Centella cordifolia, commonly known as swamp pennywort or arthritis herb,^[2] is a trailing perennial herb^[3] native to Australia.^[4] The species is common in preferred local environments.^[5][6] It potentially has medicinal purposes and indigenous cultural significance.^[7] C. cordifolia can be sourced commercially at Australian plant nurseries.^[5]

Quick Facts Centella cordifolia, Scientific classification ...

Centella cordifolia
Pressing of C. cordifolia
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Apiales
Family:	Apiaceae
Genus:	Centella
Species:	C. cordifolia
Binomial name
Centella cordifolia (Hook.f.) Nannf.
Synonyms[1]
Hydrocotyle cordifolia Hook.f.

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Centella cordifolia is a groundcover herb that can grow up to 15 cm (5.9 in) tall,^[4] and typically stretches 1–2 m (3 ft 3 in – 6 ft 7 in) wide.^[5]

Leaves are heart-shaped (cordate), glabrescent, glossy and dark green.^[4] The lamina is 1–3 cm (0.39–1.18 in) in length (with a similarly sized width), with five to seven veins and scarious margins.^[8] When exposed directly to the sun, the leaves sit lowered, towards the ground, whereas in the shade they will stand upright.^[4] The petiole has a purple tint, sheathing and broad at the base, and can be up to five times the length of the lamina.^[8]

Flowers occur in subsessile umbels in an ovate shape, 3 mm (0.12 in) in length and each containing two to three florets.^[8] Petals are purple or white,^[5] ovate, and approximately 1.5 mm (0.059 in) in length.^[8] Sepals form a very small, lobed ring, and at the base are two involucral bracts.^[8] Anthers are dark purple.^[8] Flowering times for C. cordifolia occur between late summer (December) to early autumn (March).^[8][9]

Fruit is small, rounded, laterally compressed and contains seeds.^[9] five longitudinal ribs span the mericarp,^[8] which is 2.5–3 mm (0.098–0.118 in) in length and 4–5 mm (0.16–0.20 in) in width.^[8] Small hairs towards the apex can be present, but in general the fruit is glabrous.^[8]

Distinguishing C. cordifolia from other Centella species can be difficult, particularly from C. asiatica, which also inhabits parts of Australia.^[10] The leaf margins of C. cordifolia are more serrate, whereas C. asiatica have more dentate margins.^[10] C. cordifolia also has mat-like growth habit, which can be distinguished from other Centella species that have greater vertical and spreading growth habits.^[10]

Centella cordifolia is native to Australia, growing in parts of Western Australia, South Australia, New South Wales, Victoria and Tasmania.^[8] However, the species has limited records and distribution lacks an extensive understanding.^[8]

The herb grows in damp, poorly drained environments, including marshy soils or shallow waters.^[5] Sun exposure can range from full to partial shade.^[5] It is intolerant to phosphorus and moderately frost tolerant.^[11]

Centella cordifolia forms part of the understory in the various damp environments it inhabits.^[11] It can provide a habitat for frogs.^[7] It's root system stabilizes the damp soils it can grow in, preventing erosion.^[12]

Centella cordifolia is known to treat rheumatism and arthritis,^[7][2] though widespread adoption and evidence for this is limited. The herb is said to have an indigenous cultural significance,^[7] again with limited information available.

C. cordifolia is closely related to Centella asiatica^[10] and their uses may be interchangeable.^[13] C. asiatica is widespread across Australia, Africa, Asia, North and South America, with well-known cultural, medicinal and culinary uses.^[13] In a 2017 study published by Frontiers in Plant Science.^[10] C. cordifolia was found to be genetically and chemically similar to C. asiatica, when comparing three Centella species (C. cordifolia, C. asiatica and C. erecta).