Moraea loubseri

Goldblatt

Family : Iridaceae (Iris family)

 

Moraea loubseri

Moraea loubseri is a beautiful cormous plant from the Cape West Coast with violet-mauve blooms adorned with a prominent black beard. It is one of South Africa's most threatened plant species, but is not very difficult to cultivate.

Description
This slender, winter-growing, summer-dormant geophyte (a plant with subterranean buds produced on specialised storage organs) reaches up to 26 cm high. It grows from a globose corm surrounded by firm, light brown outer tunics and has deciduous roots. It has a solitary linear, bright green leaf 30–60 cm long with a smooth upper surface and a minutely pubescent (hairy) lower surface.

The erect flower stem is minutely pubescent and has two prominent stem nodes and several green stem bracts with light brown tips. The main flower stem and its one or two side branches each produce 1–3 flowers at staggered intervals. The light- to deep violet-mauve flowers are lightly scented and have three large, more or less spathulate (spoon-shaped) outer tepals, each with a triangular, navy blue iridescent spot located just above the prominent black beard. The anthers are situated underneath the three prominent style branches and the pollen is bright orange when ripe. Each style branch has two stigma ‘flaps', situated just above the top of each anther. The cylindrical seed capsule consists of numerous light brown, small angular seeds.

Capsules and seed

Moraea loubseri flowers in spring, from late August to mid-September. It belongs to a group of species popularly known as ‘peacock moraeas', whose members have relatively long-lasting blooms (3 days) with brightly coloured, large outer tepals with iridescent spots. Many peacock moraeas are threatened, including M. aristata , M. gigandra, M. tulbaghensis and M. villosa. Moraea calcicola, another threatened species from the Cape West Coast, is superficially similar to M. loubseri in its mauvish-blue flowers but it is a taller plant with larger, orbicular (spherical) outer tepals, and it flowers later in the season, from mid- to late September.

Conservation status
Moraea loubseri is a protected species. It is also a highly threatened species and until recently, it was thought that it may have become extinct in the wild, as no living specimens had been recorded for a number of years. Following the recent sighting of two flowering specimens (see history below) its conservation status has been re-assessed as Critically Endangered. Seeds collected from hand-pollinated, cultivated specimens in the bulb nursery at Kirstenbosch are in long-term cold storage in the Millenium Seed Bank at Wakehurst Place in Sussex, United Kingdom. Efforts are currently under way to bolster the remaining individuals in the wild by the introduction of additional material from the bulb nursery at Kirstenbosch.

Distribution and habitat
Moraea loubseri is endemic to a single site near the resort town of Langebaan on the Cape West Coast. It is confined to sandy, granite-derived soil on a granite dome in Saldanha Granite Strandveld, a vegetation type only encountered from St Helena Bay in the north to Langebaan in the south and its adjacent peninsula. The plants occur as solitary individuals amongst low-growing scrubby growth which includes a rich succulent and geophyte flora.

Derivation of name and historical aspects
In 1758 the Scottish horticulturist and botanist Philip Miller established the genus Morea in honour of Robert More of Shropshire. Carolus Linnaeus later altered its spelling to Moraea to associate the name with his father-in-law, J. Moraeus, a Swedish physician.

The South African bulbgrower Johan Loubser discovered this species in 1973, and in 1977 it was named in his honour by Dr Peter Goldblatt in the botanical magazine Flowering Plants of Africa . The plant had been plentiful up until the early 1970's but thereafter its numbers declined drastically due to the loss of most of its habitat as a result of quarrying for ballast, for use in the construction of a new iron ore harbour terminal in adjacent Saldanha Bay. In 1980 it was declared extinct in the South African National Scientific Programmes Report no. 45, but in the spring of 1982, Johan Loubser re-visited the original site and reported some 200 plants in flower; it would appear that certain visitors to the site may not have known precisely where the plants grew and not finding any in flower, considered it extinct. Mysteriously, very few plants were sighted in the ensuing two decades, and between 2004 and 2008, none at all were reported following surveys by members of the Custodians of Rare and Endangered Wildflowers (CREW), but in September 2011, the botanist Rupert Koopman located two flowering specimens.

Moraea loubseri was initially cultivated by Johan Loubser shortly after its discovery, and subsequently, corms and seeds were donated to the bulb collection in the nursery at Kirstenbosch. Here the plants thrived and multiplied to the extent that in 1980 I was able to provide 135 packets of surplus seeds for distribution to members of the Botanical Society of South Africa, and seeds were subsequently distributed to members on numerous occasions. As a result, M. loubseri is now well established in bulb collections in South Africa and abroad, including Australia, France, New Zealand, the UK and the USA.

 

The most important South African Moraea species in ornamental horticulture is the sturdy, large yellow-flowered M. huttonii which is often grown outdoors in the United Kingdom. It is an evergreen species with a wide distribution from the Eastern Cape to Mpumalanga, and certain of its forms are frost hardy.

Ecology
Moraea loubseri is adapted to a cycle of rapid vegetative growth during the cool winter months, flowering in early spring, and desiccation of the aerial parts being followed by complete dormancy of the corm during the hot summer. The plants are so rare that actual pollinator sightings have not yet been made, and there is a poss ibility the pollinator no longer exists at the type locality. However, it can be inferred from pollinators of other members of the ‘peacock moraea' alliance that hopliine beetles (family Scarabaeidae) were the probable pollinators. When ripe, the cylindrical seed capsules split from the apex downwards and the seeds are dispersed locally by the shaking action of wind.

Uses and cultural aspects
Moraea loubseri is used to a limited extent as a container subject in ornamental horticulture by specialist bulb growers. It has no traditional, economic or medicinal uses.

Cluster in flower

Growing Moraea loubseri

Despite its scarcity in the wild, Moraea loubseri responds well to cultivation. The plants are most suitably grown in deep pots with a diameter of 25 cm, and a well drained acid or alkaline growing medium can be used. In the Kirstenbosch Bulb Nursery it is grown in a mixture of equal parts of coarse industrial (silica) sand and finely milled bark, with a 30 mm layer of well-rotted compost placed at the base of the container over the drainage chips. Mature corms are planted 20 mm deep in autumn. An initial heavy drench is provided in mid-autumn, followed by twice-weekly applications once the leaves appear and thereafter throughout the winter growing period. It is important to maintain sufficient moisture during flower bud formation to prevent plants from entering dormancy prematurely. Similarly, the plants require heavy drenching during the flowering and fruiting periods in order to perform optimally.

The plants respond well to liquid or slow-release fertilizer applications with high potassium but low nitrogen content. Once the leaves start turning yellow in early summer, watering must cease until the following autumn. The plants are not suited to general garden cultivation owing to their need for a completely dry summer, and due to the corms falling prey to mole rats and porcupines; in areas not plagued by these animals, they can be grown in dedicated rock garden pockets kept dry in summer. M. loubseri is half-hardy and able to withstand temperatures down to 0°C for short periods, but in cold winter climates it needs to be grown in the cool greenhouse. When maintaining a large bulb collection, it is important to harvest the ripe capsules of M. loubseri in time, immediately after they have started to split, as the seeds are released in gusts of wind and readily colonise adjacent pots.

The corms are fairly long-lived, lasting about 8–10 years under ideal conditions. To obtain pure seed, it is necessary to isolate and hand-pollinate the flowers. Pollen can be collected by dabbing a water paint brush over the ripe anthers, which are located directly beneath the style branches. Pollen is ready for collection once it has turned bright orange and become somewhat sticky, then, moving to a flower of a different clone, lightly brush the two stigma ‘flaps' situated just above the top of each anther. Seed sets readily after successful fertilization and 50 seeds or more can be harvested from a single capsule. Seeds are sown in autumn in the same medium recommended for adult corms. Fresh seeds germinate readily within 3 weeks and in ideal conditions, flowering can occur in the second year, but more usually this takes place in the third spring season. Excellent viability of fresh seeds is maintained when stored at room temperature for 6 months following harvesting and sowing in the immediately ensuing autumn, but viability decreases markedly thereafter. Long-term storage of seeds is excellent at 6–7°C, and this can easily be achieved by the home-grower using the vegetable compartment of a fridge. This species can also be propagated by separation of corm offsets in early autumn.

The leaves, stems, flower buds and developing capsules are susceptible to attack by aphids, and the leaf undersides to red spider mites as temperatures rise in spring.

References and further reading

  • DUNCAN, G.D. 1981. Moraea loubseri Goldbl. – saved through cultivation. Veld
  • & Flora 67(1): 18–19.
  • DUNCAN, G.D. 1997. Moraeas of the Western Cape. Veld & Flora 83(2): 42–44.
  • DUNCAN, G.D. 2010. Grow bulbs . Kirstenbosch Gardening Series. South African National Biodiversity Institute, Cape Town.
  • DUNCAN, G.D. 2011. Moraea loubseri . Curtis's Botanical Magazine 28: 317–323.
  • EBRAHIM, I., VON WITT, C. & COHEN, C. 2005. Peacocks, ploughs and porcupines. Veld & Flora 91(4): 185–187.
  • GEARY-COOKE, R. 1983. Moraea loubseri is not extinct. Veld & Flora 69(4): 144.
  • GOLDBLATT, P. 1977. Moraea loubseri . Flowering Plants of Africa 44: t. 1724.
  • GOLDBLATT, P. 1986. The moraeas of southern Africa. Annals of Kirstenbosch Botanic Gardens 14. National Botanic Gardens, Cape Town.
  • KOOPMAN, R., VON STADEN, L., SNIJMAN, D. & VON WITT, C. 2011. Moraea loubseri Goldblatt. National Assessment: Red List of South African Plants version 2012.1 Accessed on 2012/06/07.
  • MUCINA, L. & RUTHERFORD, M.C. 2006. The vegetation of South Africa, Lesotho and Swaziland . Strelitzia 19 . South African National Biodiversity Institute, Pretoria.  

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Graham Duncan (text & images)

Kirstenbosch National Botanical Garden

October 2012

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