In this article we will discuss about:- 1. Characters of Nymphaeaceae 2. Distribution of Nymphaeaceae 3. Economic Importance 4. Affinities.
Characters of Nymphaeaceae:
Aquatic herbs with large and peltate leaves; flowers hermaphrodite, hypogynous to epigynous; perianth segments many, spiral, gradually passing from sepals to petals and petals to stamens, stamens many; carpels many in pits of the torus or confluent with it, ovules disposed on lamellate or parietal placentae; fruit a spongy berry or an etaerio of achene or nuts sunken in the pits of a turbinate torus.
A. Vegetative characters:
Habit:
The plants are fresh water aquatic herbs, either annual or perennial, with coloured or watery latex.
Root:
Adventitious, slender, attached to root-stocks (rhizome).
Stem:
Rhizome, rooted in the mud or at the bottom of shallow lake or pond, branched, erect (Victoria) or creeping (Nymphaea).
Leaf:
Alternate, simple, long petioled, floating or immersed; large, broad lamina; sometimes dimorphic (Cabomba), the leaves of Victoria regia, the royal water-lily of South America, are 60-180 cm. in diameter with upturned margins and prickly below.
B. Floral characters:
Inflorescence:
Solitary terminal or axillary on long leafless scape.
Flower:
Large, showy, hermaphrodite, hypogynous to perigynous, acyclic, hemicyclic or rarely cyclic, thalamus freshy, cup shaped, surrounding the carpels, with perianth and stamens adnate to it, fragrant.
Calyx:
Sepals 3 in Brasenia; six to indefinite, free, gradual transition from sepals to petals and petals to stamens.
Corolla:
Petals 3 to 5 or many, polypetalous, large and attractive, inner petals form petaloid staminodia.
Androecium:
Stamens 6 to indefinite, free, adnate to thalamus, spirally arranged, anthers, bithecous, introrse, filament foliaceous, extended as sterile appendages beyond the anther sac.
Gynoecium:
Carpels 3 to many, apocarpous (Cabomboideae and Nelumboideae) or syncarpous (Nymphaeoideae), superior (Nelumbium) or inferior (Vitoria), Unilocular or multilocular, one to many ovules on lamellate or parietal placenta; style short; stigmas as many as carpels, free or united, radiating, often with appendages.
Fruit:
Spongy berry (Nymphaea), an etaerio of achene (Nelumbo) or follicle (Cabomba).
Seed:
Often arillate, endospermic or non-endospermic, embryo straight; perisperm present.
Pollination:
Entomophilous, flowers protogynous; flowers of Euryale are cleistogamous and self-pollinated.
Floral formula:
Distribution of Nymphaeaceae:
It is commonly called “water-lily family”. The family consists of 8 genera and 100 species according to Rendle. It is almost cosmopolitan in distribution except in very cold regions.
Economic Importance of Nymphaeaceae:
The family is not of great economic importance.
1. Food:
The seeds of Nymphaea, Nelumbium are edible due to stored starch. The rhizomes of Nelumbo pentapetala (H. Bhen) are used as vegetable.
2. Medicine:
The flower of Nelumbo nucifera are recommended as cardiac tonic and also in treatment of liver diseases. The dried and powdered rhizomes of Nelumbo nucifera are used to cure piles.
The rhizomes of Nymphaea lotus are used in dysentry.
3. Ornamental:
The plants of Nymphaeaceae are important for their brilliantly coloured flowers. The Nymphaea, Nuphar etc., are cultivated in gardens.
Affinities of Nymphaeaceae:
Nymphaeaceae has affinity with Ranunculaceae through sub-family cabomboideae in apocarpous pistil and spiral arrangement of floral parts. Nymphaeceae resembles Berberidaceae, in arillate seeds. The structure of the ovary and aquatic habit of the plants are similar in Nymphaeaceae and Alismaceae.
Cronquist (1967) suggested Nymphaeales as the probable ancestor of monocotyledons because of following characters:
1. Aquatic habit,
2. Lack of vessels,
3. Absence of cambium in vascular bundle,
4. Laminar placentation, and
5. Perianth.
Primitive characters:
Nymphaeaceae is a primitive family under the herbaceous Ranales:
1. Inflorescence solitary terminal or axillary.
2. Flowers large hermaphrodite, actinomorphic.
3. Spiral arrangement of some floral parts.
4. Perianth lobes free and numerous.
5. Stamens laminate and numerous.
6. Polycarpellary and apocarpous gynoecium in Nelumbo and Caboma.
7. Seeds large and endospermic.
Advanced characters:
1. Herbaceous habit.
2. Sepals and petals 3 each in some.
3. Perigynous and epigynous condition of flowers.
4. Syncarpous gynoecium in Nymphaea, Nuphar.
5. Fruit is etaerio of achenes in Nelumbo.
Common plants of the family:
1. Nelumbo speciosum (Indian lotus) – cultivated in lakes for rhizomes (H. Bhen).
2. Nelumbo nucifer – rose-coloured flowers are the legendry sacred lotus of Hindus.
3. Nuphar luteum – yellow water-lily.
4. Victoria regia – Giant water-lily, a native of South America, 90 to 150 cm. broad floating leaves with upturned margins.
5. Euryale feros – leaves floating, gigantic, densely covered with prickles.
Division of the family and chief genera:
On the basis of the construction of floral parts the family has been divided into three sub-families:
Sub family I. Cabomboideae:
Flowers cyclic, trimerous and hypogynous.
Perianth segments in two whorls of 3 each, outer one forming sepals and inner petals. Stamens 6. Carpels, 3, free. e.g. Cabomba and Brasenia.
Sub-family II. Nelumboideae:
Flowers acyclic and hypogynous. Perianth-segments indefinite, outer whorl of 5 sepals. Stamens indefinite. Carpels many, free e.g. Nelumbo (Nelumbium).
Sub-family III. Nymphaeaoideae:
Flowers hypogynous, perigynous or epigynous. Perianth- segments in indefinite whorls, of 4-5 sepals in each whorl. Stamens indefinite, carpels many, united, e.g. Nymphaea, Nuphar, Victoria, Euryale.