Asiatic pennywort

''Centella asiatica'', commonly known as gotu kola, kodavan, Indian pennywort and Asiatic pennywort, is a herbaceous, perennial plant in the flowering plant family Apiaceae. It is native to tropical regions of Africa, Asia, Australia, and islands in the western Pacific Ocean. It is consumed as a culinary vegetable and is used in traditional medicine.

Description

''Centella'' grows in temperate and tropical swampy areas in many regions of the world. The stems are slender, creeping stolons, green to reddish-green in color, connecting plants to each other. It has long-stalked, green, rounded apices which have smooth texture with palmately netted veins. The leaves are borne on pericladial petioles, around . The rootstock consists of rhizomes, growing vertically down. They are creamish in color and covered with root hairs.

The flowers are white or crimson in color, born in small, rounded bunches (umbels) near the surface of the soil. Each flower is partly enclosed in two green bracts. The hermaphrodite flowers are minute in size, less than , with five to six corolla lobes per flower. Each flower bears five stamens and two styles. The fruit are densely reticulate, distinguishing it from species of ''Hydrocotyle'' which have smooth, ribbed or warty fruit. The crop matures in three months, and the whole plant, including the roots, is harvested manually. It is a highly invasive plant, rated as "high risk". ''Centella'' has numerous common names in its regions of distribution.

Habitat

''Centella asiatica'' is indigenous to the Indian subcontinent, Southeast Asia, and wetland regions of the Southeastern US. Because the plant is aquatic, it is especially sensitive to biological and chemical pollutants in the water, which may be absorbed into the plant. It can be cultivated in drier soils as long as they are watered regularly enough (such as in a home garden arrangement).

Chemistry

''Centella'' contains pentacyclic triterpenoids, including asiaticoside, brahmoside, asiatic acid, and brahmic acid (madecassic acid). Other constituents include centellose, centelloside, and madecassoside.

Culinary use

In Burmese cuisine, raw pennywort is used as the main constituent in a salad mixed with onions, crushed peanuts, bean powder and seasoned with lime juice and fish sauce. Centella is used as a leafy green in Sri Lankan cuisine, being the predominantly locally available leafy green, where it is called . It is most often prepared as , a traditional accompaniment to rice and vegetarian dishes, such as , and jackfruit or pumpkin curry. It is considered nutritious. In addition to finely chopped plants, the may be eaten with grated coconut, diced shallots, lime (or lemon) juice, and sea salt. Additional ingredients are finely chopped green chilis, chili powder, turmeric powder, or chopped carrots. The ''Centella'' fruit-bearing structures are discarded from the due to their intense bitter taste. A variation of porridge known as is also made with in Sri Lanka. is made with well-boiled red rice with some extra liquid, coconut milk first extract, and purée. The porridge is accompanied with jaggery for sweetness. ''Centella'' leaves are also used in modern sweet pennywort drinks and herbal teas. In addition the leaves are served stir-fried whole in coconut oil, or cooked in coconut milk with garlic or .

In Indonesia, the leaves are used for ''sambai oi peuga-ga'', an Aceh type of salad, and is also mixed into asinan in Bogor, Vietnam and Thailand, this leaf is used for preparing a drink or can be eaten in raw form in salads or cold rolls. In Bangkok, vendors in the Chatuchak Weekend Market sell it alongside coconut, roselle, chrysanthemum, orange and other health drinks. In Malay cuisine it is known as pegaga, and the leaves of this plant are used for ulam, a type of vegetable salad. ''C. asiatica'' is widely used in various Indian regional cuisines.
In Bangladesh and India (specifically in West Bengal), Centella is called Thankuni Pata and used in various dishes, one of the most appetising of which is the pakora-like snack called Thankuni Patar Bora; made of mashed ''Centella'', lentils, julienne-ed onion and green chilli.

Traditional medicine

In traditional medicine, ''C. asiatica'' has been used to treat various disorders and minor wounds, although clinical efficacy and safety have not been scientifically confirmed. Contact dermatitis and skin irritation can result from topical application. Drowsiness may occur after consuming it. The herb may have adverse effects on liver function when used over many months.

Agriculture

In the context of phytoremediation, ''C. asiatica'' is a potential phytoextraction tool owing to its ability to take up and translocate metals from root to shoot when grown in soils contaminated by heavy metals.

Gallery

File:Centella asiatica - Flickr - Kevin Thiele.jpg, Emerging flowers
File:Centella asiatica - Flickr - Kevin Thiele (1).jpg, Flower, close-up
File:Centella asiatica in Karnataka.jpg, ''Centella asiatica'', India
File:Nam bai bua bok.JPG, ''Bai bua bok'' as a beverage, Thailand

References

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Mackinlayoideae
Edible Apiaceae
Dietary supplements
Flora of temperate Asia
Flora of tropical Asia
Plants used in Ayurveda
Plants used in traditional African medicine
Plants used in traditional Chinese medicine
Plants described in 1753
Taxa named by Carl Linnaeus