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In this article we will discuss about:- 1. Characters of Sterculaceae 2. Distribution of Sterculaceae 3. Economic Importance 4. Affinities.
Characters of Sterculaceae:
Plants herbs or trees with stellate hairs; fibrous stem and mucilage sacs; leaves alternate, stipulate; flower regular, hypogynous, hermaphrodite rarely unisexual; sepals and petals 5 each; stamen in two whorls, outer staminodes, inner united into a tube, fertile stamens alternated with staminodes, monadelphous stamens bithecous; carpels 5, syncarpous, ovary pentalocular, axile placentation, sometimes raised on andro-gynophere; fruit schizocarpic.
A. Vegetative characters:
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Habit:
Trees, shrubs and a few herbs-with stellate hairs, rarely climber (Ayenia).
Root:
Tap, branched.
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Stem:
Erect, branched, fibrous wood and with mucilage sacs.
Leaf:
Simple or palmately compound or lobed or with entire margins, alternate, stipulate, stipule caducous.
B. Floral characters:
Inflorescence:
Paniclecl cyme or cymes or in clusters.
Flower:
Actionomoprhic, hypogynous, hermaphrodite or unisexual by abortion of one of the members of essential whorl; pentamerous.
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Calyx:
Sepals 3-5, valvate, basally connate.
Corolla:
Petals 5 or none (Sterculia, Heritiera), free, imbricate, corolla turned either to left or right, petals sometimes adnate to the stamined column.
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Androecium:
Stamens in two whorls, those of outer whorl are antisepalous and reduced to staminodes, scales or absent, those of inner whorl antipetalous, definite or indefinite, and monadelphous, anthers bithecous.
Gynoecium:
Capels 3-5, syncarpous, ovary superior, pentalocular or multilocular sometimes raised above by the development of gynophore, axile placentation. each chamber with 2 to many ovules.
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Fruit:
Usually schizocarpic capsule or typical capsule, indehiscent or dehiscent, sometimes splitting into cocci.
Seed:
Numerous, with fleshy endosperm, often winged, arillate.
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Pollination:
Entomophilous.
Floral formula:
Distribution of Sterculaceae:
The Cocoa family comprises about 50 genera and 750 species, largely confined to the tropics and subtropics.
Economic Importance of Sterculaceae:
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1. Food:
The seeds of Theobroma cacao on grinding yield cocoa and chocolate. The seeds are first fermented and then roasted before grinding. Fruits of Gauzuma ulmifolia and seeds of Sterculia are edible.
2. Medicinal:
The root-bark or roots of Abroma augusta are menagogue (used in female diseases).
Cola nuts obtained from Cola vera and Cola accuminata contain Caffein and thein; when chewed they help to overcome fatigue. They are also used in some refreshing drinks.
3. Insect repellent:
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Flowers of Pterospermum are very good insect repellants and disin fectants.
4. Wood:
It is obtained from Heritiera, Sterculia species. Mansonia dipikae yields timber.
5. Ornamentals:
Abroma, Dombeya, Pentapetes, Pterospermum acerifolium etc. are often planted as ornamentals.
Affinities of Sterculaceae:
The family Sterculiaceae bears remarkable affinity with Euphorbiaceae in the following morphological characters such as stellate hairs, nature of fruit, occasional presence of androphore, tendency of unisexality, presence of caruncle in the seeds of some genera {e.g. in Sterculia) and leafy cotyledons.
Bentham and Hooker placed the family with other allied families such as Malvaceae, Tiliaceae under Thalamiflorae after Dipterocarpeae. Engler put the family in his. 29th series Marvales preceding Parietales. According to Rendle this family falls under Malvales or Columniflorae after Guttiferales and before Tricoceae. Hutchinson too placed the family in this series Tilio-Malvales near Euphorbiales.
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Common plants of the family:
1. Abroma augusta L. – Devili’s cotton or Perennial Indian hemp. — a good substitute of hemp.
2. Dombeya mastersii – Ornmental plant of gardens.
3. Helicteres isora L. – East Indian Screw Tree, common in Sunderbans.
4. Pterospermum acerifolium – Avenue tree, flowers vary fragerent.
5. Sterculia foetida – Jangali badam; an avenue tree.
Division of the family and chief genera:
Tribe I. Lasiopetaleae:
Calyx petaloid, petals O or small, scale-like. Stamens slightly connate at the base, 5, perfect, Staminodes O; fruit capsule. Genera : Seringia, Guichenotia.
Tribe II. Sterculae:
Flowers unisexual, calyx petaloid; petals O. stamens 5-indefinite, monadelphous. Mature fruit separating into carpellary parts. Genara : Sterculia, Heritiera.
Tribe III. Hermannieae:
Flowers Bisexual, petals more or less persistent. Stamens 5, opposite to petals, monadelphous. Ovary 1-5 loculer. Fruit capsule. Genera : Melochia, Waltheria.
Tribe IV : Dombeyeae:
Flowers bisexual; petals persistent. Stamens indefinite with steminodes, monadelphous, staminal column cupular, Ovary 5 or more celled. Fruit capsule. Genera : Dombeya, Pentapetes etc.
