Plectranthus ernstii

Water Needs

moderate; damp

Plectranthus ernstii
Shrub small
Bonsai Mint / Rubberman

30 cm

Size

Light Conditions

sun; semi-shade

Frost

Tender

Flowers

blue; mauve; October - May; spring summer autumn

damp sun; sun; light shade; rockery; wall; roof garden; wildlife insects

Garden Situation

Habitat

rocky slopes; cliffs; coastal eastern cape; coastal kzn

Region

subtropical east coast; thicket

Rain Season

Summer

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Description

Scarp Forest, in humus-rich pockets of soil in rock crevices on south-facing cliffs. Classified as: Near Threatened (NT) A species is Near Threatened when available evidence indicates that it nearly meets any of the IUCN criteria for Vulnerable, and is therefore likely to become at risk of extinction in the near future. Given the delightful name of ‘Rubberman’, one imagines a shrublet capable of wonderfully contorted shapes. Ernst van Jaarsveld though, who gives his name to this lovely member of the ‘Plec’ family, offers a rather more sedate common name of Bonsai Mint. Rubberman though, captures the imagination. Five cultivars have been introduced: ‘Forster’s Foley’, discovered by Tony Abbott on the Farm Forster’s Foley along the Mtamvuna River, has dark blue, mauve flowers. ‘Msikaba’ from the Msikaba River, has very succulent leaves with elongated branches that tend to droop. ‘Oribi’, is the original form from the Oribi Gorge in KZN, has light green leaves and light blue flowers. Growth form is squat and stems short and is the most popular form used in bonsai work. ‘Mtentu’ has a decumbent growth habit and long stems and originates from the Mtentu River, south of Port Edward. ‘Sikuba’ has elongated drooping stems that are less swollen than the other cultivars. Flowers have darker markings. Description: a succulent herb for sunny to lightly shaded situations, Rubberman can be either erect or low and spreading in habit, though compact in form and slow growing. Unique among Plectranthus species, the Rubberman has thickened or swollen stems with distinct segments and joints along the stems, which can be as thick as 50 mm in diameter at the base. Leaves and flowers are typical of the genus. The ovate leaves 20-3- x 10-25 mm in size, edged with 3-5 teeth, with soft, delicate hairs and pale to redd ish brown gland-dots on the under surface. Tips have a blunt end. Inflorescence is 50-170 mm long, carrying between 2 and 6 flowers. These are beautiful, whitish to light blue, with dark purple markings. The inflorescence stands above the leaves, with the flowers, ar the tip being the first to open. Flowering extends from October through to May. April though is typically Plectranthus season, so expect an April flush of flowers. A relative newcomer to the family, P. ernstii was discovered in 1977, on the cliffs of Oribi Gorge in Southern KZN, by Ernst and Erma van Jaarsveld. Natural habitat is exposed to partially exposed sandstone, in river gorges or Scarp Forest. With stems often covered in lichen plants are well camouflaged among the rocks. Depending on season and aspect, plants occur in both full sun and light shade. Plants root in rock crevices where humus collects, semi-succulent stems able to gather water and nutrients and survive dry cliff-face situations. Mimicking both the rock habitat and natural plant communities makes for a most attractive and thriving garden display; its eco-mates in the wild are Gasteria croucheri, Crassula perforata and C. perfoliata, Delosperma sp. and Aeollanthus parvifolius. This little mix would suit areas receiving between 800 – 1500 mm of annual, summer rainfall, and where frost if light or absent. Leaves turn rose-pink in autumn as rains dry up and temperatures drop. It is a slow grower with a compact growth form that does well in pots, hanging baskets and rockeries. Prune in late winter to remove weak growth or dead and diseased stems. P. ernstii is pollinated by insects, though fragrant leaves are a possible defense against insect predators. Propagate via seed sown in spring or early summer, or cuttings which can be taken through the year, and root fairly rapidly. South African endemic Provincial distribution: Eastern Cape, KwaZulu-Natal Range: Msikaba River in the northern part of the Eastern Cape to Oribi Gorge in southern KwaZulu-Natal Primary habitat: Forest Classified as: Near Threatened (NT) A species is Near Threatened when available evidence indicates that it nearly meets any of the IUCN criteria for Vulnerable, and is therefore likely to become at risk of extinction in the near future.

Plectranthus ernstii
Plectranthus ernstii