Water Lilies
Water Lilies
Ecological and economic importance
The water lily, yellow water lily, lotus, and several other aquatic plants are about 60 species of aquatic herbs that make up the family Nymphaeaceae. These plants occur in shallow, fresh waterbodies from the boreal to the tropical zones. The usual habitats of these plants are ponds and shallow water around lake edges, as well as slowly-flowing pools and stagnant backwaters in streams and rivers.
Water lilies are perennial, herbaceous plants. Their green foliage dies back each year at the end of the growing season, but the plant perennates itself by issuing new growth from a long-lived rhizome occurring in the surface sediment. The foliage of most species in the family is comprised of simple, glossy, dark-green leaves, which float on the water surface. The solitary, perfect (or bisexual) flowers are held just above the water surface, and are large and showy, with numerous petals and a strong fragrance, making them highly attractive to pollinating insects. In most species, the flowers open at dawn, and close at dusk for the night.
On breezy days, the leaves and flowers of water lilies appear to dance lightly on the water surface. This superficial aesthetic led to the choosing of the family name of these plants (Nymphaeaceae) by the famous Swedish naturalist Carolus Linnaeus (1707-1778), who likened the water lilies to frolicking nymphs.
Species of water lilies
Species of water lilies are prominent in many shallow-water habitats, from the boreal zones to the tropics. The genera are described below, with particular reference to species occurring in North America.
There are about 40 species of water lily (Nymphaea spp.). The white water lilies (Nymphaea odorata and Nymphaea tuberosa ) are widespread in North America, and have large, roundish leaves with a triangular cleft at one end, at the point of which the petiole attaches. The large flowers are colored white, or rarely pink. The blue water lily (Nymphaea elegans ) occurs in the southern United States and down south into Latin America, and has bluish or pale violet flowers.
The are about 10 species of yellow water lilies or spatterdock (Nuphar spp.), including the widely dispersed North American species Nuphar microphyllum, N. variegatum, and N. advena. The floating leaves of these plants are rather oblong in shape, with a basal cleft, at the apex of which the petiole attaches. The flowers are greenish on the outside, and are bright-yellow or sometimes reddish on the inside.
The water-shield (Brasenia schreberi ) occurs widely in ponds and shallow waters along lake and pond shores in North America, Central and northern South America, and Eurasia. The petiole joins the oblong, floating leaves at their center, a morphology known as peltate. The flowers are relatively small, and are colored a dull red.
There are about seven species of fanwort or water-shield, including Cabomba caroliniana, a widespread species of pools and quiet streams over much of North America. This species has dense, oppositely arranged, finely dissected, submersed foliage, as well as small, alternately arranged, floating leaves. The six-petalled flowers are relatively small, and are colored white or lavender.
The lotus lily or water chinquapin (Nelumbo lutea ) occurs in scattered populations in North America. The roundish leaves float on the water surface, or are held slightly above, and the petiole is attached at the middle. The flowers are pale-yellow in color. The Oriental sacred lotus (N. nucifera ) and sacred lotus (N. nelumbo ) are native species in Asia, and are widely cultivated ornamentals there, and sometimes in North America and Europe.
The largest-leafed species in the Nymphaeaceae is the royal water lily (Victoria amazonica ) oftropicalSouth
KEY TERMS
Hydrophyte —A perennial plant that is adapted to growing in permanently aquatic habitats.
Perfect —In the botanical sense, this refers to flowers that are bisexual, containing both male and female reproductive parts.
America, whose floating leaves can be larger than one-meter across, and can support the weight of a child.
Ecological and economic importance
Species in the water lily family are important components of the plant communities of most freshwater lakes, ponds, and other shallow-water habitats. They provide food for many types of herbivorous animals, and a habitat substrate for others, such as the long-toed birds known as “lily-trotters” or jacanas (family Jacanidae, including Jacana spinosa of Central and South America).
Species of water lilies provide a beautiful aesthetic to aquatic habitats, which is greatly appreciated by many people. The sacred lotuses (Nelumbo nucifera and N. nelumbo ) are especially important in this regard in a number of cultures. This is particularly true in India, China, Japan, and elsewhere in Asia, where sacred lotuses are featured prominently in horticultural plantings in many gardens and parks, in paintings and other visual arts, in architectural motifs and decorations, and as symbolism in literature.
Several other species in the water lily family are of minor economic importance as horticultural plants, because of the pleasing aesthetics of their floating leaves, as well as their attractive flowers. Various species of water lilies and spatterdocks are commonly planted in gardens which have shallow ponds incorporated into their design. A water lily native to North America, Nymphaea odorata, is commercially available in rose-hued flowers, as well as the wild-type white color.
Another minor use of some species is in the production of food for fishes grown in tropical aquaculture. Water lilies growing in commercial fish ponds are eaten as a food by certain herbivorous fish, and thereby contribute to the productivity of the agricultural ecosystem.
Some people eat the seeds of Nymphaea, Nelumbo, and Victoria, but this is a relatively minor use of the plants.
Resources
BOOKS
Judd, Walter S., Christopher Campbell, Elizabeth A. Kellogg, Michael J. Donoghue, and Peter Stevens. Plant Systematics: A Phylogenetic Approach. 2nd ed. with CD-ROM. Suderland, MD: Sinauer, 2002.
Slocum, Perry D. Waterlilies and Lotuses: Species, Cultivars, and New Hybrids. Portland, Oregon: Timber Press, 2005.