In this article we will discuss about:- 1. General Features of the Tiliaceae 2. Floral Range in the Tiliaceae 3. Position and Affinity 4. Number and Distribution 6. Commonly Occurring Plants 7. Economic Aspects.
General Features of the Tiliaceae:
Habit:
Shrubs or trees, rarely herbs; inner bark fibrous; juice mucilaginous.
Leaves:
Alternate, simple, entire or toothed, stipulate or exstipulate.
Inflorescence:
Cymose
Flowers:
Bisexual or unisexual, regular.
Calyx:
Sepals 5, free or united.
Corolla:
Petals 5, free, imbricate.
Androecium:
Stamens many, inserted on a disc, free or polyadelphous; anthers, 2-celled.
Gynoecium:
Carpels 2-5, syncarpous; ovary superior, 2-locular to 10-locular with 1 or more ovules in each cell.
Fruit:
Capsule or drupe.
Seeds:
Albuminous; embryo curved with leafy cotyledons.
Floral Range in the Tiliaceae:
The flowers of the Tiliaceae are bisexual, but unisexual in Cardioptersa and Vasivaea.
Although pentamerous calyx and corolla are present in most of the flowers, Sparmannia is characterised by tetramery. The petals may be absent, as in Prockia and Solmsia.
The carpels indicate much variation. In Belotia, the placentation is basally axile and distally parietal. The ovary may remain unilocular and the placentation parietal, as in Goethalsia and Mollia. The ovary can also be initially unilocular with five to six deeply intruded placentae that tardily cohere or unite at the centre.
Divisions of the Tiliaceae:
The Tiliaceae is divided into four tribes:
Tribe (i) Apeibeae:
Sepals free. Anther lobes not confluent. Stamens with apical appendages; androphore absent. Carpels 6 to many. Examples: Ancistrocarpus, Apeiba, etc.
Tribe (ii) Brownloweae:
Sepals connate at base. Anther lobes confluent at apex. Examples: Berrya, Brownlowia, etc.
Tribe (iii) Greweae:
Petals with basal glands. Androphore present. Examples: Duboscia, Grewia, etc.
Tribe (iv) Tilieae:
Sepals connate at base. Stamens without appendages. Carpels 2-5. Example: Tilia.
Position and Affinity of the Tiliaceae:
Rendle included the Tiliaceae in his seventh order Malvales after the Guttiferales and before the Tricoccae. Hutchinson separated the Tiliaceae from the Malvales and placed it under the Tiliales.
The Tiliaceae is similar to the Sterculiaceae in habit, leaves and stipules. It is akin to the Elaeocarpaceae and hence the latter was incorporated by Bentham-Hooker into the Tiliaceae. Engler set the Elaeocarpaceae apart from the Tiliaceae due to the mucilage as well as the presence of imbricate sepals and porous dehiscence of anthers. The Tiliaceae is allied to some members of the Euphorbiaceae which has free stamens inserted upon a gynophore.
Number and Distribution of the Tiliaceae:
The family is composed of about 41 genera and 400 species. Although mostly found in the tropics, some plants of the Tiliaceae extend even to the temperate regions.
Commonly Occurring Plants of the Tiliaceae:
Berrya cordifolia (Willd.) Burret and Grewia tiliaefolia Vahl are tall trees, while G. elastica Royle and G. subinequalis DC. are small trees.
Brownlowia tersa (L.) Kosterm. is a small tree from Sunderbans.
Corchorus aestuans L. non Forsk. and Triumfetta rhomboidea Jacq. are weeds of waste places.
Corchorus capsularis L. and C. olitorius L. are important crop plants of India.
Elaeocarpus floribundus Bl. and E. sphaericus (Gaertn.) K. Schum. are found in North Bengal.
Muntigia calabura L. is a garden shrub.
Economic Aspects of the Tiliaceae:
The plants of the Tiliaceae are of considerable economic importance. The berries of Aristotelia macqui, Grewia elastica, G. subinequalis and G. tiliaefolia are edible. Berrya cordata, B. cordifolia, Erinocarpus nimmonii, Tilia americana and T. vulgaris yield timber. The leaves of Corchorus aestuans are good for stomach disorders. The stem bark of C. capsularis and C.olitorius produces the ‘jute’ of commerce.
The seeds of Elaeocarpus sphaericus are made into beds. Sparmannia africana (South Africa) is grown for its handsome clusters of white flowers.
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