Primula verticillata (yellow primrose)
An attractive perennial with elegant yellow flowers, Primula verticillata is native to north-east Africa and south-west Arabia, and is one of the parents of the Kew primrose (‘P. kewensis’).
About this species
Primula verticillata was found by Peter Forsskål (1732-1763), a Finnish plant collector (and student of Swedish botanist Carl Linnaeus) who visited Arabia in 1762. The specific epithet verticillata (from the Latin verticillatus, meaning whorled) refers to the flowers, which are in rings on the stem. In addition to P. verticillata subsp. verticillata there are two other subspecies. P. verticillata subsp. simensis (the Abyssinian primrose, sometimes treated as a separate species, P. simensis) occurs in the Ethiopian Highlands. It is a more compact plant with paler grey leaves than those of P. verticillata subsp. verticillata. The much rarer P. verticillata subsp. boveana (sometimes referred to as P. boveana) is an even smaller plant, restricted to Mount Sinai (Egypt). It was named in honour of Nicolas Bové (1812-1841), one of the first botanists to study the flora of the Sinai Peninsula.
Geography & Distribution
Native to north-east Africa and south-west Arabia (including Saudi Arabia, the Yemen Republic, Ethiopia and Somalia), where it occurs on damp limestone hills and damp shady cliffs. In the Simien Mountains of Ethiopia it is found in alpine grassland in the alpine zone from 3,800 m above sea level, along with giant lobelia (Lobelia rhynchopetalum), everlastings (Helichrysum species), and scattered tree heather (Erica arborea).
Primula verticillata is a perennial with stems up to 70 cm long. The greyish-green leaves are spear-shaped, up to 30 cm long in a rosette. P. verticillata bears several whorls of long-tubed, golden-yellow, scented flowers in late spring. Reproduction is by seed.
Illustration from Curtis's Botanical Magazine
Watercolour illustration of Primula verticillata by W.J. Hooker(1828), taken from Curtis's Botanical Magazine (Image: RBG Kew)
Curtis’s Botanical Magazine(Editor: Martyn Rix) provides an international forum of particular interest to botanists and horticulturists, plant ecologists and those with a special interest in botanical illustration.
Now well over two hundred years old, the Magazine is the longest running botanical periodical featuring colour illustrations of plants. Each four-part volume contains 24 plant portraits reproduced from watercolour originals by leading international botanical artists. Detailed but accessible articles combine horticultural and botanical information, history, conservation and economic uses of the plants described.
Published for the Royal Botanic Gardens, Kew by Wiley-Blackwell Publishing.
See the Wiley-Blackwell Subscription Information page for rates (for both print and online).
Threats & Conservation
Primula verticillata (Image: Richard Wilford)
Primula verticillata subspecies boveana is known only from Mount Sinai (Egypt), an area subject to frequent drought, placing its wild population under threat. Since it is separated from the other subspecies by vast areas of desert, where primulas would not survive, it seems likely that P. verticillata subsp. boveana and its closest relatives migrated to the Arabian Peninsula and north-east Africa from the Himalaya (where there are many more species of Primula) when the climate was wetter. If Egypt becomes drier in the future as a result of climate change, the wild population of P. verticillata subsp. boveana could be in danger.
In Ethiopia, Primula verticillata is protected within the Simien National Park and World Heritage Site.
In Saudi Arabia, the ground rhizome of Primula verticillata is used in traditional ethnoveterinary medicine for treating fever in camels and as a general tonic. P. verticillata is cultivated as an ornamental and is suitable for growing in a cool greenhouse in temperate climates.
Millennium Seed Bank: Seed storage
Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.
Number of seed collections stored in the Millennium Seed Bank: Two.
Germination testing: 100 % germination was achieved on a 1% agar medium, at a temperature of 20°C, on a cycle of 8 hours daylight/16 hours darkness.
Primula verticillata should be grown in well-drained, leafy soil and be shaded from hot summer sun. It needs winter protection in northern Europe and makes a good, early-flowering (March) species for the cool greenhouse. It will not tolerate temperatures more than a couple of degrees below freezing.
This species at Kew
Primula verticillata (Image: RBG Kew)
Primula verticillata can be seen growing in the Davies Alpine House at Kew; these plants were grown from seed collected in the Yemen in 1975 by Kew botanist Nigel Hepper (now retired).
Pressed and dried specimens of P. verticillata are held in Kew’s Herbarium, where they are available to researchers by appointment. The details of one of these specimens, including an image, can be seen on-line in the Herbarium Catalogue.
The Kew primrose
The Kew primrose (known as ‘Primula kewensis’) is a fertile interspecific hybrid derived from a cross between Primula floribunda (from the Himalaya) and Primula verticillata. This hybrid (Primula x kewensis) first occurred by chance in the glasshouses at Kew in the late 1890s. It has ovoid leaves up to 20 cm long, which are covered in greyish-white farina (a mealy or powdery covering), and has bright yellow, fragrant flowers. The type form of the hybrid was awarded a First Class Certificate by the Royal Horticultural Society when it was exhibited in 1900. In order to verify the supposition that the parents were indeed P. floribunda and P. verticillata the cross was repeated artificially using P. verticillata as the pollen parent. The resultant offspring were all sterile with ‘thrum’-type flowers (with the stamens protruding from the flower), so the stock had to be propagated by cuttings or division. Most of the sterile stock was acquired by the famous Veitch and Sons nursery in 1901. Around 1905, a single ‘pin’-eyed flower (one with the style more prominent) was noticed amongst the nursery stock. This flower was fertilised with pollen from a ‘thrum’-eyed flower and viable seed was set. Subsequently, the cross between the two parents has been repeated at various times, and various forms selected. Genetically, ‘Primula kewensis’ is an allopolyploid (having more than two sets of haploid chromosomes inherited from different species). The Kew primrose is available from commercial nurseries and is suitable for a cool greenhouse in temperate climates. At Kew it can be seen growing in the Temperate House and is also grown in the Arboretum Nursery.
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