In this article we will discuss about:- 1. General Features of the Nymphaeaceae 2. Floral Range in the Nymphaeaceae 3. Divisions 4. Position and Affinity 5. Number and Distribution 6. Commonly Occurring Plants 7. Economic Aspects.
General Features of the Nymphaeaceae:
Habit – Aquatic herbs, with a perennial rhizome.
Leaves – Floating, peltate or falsely so, long petioled.
Flowers – Solitary showy, long peduncled, bisexual, regular, hypogynous to perigynous, thalamus cup shaped and fleshy.
Perianth – Segments many, free spiral, gradually passing from sepals to petals and petals to stamens.
Androecium – Stamens many, free, adnate to thalamus; filaments foliaceous.
Gynoecium – Carpels many, free enveloped by thalamus; ovary 1- or more-locular with ovules disposed on lamellate or parietel placentae; stigma sessile, radiating, often with appendages.
Fruit – Berry-like fleshy mass.
Seeds – Arillate with both perisperm and endosperm; embryo straight.
Floral Range in the Nymphaeaceae:
No other family has such variations in the structure of the flower as the Nymphaeaceae. Since this is a distinct morphological feature among certain genera, this has been the basis for the divisions of the family.
Divisions of the Nymphaeaceae:
On the basis of the construction of floral parts, the Nymphaeaceae is divided into three subfamilies:
Subfamily I Cabomboideae:
Flowers cyclic, trimerous and hypogynous. Perianth segments in two whorls of 3 each, outer forming sepals and inner petals. Stamens 6. Carpels 3, free. Examples: Brasenia and Cabomba.
Subfamily II Nelumbonoideae:
Flowers acyclic and hypogynous. Perianth segments indefinite, outer whorl of 5 sepals. Stamens indefinite. Carpels many, free. Example: Nelumbo.
Subfamily III Nymphaeoideae:
Flowers hypogynous, perigynous or epigynous. Perianth segments indefinite whorls of 4-5 each. Stamens indefinite. Carpels many, united. Examples: Euryale, Nuphar, Nymphaea, etc.
Position and Affinity of the Nymphaeaceae:
The Nymphaeaceae is a primitive family and comes under the herbaceous Ranales. Most botanists have accepted the family as composed of three distinct subfamilies. But Bessey treated each subfamily as a well-defined family, included the Cabombaceae and Nelumbaceae in the Ranales and removed the Nymphaeaceae to the Rhoeadales on the criterion of syncarpous pistil. Hutchinson, while accepting the Cambombaceae, retained the other two subfamilies within the scope of the Nymphaeaceae.
An affinity of the Nymphaeaceae can be traced to the Ranunculaceae through the Cabombaceae. The scattered vascular bundles and arillate seeds of the Nymphaeaceae recall those of the Berberidaceae. Moreover, points favouring the alliance of the Nymphaeaceae with the Papaveraceae include the presence of latex in tissues, large peltate-rayed stigma and laminal placentation.
Some investigators have drawn our attention to a possible relationship between the Nymphaeaceae and Alismataceae. The aquatic habit of the plants and structure of the ovary are essentially similar in the two families, but further connections are difficult to pursue.
Number and Distribution of the Nymphaeaceae:
The Nymphaeaceae consists of nine genera and over 90 species. In general, plants of this family are noticed in fresh waters of the world.
Commonly Occurring Plants of the Nymphaeaceae:
Euryale ferox Salisb. is known for the abundant development of prickles on the surface of leaves and fruits.
Lotus (Nelumbo nucifera Gaertn.), Yellow Waterlily (Nuphar luteum Sibth. & Sm.) and Waterlily (Nymphaea nouchali Burm. f.) are found in tanks.
Economic Aspects of the Nymphaeaceae:
The plants of the Nymphaeaceae are mainly important for the beauty of their flowers which exhibit great variety and brilliancy of colours in the tropics. Cabomba is a popular oxygenator for aquaria. The fruits and rhizomatous stem of most of the water-lilies are edible. The seeds of Euryale and Nymphaea are also consumed.
The family is characterised by the single lateral branch produced at a node, dichotomously dissected serrulate leaves, solitary unisexual perianthless flowers and unicarpellate pistil.
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