Dymondia is a genus of flowering plants in the daisy family, Asteraceae (order Asterales), containing a single known species, Dymondia margaretae. It is endemic to the Western Cape of South Africa, restricted to the Southern Overberg region between Agulhas and Potberg, where it grows at low altitudes (160-200 m) on well-drained, sandy coastal flats and seasonally wet pans in slightly alkaline soils.
The plant is an evergreen perennial reaching only about 50 mm (2 in) in height, spreading via a creeping, much-branched rhizome to form a dense, flat, carpet-like mat. Its basal leaf rosettes carry small, rigid, linear-oblanceolate leaves with shallow marginal teeth; the upper surface is dark green and hairless, while the incurved margins expose a pale, felt-like underside — a feature that becomes more visible when the plant is drought-stressed and its leaves curl. Small, stalkless, daisy-like yellow flower heads around 25 mm across appear year-round, peaking in spring and early summer, combining female ray florets with bisexual disc florets; the resulting fruit is a hairless cypsela topped with a two-ringed pappus that aids wind dispersal. Various insects, including bees, beetles, and butterflies, visit the flowers, though confirmed pollinators have not been established.
The genus and species commemorate Margaret Elizabeth Dryden-Dymond, a horticulturalist, botanical collector, and teacher on the staff of Kirstenbosch National Botanical Garden, who first collected the plant near Bredasdorp in 1933. That original population was never relocated despite repeated searches, and the plant was not recorded again until 1949, with a further find in Bontebok National Park the following year. Within Asteraceae, Dymondia's closest resemblance is to the genera Landtia and Arctotheca.
Although classified as endangered in the wild — its natural range covers under 5,000 km² and is severely fragmented, with continuing habitat decline — Dymondia margaretae has become widely grown in horticulture worldwide. Its low, drought-tolerant, foot-traffic-resistant mat makes it a popular water-wise lawn substitute and filler between pavers and stepping stones, valued for erosion control on slopes as well as its ornamental blue-grey foliage.
Etymology
The genus and its only species, Dymondia margaretae, commemorate Margaret Elizabeth Dryden-Dymond, a South African horticulturalist, botanical collector and teacher on the Kirstenbosch National Botanical Garden staff (1909-1952), who first collected the plant near Bredasdorp in 1933.
Distribution
Dymondia margaretae is endemic to the Western Cape of South Africa, restricted to the Southern Overberg area between Agulhas and Potberg at altitudes of 160-200 m, growing on well-drained sandy coastal flats and seasonally wet pans in slightly alkaline soils.
Ecology
Flowers are visited by a range of insects including bees, beetles and butterflies, though the actual pollinator(s) remain unconfirmed. Seeds are dispersed by wind, aided by a hairy pappus.
Cultivation
Dymondia margaretae is a hardy, drought-tolerant groundcover widely grown outside its native range. It forms a dense, flat mat only about 5 cm (2 in) tall, spreading slowly but non-invasively, and is valued as a water-wise lawn substitute — sometimes nicknamed "living cement" — tolerating light to medium foot traffic and handling well as a filler between flagstones, pavers, and stepping stones. Deep roots act as water reservoirs, giving it strong drought tolerance and making it useful for erosion control on slopes, though it can die back in unsightly patches if overwatered. It prefers full sun to part shade and very sandy, well-drained soil, tolerates light frost and is cold hardy to about -7°C (20°F), doing best below 37°C (100°F) with adequate water. It is considered safe and non-toxic for pets.
Conservation
Dymondia margaretae is assessed as endangered, facing a very high risk of extinction in the wild: its range covers an estimated area of less than 5,000 km², is severely fragmented or limited to five or fewer locations, and continues to decline in extent and habitat quality. Its horticultural popularity worldwide contrasts sharply with its precarious wild status.
History
First collected in 1933 near Bredasdorp on a Kirstenbosch expedition, the original population was never relocated despite repeated searches. No further records exist until 1949, followed by a 1950 discovery in Bontebok National Park; the most recent herbarium collection was made in 2005.
Propagation
Dymondia margaretae can be grown from seed, cuttings, or division, with division followed by tip cuttings being the easiest method. Propagation is best done in late winter or early spring; tip cuttings root within 3-4 weeks in well-drained sandy soil with the aid of rooting hormone.
Taxonomy Notes
Dymondia is a monotypic genus in Asteraceae (order Asterales), containing only Dymondia margaretae. Its closest resemblance within the family is to the genera Landtia and Arctotheca.
