In this article we will discuss about:- 1. General Features of the Sterculiaceae 2. Floral Range in the Sterculiaceae 3. Number and Distribution 4. Commonly Occurring Plants 5. Economic Aspects.
General Features of the Sterculiaceae:
Habit – Shrubs or trees, sometimes herbs with mucilage.
Leaves – Alternate, simple, entire or lobed or digitately compound, stipulate.
Inflorescence – Cymose.
Flowers – Bisexual, sometimes unisexual, regular or irregular, hypogynous.
Calyx – Sepals 3-5, somewhat partially united, valvate.
Corolla – Petals 5, occasionally 0, imbricate.
Androecium – Stamens many, free or monadelphous-, anthers 2-celled with intervening staminodes.
Gynoecium – Carpels 2-5; ovary syncarpous, often on a gynophore’, ovules few to many.
Fruit – Capsule or follicle.
Seeds – Arillate, often winged; embryo with flat, folded or rolled, leafy cotyledons; endosperm fleshy.
Floral Range in the Sterculiaceae:
The flowers are generally bisexual, but may be unisexual (Cola, Heritera, Sterculia, etc.). They are regular or irregular and pentamerous.
Frequently, the petals are reduced in size and sometimes absent. The stamens are in two whorls; those of the inner (antipetalous) are fertile and those of the outer (antisepalous) sterile. Many flowers show the presence of staminodes, but they are wanting in Eriolaena. Though the androgynophore is present in a number of plants, it is lacking in Helicteres, Mansonia and other genera.
Number and Distribution of the Sterculiaceae:
This is a pantropical and subtropical family of about 60 genera and 700 species.
Commonly Occurring Plants of the Sterculiaceae:
Devil’s Cotton or Perennial Indian Hemp [Abroma augustum (L.) L. f.] is a shrub.
Buettneria herbacea Roxb. is a herb.
Dombeya mastersii Hook. f. is a garden shrub.
Firmiana colorata (Roxb.) R. Br., Kleinhovia hospita L., Pterygota alata (Roxb.) R. Br. and Sterculia foetida L. are trees planted on road sides.
Bastard Cedar (Guazuma ulmifolia Lamk.) is a middle sized tree with woody tubercled globose capsule.
East Indian Screw Tree (Helicteres isora L.) is a shrub, the follicles of which on dehiscing twist spirally and expel the seeds.
Heritera fames Buch-Ham. is a tree from which the Sunderbans takes its name.
Melhamia magnifolici Blatt. & Hallb. occurs in Rajasthan.
Melochia corchorifolia L. and Waltheria indica L. are weeds of waste places.
Noon Flower (Pentapetes phoenicia L.) is a garden plant with scarlet flowers.
Pterospermum acerifolium Willd. is an avenue tree with white odorous bisexual flowers and long fleshy sepals.
Economic Aspects of the Sterculiaceae:
The plants of the Sterculiaceae are valuable for a number of purposes. The species of Abroma, Bracychiton, Dombeya, Firmiana, Fremonodendron, Pterospermum and Reevesia are cultivated as ornamentals. The root-bark of Abroma augustum has curative properties in female diseases. Cola acuminata (tropical America) is the source of cola nuts, producing ‘caffeine’, which when consumed, confers the power to endure fatigue and thus find application in the manufacture of soft drinks.
The bark of Guazuma ulmifolia, Helicteres isora, Sterculia urens and S. villosa yield fibres. Heritera fames provides us with the best firewood as well as wood for heavy construction. Mansonia dipikae yields timber. The flowers of Pterospermum acerifolium find uses as an insect repellant and as a disinfectant. From the seeds of Theobroma, cacao, yielding the alkaloids ‘thein’ and ‘theobromin’ and widely cultivated in South India and Sri Lanka, we get chocolate, cocoa and cocoa butter.
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