Wednesday, 29 October 2008
Nymphea pubescens(Water lily)
FAMILY OF THE WEEK : NYMPHACEAE
The family is represented by 8 genera and about 90 species most abundant in tropics. In India there are 4 genera and 7 species occurring throughout India.
Vegetative characters :
They are perennial aquatic herbs with a creeping or erect sympodial rhizome. There is a scattered arrangement of vascular bundles.
The leaves are usually large, simple and long petioled, arising from the root stalk or from the slender floating stem (Cabomba). They are usually floating or sometimes emerged as in Nelumbo. often peltate.
Inflorescence and flowers :
The flowers are axillary, solitary, long peduncled, and float on the surface or raised much above the water(Nelumbo) or partially submerged. The flowers are large showy, often sweet scented, bisexual, actinomorphic, hypogynous or more or less epigynous and acyclic to cyclic.
The calyx and corolla are poorly differentiated. The calyx is composed of 3-5 sepals. The sepals are distinct and green or coloured and petioled.
The corolla is polypetalous with three to indefinite and variously coloured or white showy petals. In Nymphea numerous spirally arranged petals gradually pass into stamens.
The androecium is composed of three to indefinite distinct stamens. The gynoecium is of two to three to numeruos carpels. In Nelumboideae there are a large number of carpels which are embedded separately in round pits which are on the flat upper surface of of a swollen spongy and obconical receptacle.
Fruits and seeds :
In Cabomboideae the fruit is a closed indehiscent follicle with one to three pendulous seeds. In Nelumboideae the fruit is indehiscent one seeded nutlet. The seeds are with a large embryo and with no endo ro perisperm. In Nymphaeoideae the fruit is a spongy berry with numerous seeds and it dehisces by swelling of mucilage. The seeds have small embryo and endosperm and abundant perisperm.
Pollination and seed dispersal :
Bright and showy fragrant flowers favour pollination by insect, flies and small beetles.Seed dispersal is mostly by water. Somespecies of Nuphar, Brasenia, and Cabomba are dispersed by ducks which eat the pulp of these fruits greedily.
Nelumbo nucifera (Lotus) Kamal Nymphaea nauchali(Indian red water Lily) Nymphaea stellata(Indian blue water Lily) Nymphaea alba (European white water Lily) Victoria amazonica(Royal water Lily)
Posted by SATISFIED at 08:55