In this article we will discuss about:- 1. General Characters of Solanaceae 2. Floral Formula of Solanaceae 3. Number and Distribution 4. Range of Floral Structures 5. Common Plants 6. Affinity and Economic Importance.
General Characters of Solanaceae:
Plants—herbs or shrubs, rarely small trees, sometimes climbing. Leaves—alternate, simple, often lobed, exstipulate. Inflorescence— often cymose. Flowers—regular, sometimes zygomorphic, bisexual, hypogynous. Sepals—(5), persistent, often enlarging in the fruit, imbricate. Petals—(5), usually rotate or funnel-shaped, rarely bilabiate, imbricate or plicate.
Stamens—usually 5, alternating with the corolla- lobes, rarely 4, didynamous (e.g., Brunfelsia, Browallia, Salpiglossis and Schizanthus), epipetalous; anthers bilocular, dehiscing by apical pores or longitudinally. Carpels—(2), obliquely placed; ovary superior, generally 2-celled or falsely 3-5-celled with numerous anatropous ovules on axile placenta; stigma bilobed. Fruit—usually many-seeded berry, sometimes capsule (e.g., Datura). Seeds—more or less uniform, albuminous. Embryo—usually curved, sometimes straight.
Floral Formula of Solanaceae:
Number and Distribution of Solanaceae:
This family consists of about 85 genera and over 2,200 species which are widely distributed, throughout tropical and temperate regions.
Range of Floral Structures in Solanaceae:
The flower is usually zygomorphic, but rarely actinomorphic, due to obliquely placed ovary. The corolla is found to be regular as in Solanum, which consists of rotate corolla, or the bell-shaped corolla of Atropa, or irregular to some extent, as in Hyoscyamus.
Zygomorphy is very prominent in Salpiglossis. In this genus there are two or four fertile stamens. The corolla may be two-lipped, as in Schizanthus. The stamens are usually unequal in their length.
In Capsicum the ovary is 1-celled in the upper portion. In many genera false partitions are laid down as a result of which 3-5-celled chambers are formed. In Datura, 4-celled chamber is seen, but in Nicandra, the ovary becomes 3-5-celled.
The number of ovules is generally numerous but occasionally few ovules are found, as in Cestrum.
Common Plants of Solanaceae:
(1) Brinjal or Egg-plant (Solanum melongena L.), a common herb cultivated throughout India.
(2) Potato (Solanum tuberosum L.).
(3) Solanum xanthocarpum Schrad. & Wendle, a prickly weed found on roadsides much used by Indian Kabirajes.
(4) Solanum torvum Swartz., a common shrub.
(5) Solatium ferox L.
(6) Solanum verbascifolium L., a large shrub or Small tree about 12 ft. in height.
(7) Nightshade (Solanum nigrum L.), a common weed found everywhere.
(8) Solanum indicum L., a prickly herb commonly found on roadsides and rubbish heaps.
(9) Solanum trilobatum L., a prickly climbing plant found in salt-lakes near Calcutta.
(10) Tomato (Lycopersicum esculentum Mill. = S. lycopersicum Mill.), a tall herb, commonly cultivated for globose pulpy fruits.
(11) Chilli or red pepper (Capsicum frutescens L. = C. annum L.), cultivated for the scarlet or orange-yellow fruits which are used as condiment.
(12) Thorn-apple (Datura fastuosa L.= D. metel L.), a common herb whose seeds are highly poisonous; Jimson weed (D. stramonium L.), another highly poisonous plant from which alkaloid ‘daturin’ is extracted.
(13) Tobacco (Nicotiana tabacum L.), a small shrub with sticky glandular hairs.
(14) Nicotiana plumbaginifolia Viv., a common weed.
(15) Withania somnifera Dun., a medicinal plant cultivated in gardens.
(16) Cape gooseberry or Ground cherry (Physalis peruviana L.), commonly cultivated for the edible fruits which lie concealed within accrescent calyx; P. minima L., a common weed in waste places and on the borders of cultivated land.
(17) Cestrum nocturnum Murray, a common garden plant, the flowers of which emit a sweet odour at night.
(18) Solanum macranthum, a tree-like plant with pale-blue flowers, often cultivated in gardens.
(19) Solanum seaforthianum, a climber, very commonly found in Darjeeling with small white flowers.
(20) Brunfelsia, Salpiglossis, Schizanthus and Petunia are garden plants.
(21) Deadly nightshade (Atropa belladonna L.).
(22) Woody nightshade or Bitter-sweet (Solanum dulcamara L.)., and
(23) Henbane (Hyoscyamus niger L.), are medicinal plants.
(24) Browallia elata L., an annual garden herb.
(25) Solanum glaucum, very common at Diamond Harbour.
(26) Cestrum diurnum, very common on roadsides.
Affinity and Economic Importance of Solanaceae:
This family is allied to Scrophulariaceae but distinguished by the form of the corolla, number of stamens and oblique position of carpels. It differs from Convolvulaceae in having numerous seeds.
According to Engler, this family occupies a position under order Tubiflorae in the subseries Solanineae. Hutchinson considers this family is related to Convolvulaceae and Boraginaceae. Wettstein accepts the view that Solanaceae is closely associated with Convolvulaceae, that is why he has put the family under Tubiflorae.
Rendle is of opinion that the family Solanaceae be placed under Tubiflorae. Hallier considers it as a primitive member of the Tubiflorae and has derived from Linaceae.
Economic Importance of Solanaceae:
This family is of considerable economic importance. Some plants are used as vegetables, such as, Solanum tuberosum (potato), S. melongena (brinjal), S. lycopersicum (tomato), Capsicum and others. Some genera are important from medicinal standpoint of view, such as, Atropa, Datura, Solanum, Withania, Hyoscyamus, etc.
Tobacco (Nicotiana tabacum) is an important economic plant. Alkaloids, such as, nicotin and daturin are obtained from Nicotiana tabacum and Datura stramonium respectively. Some plants are ornamentals such as, Petunia, Cestrum, Datura, Browallia, Brunfelsia, Schizanthus, etc.
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