Elaeocarpus ganitrus and 
    • Muntingia calabra. 
    • EDIBLES-                                                                                                                    Fruits of Grewia asiatiaca syn. G. subinaequalis (phalsa), G. genau, g. tilifolia and G. villosa are edible.
    • MEDICINAL VALUE-                                                                                                 
    • Dried leaves and decoction of roots of Corchorus capsularis and C. olitorius are used to cure dysentry and diarrhoea; 
    • Root bark of Grewia asiatica proves effective in rheumatism while its fruits help in digestion; 
    • G. microcos plants are used in eczema; 
    • Roots of G. sclerophylla are prescribed in cough; 
    • Wood of G. tiliaefolia is emetic and taken as an antidote to opium poisoning; 
    • Roots of G. villosa are used in diarrhoea; 
    • Leaves, flowers and fruits of Triumfetta bartramia are used against gonorrhoea.
    • FODDER-                                                                                                                      Leaves of Grewia glabra, G.oppositifolia, G. sapida and G. tenax are used as fodder for cattle.



Jute 
(extraction of fibre)






RETTING

Retting is a process by which the fibres in the bark get loosened and separated from the woody stalk due to removal of pectins, gums and other mucilaginous substances. This is usually effected by the combined action of water and microorganisms.
                                                                           The tied bundles of jute stems are taken to the nearest pool and laid flat in water at least 0.6-0.9 m in depth, and arranged side by side to form a regular platform, which is usually known as jak. The retting process is completed in 8-30 days. Fibre is extracted from the stalks of retted jute by hand or by decorticates. Retting is also done by chemical process.

Structure of Jute Fibre- The fibre in jute is a bast fibre obtained from the stem (secondary phloem). The fibre cells are longer in length and considerably lignified, and the fibre bears a silky lustre. 
            The longest fibre cells occur in the stems of the longest internodes. In general, the fibre cells of jute are much shorter than those of hemp, flax or cotton. Since the fibres are short, spinning by ordinary methods becomes difficult, and hence the use of jute fibres is limited to coarse fibres only.

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