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Products > Plectranthus argentifolius
Plectranthus argentifolius - Somalian Spur Flower
Image of Plectranthus argentifolius
[2nd Image]
Habit and Cultural Information
Category: Shrub
Family: Lamiaceae (Labiatae) (Mints)
Origin: Somalia (Africa)
Evergreen: Yes
Flower Color: Blue
Bloomtime: Spring
Synonyms: [Coleus argentifolius, Plectranthus coerulescens]
Height: <1 foot
Width: 2-3 feet
Exposure: Sun or Shade
Summer Dry: Yes
Irrigation (H2O Info): Low Water Needs
Winter Hardiness: 30-32 F
Plectranthus argentifolius (Somalian Spur Flower) - A small low growing compact subshrub to about 1 foot tall spreading to 2-3 feet wide with stems that can drape over a wall or raised planter. It has semi-succulent blue-green leaves whose margins are entire or very finely toothed and in spring has showy pale-blue boat-shaped flowers on spaced stem circling clusters, called verticillasters, that cover the plant in profusion.

Plant in full sun to a brightly lit shade in a well-drained soil and irrigate occasionally to very little. We have not tested this plant for hardiness below 32F but most Plectranthus, even ones that come from colder climates than this, are a bit sensitive to a frost and one might want to protect this little jewel.

Plectranthus argentifolius is found growing in juniper and acacia scrubland on limestone or gypsum rocks, stony plains and slopes from 4,600 to 7,200 feet in elevation at two locations separated by the Gulf of Aden, one near Ceerigaabo in the Sanaag Region of Somalia and the other in the Taiz Province in Yemen.

The name for the genus comes from the Greek words 'plektron' meaning a "spur" and 'anthos' meaning "flower" in reference to the spur that is found at the base of the corolla tube of the type species Plectranthus fruticosus. The specific epithet comes from the Latin words 'argentum' meaning "silver" and? 'folium' meaning "leaf" in reference to the silvery gray leaves.

We originally received this plant in 2012 as Plectranthus coerulescens, a plant reportedly collected on limestone rocks at Harar in Ethiopia, but the holotype of Plectranthus coerulescens (as Coleus coerulescens) was destroyed in Berlin during World War II, and the isotype consists of only fragments and a drawing of the inflorescence, so the validity of the name has long been uncertain with some references combining this species with the similar Plectranthus argentifolius that was described from Somalia and Yemen. R.H Williamse in 1985 redescribed Plectranthus coerulescens from cultivated material from a Dutch botanic garden to include both the Somalian plant previously known as P. argentifolius and the Ethiopian plant, noting that Plectranthus argentifolius has pedicels hardly more than 6mm long, which flowers of this plant exceeds and is not known from Ethiopia. To make matters even more confusing, this name is sometimes listed as a synonym for Plectranthus barbatus var. barbatus, a far different plant.

Ernst Van Jaarsveld, retired curator of the Kirstenbosch Conservatory in South Africa and author of The South African Plectranthus confirmed in 2013 that he thought this plant rightly should be called Plectranthus argentifolius. In 2018 Alan Paton, Head of Collections at the Royal Botanic Garden Kew, did a revision of Plectranthus and related plants (Paton, A.; Mwanyambo, M. & Culham, A. (2018). "Phylogenetic study of Plectranthus, Coleus and allies (Lamiaceae): Taxonomy, distribution and medicinal use". Botanical Journal of the Linnean Society. 188 (4): 355376.). The new names were further clarified in 2019 in an article he wrote titled "Nomenclatural changes in Coleus and Plectranthus (Lamiaceae): a tale of more than two genera" in PhytoKeys (PhytoKeys 129 (2019) which transferred many of the Plectranthus species, including this species into the genus Coleus, making the valid name of this plant Coleus argentifolius. The name Coleus comes from the Greek word 'koleus', meaning a sheath, in reference to the manner in which the stamens are enclosed.

We had long retained the older name Plectranthus coerulescens that we received this plant as, but in November 2020 retired Huntington Botanic Garden horticulturalist John MacGregor, who has long had an interest in Coleus and Plectranthus and is moderator of the Facebook group Planet Plectranthus/Coleus, contacted us and suggested that we really should be listing this plant by its valid name, Coleus argentifolius (Ryding) A.J.Paton comb. nov. and not as Plectranthus coerulescens. So not to confuse our customers too much we have only changed the specific epithet in our listing to "argentifolius", but for now continue to list this plant as a Plectranthus species until such time as these names get better recognized by our customers. We received this great plant from our friend John Bleck and first offered it for sale in 2014. 

This information about Plectranthus argentifolius displayed is based on research conducted in our horticultural library and from reliable online resources. We also will relate observations made about it as it grows in our nursery gardens and other gardens we have visited, as well how the crops have performed in containers in our nursery field. We will also incorporate comments that we receive from others and we welcome hearing from anyone with additional information, particularly if they can share any cultural information that would aid others in growing it.