Centella
Centella is a genus of about 55 species of flowering plants in the Apiaceae family.[1] The most prominent species, Centella asiatica, commonly known as gotu kola, Indian pennywort, or Asian pennywort, is a herbaceous, flowering perennial plant characterized by its creeping habit, fan-shaped green leaves, and small white or pinkish flowers.[2] Native to tropical swampy areas of Southeast Asia and Australia, C. asiatica thrives in moist environments up to 1,800 meters elevation and has spread to subtropical and tropical regions worldwide, including parts of Africa, Madagascar, and the Pacific.[3] This clonal creeper has been utilized for millennia in traditional Ayurvedic and Chinese medicine as a versatile remedy, often consumed as a vegetable, tea, or extract for its reputed cognitive, wound-healing, and adaptogenic effects.[2] The plant's pharmacological profile stems from over 100 bioactive compounds, prominently featuring pentacyclic triterpenoid glycosides such as asiaticoside, madecassoside, and centelloside, along with their aglycones like asiatic acid and madecassic acid, as well as flavonoids, sterols, and essential oils.[2] These constituents contribute to its documented activities, including anti-inflammatory, antioxidant, neuroprotective, anxiolytic, and antimicrobial properties, supported by in vitro and in vivo studies.[3] Traditionally, C. asiatica has treated a range of conditions such as skin disorders (e.g., psoriasis, eczema, leprosy), venous insufficiency, anxiety, and memory impairment, with modern research exploring its potential in wound repair, cognitive enhancement, and even anticancer applications.[2] Beyond medicine, Centella asiatica holds cultural significance as a "miracle elixir" in ancient Chinese texts and a key herb in the Indian pharmacopoeia since the 19th century, though sustainable harvesting is challenged by overexploitation in its native habitats.[3][4] Its versatility extends to cosmetology for improving skin elasticity and treating hypertrophic scars, underscoring its role as a bridge between ethnobotany and contemporary pharmacology.[2]Taxonomy and Description
Morphological Characteristics
Plants in the genus Centella are primarily low-growing, herbaceous perennials, often procumbent or sprawling, with slender, creeping stolons that root at the nodes and can extend up to 1 meter in length.[5][6] These stolons enable the formation of dense mats, with plants typically reaching heights of 5–20 cm, though some species may grow taller up to 1.5 m in erect forms.[6] The root system is fibrous and shallow, facilitating rapid vegetative spread in suitable conditions.[6] Leaves are long-stalked (petiolate), with petioles ranging from 5–168 mm, and blades that are simple, rounded to reniform in shape, measuring 2–6 cm in diameter, often featuring palmate or reticulate venation.[5][6] The leaf margins vary from entire to serrate or crenate, and the blades may be solitary or clustered, with cordate bases and no stipules.[5][6] Flowers are small, actinomorphic, and hermaphroditic or polygamous, borne in simple axillary umbels on short peduncles, with 1–9 flowers per umbellule surrounded by 2–4 bracts.[5] Petal color ranges from greenish-white to pinkish, crimson, or purple, with incurved petals lacking distinct apical lobules and obsolete calyx teeth.[5][6] The fruits are schizocarpic, dorsiventrally flattened mericarps, 1.5–7 mm long and wide, with prominent primary and secondary ribs, a narrow commissure, and glabrous to pilose surfaces; some species exhibit thin wings along the margins.[5][6] While shared traits define the genus, variations occur among species, including differences in stolon thickness, leaf margin dentation (from entire to deeply lobed with up to 41 teeth), and indumentum (glabrous to pubescent).[6] Some species are semi-aquatic, adapting to wetter habits with more robust stolons, whereas others remain strictly terrestrial.[6] The genus belongs to the Apiaceae subfamily Mackinlayoideae, reflecting its distinctive umbelliferous morphology.[5]Classification and Etymology
Centella is a genus within the family Apiaceae, subfamily Mackinlayoideae, placed in the order Apiales under the class Magnoliopsida (eudicots), subclass Asterids, phylum Angiospermae (flowering plants), clade Tracheophyta (vascular plants), and kingdom Plantae.[1][7][8] Historically, species now assigned to Centella were often classified under the genus Hydrocotyle within the Apiaceae or sometimes placed in the family Araliaceae due to morphological similarities such as umbellate inflorescences.[9][10] Molecular phylogenetic studies, including analyses of 18S rDNA and rbcL sequences, have confirmed the distinct placement of Centella within the Apiaceae subfamily Mackinlayoideae since the early 2000s, resolving earlier ambiguities based on vegetative and reproductive traits.[11][12] The genus Centella L., first validly published by Carl Linnaeus in 1763, has the synonym Trisanthus Lour. and currently includes 55 accepted species according to recent taxonomic assessments.[1][13] The name "Centella" derives from the Latin words centum (hundred) and folium (leaf), likely referring to the plant's tendency to produce numerous leaves in dense growth.[14] Common names such as pennywort arise from the coin-like shape of the leaves in many species.[7] The type species is Centella asiatica (L.) Urb., originally described as Hydrocotyle asiatica by Linnaeus in 1753 and later transferred to Centella by Ignatz Urban in 1879.[1][15]Distribution and Habitat
Global Range
Centella species exhibit a predominantly pantropical native distribution, spanning tropical and subtropical regions across Africa, Asia, Australasia, the Pacific, and parts of the Americas and Europe. In Africa, the genus is native to numerous countries including Angola, Benin, Botswana, Madagascar, South Africa, and Zimbabwe, with high species diversity concentrated in tropical zones south of the equator. Asian native ranges encompass the Indian subcontinent, Southeast Asia (e.g., Thailand, Indonesia, Philippines), and China, while extensions reach Australia (e.g., New South Wales, Queensland, Northern Territory) and Pacific islands such as Fiji, New Caledonia, and Samoa. Some species occur in temperate areas, such as the Caucasus region.[1][16] Introduced ranges of Centella have expanded globally through human activities, particularly ornamental and medicinal trade, leading to widespread establishment in the Americas and additional subtropical areas. In the Americas, species like C. asiatica are introduced in the southeastern United States (e.g., Florida, Alabama), Brazil, Colombia, and Mexico, often in disturbed habitats. Further introductions occur in Pacific islands (e.g., Hawaii, Cook Islands) and Atlantic territories (e.g., Bermuda, Ascension Island). C. asiatica is particularly noted as invasive in wetlands, such as those in Dongting Lake, China, and disturbed coastal areas in the US Gulf region, where it forms dense mats that outcompete native vegetation.[1][17][7] Biogeographic patterns reveal centers of diversity in Asia and tropical Africa, reflecting the genus's adaptation to diverse tropical ecosystems. Disjunct distributions in the southern hemisphere, from Madagascar to Australia and parts of South America, suggest ancient dispersal mechanisms, potentially tied to historical continental connections, though modern spreads are largely human-mediated via trade routes established from the 18th century onward.[1][7]Environmental Preferences
Centella species thrive in moist, sandy loam or clay-rich soils, with a preferred pH range of 5.0 to 7.5 that supports nutrient uptake and root development.[18][19] These plants tolerate poorly drained conditions to facilitate their semi-aquatic tendencies but are sensitive to extreme waterlogging, which can lead to root rot and reduced vigor.[7] The genus favors tropical to subtropical climates, where optimal temperatures range from 20°C to 30°C promote robust growth and secondary metabolite production. High humidity levels, often exceeding 70%, are essential to prevent desiccation and mimic their native wetland habitats. While most species are frost-sensitive, certain ones, such as Centella asiatica, can endure light frost down to -5°C for short periods.[20][21][22] In terms of light and water, Centella accommodates partial shade to full sun exposure, though filtered light in humid understories enhances leaf expansion and photosynthetic efficiency. Many species exhibit semi-aquatic adaptations, flourishing along riverbanks, in marshes, and wetlands where consistent soil moisture—without stagnation—sustains their creeping habits.[7][23] Centella demonstrates ecological adaptations including rapid colonization of disturbed, moist sites via stolons, enabling quick establishment in dynamic environments. Allelopathic compounds released by the roots inhibit nearby competitors, particularly in saturated soils, conferring a competitive edge in wet ecosystems. Limitations include intolerance to arid conditions, where drought rapidly impairs growth, and sensitivity to heavy pollution, as the plants readily absorb contaminants from water and soil. Some species are confined to lowlands below 2000 m altitude, beyond which cooler temperatures and reduced humidity hinder survival.[24][25][26][27]Species Diversity
List of Accepted Species
The genus Centella comprises approximately 55 accepted species according to Plants of the World Online (as of 2025), with ongoing taxonomic revisions based on molecular phylogenetic studies that have resolved many historical synonyms since 2000.[1][28] Approximately 20 names remain provisionally accepted pending further clarification.[6] A comprehensive revision in 1995 recognized 45 species, with subsequent additions including endemics such as C. gypsophila Humbert from Madagascar.[6] The majority of species are distributed in the Old World tropics, particularly in Africa, Asia, and Australia, with a few in the New World; most exhibit a creeping habit typical of the genus.[1] Below is an alphabetical list of accepted species with authorities, drawn from the 1995 revision and updated databases (synonyms noted where resolved post-revision). This list includes species from the 1995 revision and select updates; for a full current list, refer to Plants of the World Online.| Species | Authority | Key Notes/Synonyms |
|---|---|---|
| Centella affinis | (Eckl. & Zeyh.) Adamson | - |
| Centella alpina | (Eckl. & Zeyh.) M. Schubert & B.-E. van Wyk | - |
| Centella annua | M. Schubert & B.-E. van Wyk | New species described in revision |
| Centella asiatica | (L.) Urb. | Type species; synonym: Hydrocotyle asiatica L. |
| Centella brachycarpa | M. Schubert & B.-E. van Wyk | New species |
| Centella calcaria | M. Schubert & B.-E. van Wyk | New species |
| Centella calliodus | (Cham. & Schltdl.) Drude | - |
| Centella capensis | (L.) Domin | - |
| Centella cochlearia | (Domin) Adamson | - |
| Centella cordata | (Thunb.) Adamson | Elevated from varietal status |
| Centella crenata | M. Schubert & B.-E. van Wyk | New species |
| Centella cryptocarpa | M. Schubert & B.-E. van Wyk | New species |
| Centella debilis | (Eckl. & Zeyh.) Drude | - |
| Centella difformis | (Eckl. & Zeyh.) Adamson | Synonym: Hydrocotyle difformis Eckl. & Zeyh. |
| Centella dolichocarpa | M. Schubert & B.-E. van Wyk | New species |
| Centella erecta | (L.f.) Fernald | - |
| Centella eriantha | (A.Rich.) Drude | - |
| Centella flexuosa | (Eckl. & Zeyh.) Drude | - |
| Centella fourcadei | Adamson | Possible hybrid |
| Centella fusca | (Eckl. & Zeyh.) Adamson | Synonyms: Hydrocotyle fusca, H. trichophylla |
| Centella glabra | (Adamson) A.Pillai & S.Muraleedharan | Post-revision addition |
| Centella glabrata | L. | Synonym: Hydrocotyle glabrata (L.) L.f. |
| Centella glauca | M. Schubert & B.-E. van Wyk | New species; related to C. macrocarpa |
| Centella graminifolia | (Burm.f.) Adamson | Varieties include var. graminifolia, var. natalensis |
| Centella gymnocarpa | M. Schubert & B.-E. van Wyk | New species |
| Centella gypsophila | Humbert | Endemic to Madagascar; post-revision |
| Centella lanata | Compton | - |
| Centella linifolia | (L.f.) Drude | - |
| Centella longifolia | (Adamson) M. Schubert & B.-E. van Wyk | Elevated from C. montana var. longifolia |
| Centella macrocarpa | (A.Rich.) Adamson | Transitional with C. virgata |
| Centella macrodus | (Spreng.) B.L. Burtt | - |
| Centella montana | (Cham. & Schltdl.) Domin | - |
| Centella obtriangularis | Cannon | - |
| Centella pilosa | M. Schubert & B.-E. van Wyk | New species; possible hybrid |
| Centella pottebergensis | Adamson | - |
| Centella restioides | Adamson | - |
| Centella rigescens | (Eckl. & Zeyh.) M. Schubert & B.-E. van Wyk | Reinstated species |
| Centella rotundifolia | (Adamson) M. Schubert & B.-E. van Wyk | Elevated to species rank |
| Centella rupestris | (Eckl. & Zeyh.) Adamson | Synonym: Hydrocotyle rupestris Eckl. & Zeyh. |
| Centella sessilis | (L.) Fernald | Synonym: C. didymocarpa |
| Centella stenophylla | Adamson | - |
| Centella ternata | M. Schubert & B.-E. van Wyk | New species |
| Centella thesioides | M. Schubert & B.-E. van Wyk | New species |
| Centella tridentata | (L.f.) Domin | Varieties include var. tridentata, var. litoralis |
| Centella triloba | (Thunb.) Drude | - |
| Centella umbellata | M. Schubert & B.-E. van Wyk | New species |
| Centella villosa | L. | Synonyms: C. lasiophylla, C. scabra |
| Centella virgata | (L.f.) Drude | Transitional with C. macrocarpa |