Characteristics of Sundew Plant
Sundew, also known as Drosera, is one of the largest genera of insectivorous plants, cosmopolitan and comprises of 188 species. The family is Droceraceae which consists of plants such as venus-fly trap, pitcher plant, cobra lily and butterworts. They are generally found in wet, marshy places and bogs. Unlike today when they are more of an ornamental plant, insectivorous plants were used for medicinal purposes in the olden days.
Sundew plants trap insects like mosquitoes, flies and gnats with the help of sticky, mucilaginous glands that are present on surface of their leaves. They obtain mineral nutrition from these digested insects. They can be grown everywhere- indoors as well as outdoors. They are easy to handle and do not require much care. Drosera, usually a small perennial, is self-fertilizing and derives nutrition from its traps.
Leaves and their carnivorous property
The plant derives its name from the term sundew (dewdrops) referring to the shining drops of mucilage which are at the tip of the tentacles of drosera. They are small herbaceous plants, usually perennial, and form upright rosettes of various sizes depending on the species.
Drosera plants are characterized by leafy tentacles which are covered by mucilaginous glands on the laminae of their surface. The trapping mechanism involves two types of glands - stalked glands and sessile glands. While the former lures the insect by secreting sweet sticky mucilage that traps the insect and enzymes such as esterase, protease, phosphatase and peroxidase that digest the released nutrients, the latter works by breaking the nutrients and absorbing them.
Sundews are specialized insectivorous plants that are built in such a manner that despite the fact that they do not have enzymes (especially nitrate reductase which is required for the uptake of earth-bound nitrates); they can derive nutrition from the trapped insects. The plant is touch-sensitive and enfolds its leaves as soon as it comes in contact with the prey; this is known as thigmotropism. Some species can also bend their tentacles or body at varying angles to enhance the contact with the prey.
The root system is not developed and is mainly used for absorbing water from the soil and also anchoring the plant body firmly. The main function of the root, that of absorbing nutrients from the soil, is useless as the minerals are derived from its trapped prey.
Flower and propagation
Like most other carnivorous plants, the floral arrangement of drosera is held at a height from the leaf, with the help of a long, sturdy stem. This type of arrangement ensures proper visibility to the pollinators. The flower generally opens in direct sunlight and also moves with the moving position of the sun. Also, the flower is self-fertile and can pollinate itself by closing the flower and dropping the pollens within it. The plant can be propagated through its leaves, black colored seeds, crown and cuttings from the roots.