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In this article we will discuss about:- 1. Characters of Tiliaceae 2. Distribution of Tiliaceae 3. Affinities 4. Economic Importance 5. Important Types.
Characters of Tiliaceae:
Leaves simple, stipulate; flower hermaphrodite, hypogynous, actinomorphic, stamens indefinite sometimes 5 to 10; carpels 2 to indefinite, syncarpous, axile placentation; fruit capsule or drupe.
A. Vegetative characters:
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Habit:
Shrubs or trees rarely herbs (Corchorus) with mucilagenous juice.
Root:
Tap and branched.
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Stem:
Erect, cylindrical or angular, woody, solid and branched.
Leaves:
Alternate rarely opposite, simple, margin entire, dentate or lobed-, stipulate, stipule caducous (Tilia).
B. Floral characters:
Inflorescence:
Cymose and often very complex (Tilia, Triumfetta).
Flower:
Pedicellate, actinomorphic, hypogynous, hermaphrodite, rarely unisexual (Carpodiptera), tetra or pentamerous, sometimes with epicalyx.
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Calyx:
Sepals 5 or 4 rarely 3, polysepalous or basally connate, valvate aestivation, inferior.
Corolla:
Petals 5 or 4 rarely absent (Prockia), polypetalous, often glandular, imbricate aestivation, usually coloured but sometimes sepaloid, inferior.
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Androecium:
Stamens 10 to indefinite, free or united in groups (Grewia), inserted at the base of petals or on androphore (Grewia), anthers dithecous, extrorse, dehiscence by apical pores or longitudinal slits.
Gynoecium:
Carpels 2 to 10 or many (Apeiba), syncarpous; ovary superior, 2 to many locular with 1 to many anatropous ovules in each loculus; axile placentation; style simple; stigma capitate or lobed.
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Fruit:
Capsule or schizocarpic or drupaceous.
Seed:
Endospermic, embryo curved with leafy cotyledon.
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Pollination:
Entomophilous.
Floral formula:
Distribution of Tiliaceae:
It is commonly called Jute family. It comprises 50 genera and 450 species. The members are mostly tropical and some inhabitants of temperate climate. It is abundant in South East Asia and Brazil.
Economic Importance of Tiliaceae:
1. Fibre:
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Corchorus capsularis and C. olitorius are cultivated for their tenacious blast fibres, which yield jute of commerce. It is used in making gunny bags.
2. Medicinal:
The fruits of Grewia asiatica are astringent, cooling and digestive. The root bark is used in rheumatism.
The flowers, leaves and fruits of Triumfetta bartramia are used in gonorrhoea. Bark and fresh leaves of this plant are used in diarrhoea and dysentery.
3. Wood:
The species of Tilia yield useful timber. Tilia americana is one of the best timber plant of America.
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4. Ornamental:
Some of the plants viz. Sparmannia, Microcos are grown in gardens.
Primitive characters:
1. Plant are generally shrubs or trees.
2. Leaves alternate, simple, stipulate.
3. Flowers hermaphrodite, hypogynous and actinomorphic.
4. Corolla polypetalous.
5. Gynoecium polycarpellary (Apeiba).
6. Seeds endospermic.
Advanced characters:
1. Inflorescence cymose or complex (Tilia).
2. Flowers unisexual (Carpodipetera).
3. Corolla rarely absent (Prockia).
4. Gynoecium syncarpous with axile placentation.
5. Presence of curved embryo in the seeds.
Affinities of Tiliaceae:
The family Tiliaceae is related to Sterculiaceae in habit, leaves, stipules and androphore (Grewia). It differs from Malvaceae in stellate hairs, dithecous anthers and polyadelphous stamens.
It is also allied to the family Elaeocarpaceae and hence Bentham and Hooker had included the latter in Tiliaceae. Engler has set the family Elaeocarpaceae apart from Tiliaceae due to mucilage, presence of imbricate sepals and porous dehiscence of anthers.
Common plants of the family:
1. Corchorus – The well known Jute fibre, is obtained from this plant.
2. Grewia asiatica – The fruits are acidic and syrups are made from it.
3. Telia – A big tree.
4. Triumfetta bartramia – A weed of waste places.
Division of family and chief genera:
The family Tiliaceae has been divided into four tribes:
Tribe (i) Tiliae:
Sepals connate at the base, stamens without appendages; carpels 2 to 5. Tilia.
(ii) Greweae:
Petals with basal glands; androphore present. Grewia, Duboscia.
(iii) Brownloweae:
Sepals connate at the base and free at the apex; anther-lobes confluent at apex. Brownlowia, Berrya.
(iv) Apeibeae:
Sepals free, anther-lobes free, stamens with apical appendages, androphore absent; carpels six to indefinite. Apeiba, Ancistrocarpus.
Important Type of Tiliaceae:
Corchorus capsularis (Fig. 40.1):
Habit:
Annual herb.
Root:
Tap and branched.
Stem:
Erect, branched, glabrous, woody and solid.
Leaves:
Simple, lanceolate, acute or acuminate apex, glabrous, serrate margin, base round or acute, petiolate, stipulate-stipule filiform.
Inflorescence:
Axillary.
Flower:
Pedicellate, actinomorphic, hermaphrodite, hypogynous, complete, pentamerous.
Calyx:
Sepals 5, sepaloid, polysepalous, valvate aestivation, inferior.
Corolla:
Petals 5, polypetalous, twisted aestivation, inferior.
Androecium:
Stamens indefinite, free, anthers dorsifixed, bithecous, introrse, inferior.
Gynoecium:
Pentacarpellary, syncarpous; ovary superior, pentalocular, axile placentation, two or more ovules per loculus; style simple; stigma simple.
Fruit:
Capsule, sub-globose ridged, not breaked.
Floral formula:
