Leucospermum cuneiforme
(Burm.f.) Rourke

Family: Proteaceae (Protea Family)
Common names:
wart-stemmed pincushion (Eng.), luisiesbos (Afr.)

Leucospermum cuneiforme produces its showy pincushions from spring into late summer, bringing welcome colour to the fynbos garden in mid summer.

Description
Leucospermum cuneiforme is usually a stout shrub 1.5-2 m tall but can reach up to 3 m. It has a large persistent, underground rootstock from which many stems arise. The branches at the base of the plant are covered with warts and pustules – this is a unique characteristic and a sure identifier of this species. Leaves are leathery, green, hairless, wedge-shaped (cuneate), with 3-10 apical teeth. The flowerheads are large, oval, 50-90 mm wide. They are produced at the tips of the branches, usually singly, occasionally in groups of 2 or 3. Flower colour varies from locality to locality. Most often the flowerheads are bright yellow ageing to orange but there is some variation: some have orange styles, or red-tipped styles, some age a reddish orange, some a soft orange, some a pinkish orange, many have an attractive bicoloured (yellow and orange) effect. Flowerheads are produced at any time of the year, but the main flowering season is spring to late summer (August-February). Seeds are released about two months after flowering. They are small nuts covered by a soft, fleshy, white skin.

L. cuneiforme mautre flowerhead Warts on L. cuneiforme trunk
L. cuneiforme mautre flowerhead
Warts on L. cuneiforme trunk

Conservation status
Least Concern. Leucospermum cuneiforme is not threatened.

Distribution and habitat
Leucospermum cuneiforme grows on sandstone slopes and flats in the Western Cape and Eastern Cape, from sea level to 1000 m, from Greyton in the Caledon district, along the southern and eastern coastal belt and adjacent mountain ranges, the Riviersonderend, Potberg, Langeberg, Outeniqua and Swartberg Mountains, to just beyond Qolora Mouth in the Kentani district of the Eastern Cape. It is usually found as a few scattered plants. This is the most widespread pincushion. No other pincushion occurs in as wide a range of habitats, vegetation types and climates as Leucospermum cuneiforme. It is found in the winter rainfall area, summer rainfall area and areas were rainfall is evenly spread throughout the year. It grows in fynbos, arid fynbos and on the fringes of the Little Karoo, in grassveld, subtropical coastal dune forest and in the margins of cool temperate evergreen forests. However, it is always found in soils derived from Table Mountain Sandstone, Witteberg Quartzite or stabilised coastal sand of Tertiary origin.

Derivation of name and historical aspects
The genus Leucospermum is named from the Greek leukos meaning white, and sperma seed, referring to the white or light-coloured seeds of many species. This species is named for its wedge shaped leaves, from the Latin cuneus, wedge or wedge-shaped, and folium, leaf.

The genus Leucospermum is a member of the protea family. It consists of 48 species that occur in southern Africa as far north as Zimbabwe, with the majority occurring in the winter rainfall regions of the Western Cape.

Leucospermum cuneiforme was probably first collected by Oldenland, the Dutch East India Company's master gardener at the Cape, in 1689 on an expedition that crossed the Outeniqua Mountains in the vicinity of Attaqua's Kloof. This species was first described by N.L. Burman in 1768 in his Florae Capensis Prodromus from specimens collected by Oldenland (Rourke). Over the past two hundred years a number of additional species, including L. attenuatum and L. ellipticum, were described using variable characteristics such as leaf length, leaf toothing and inflorescence size, but these are now regarded as synonymous with L. cuneiforme (Rourke).

Ecology
Leucospermum cuneiforme is extremely fire resistant. In a fire the above-ground parts are burned, but the woody rootstock survives sending out multiple stems. Plants that have never been burned develop a single main stem and a tree-like habit.

The brightly coloured, unscented flower heads are pollinated by nectar-feeding Sugarbirds and Sunbirds. The birds perch on the flowerhead and probe into the flowerhead in search of nectar, and in so doing their heads and necks come into contact with the pollen presenters and stigmas at the tips of the styles. The flowerheads are also visited by bees and beetles but they don't come into contact with the pollen presenters and thus do not do any pollinating.

The fleshy coating on the seeds is an elaiosome that attracts ants. The seeds fall from the flowerheads when ripe, and ants carry them away to their nests where they consume the elaiosome, but do not harm the seeds. In this way the seeds are dispersed and stored safely underground. This is known as myrmecochory. After a fire, the seeds in the ant nests germinate to regenerate the population. Leucospermum cuneiforme thus employs two strategies to overcome fire: resprouting and myrmecochory.

Uses and cultural aspects
Leucospermum cuneiforme is a decorative and adaptable garden shrub and an excellent cutflower. There are some named cultivars, such as ‘Goldie', and a few Leucospermum cuneiforme hybrids in the trade.

Growing Leucospermum cuneiforme

Leucospermum cuneiforme 'Goldie' flowerheadGrow Leucospermum cuneiforme in a sunny spot in well-drained (sandy), acidic soil where there is free circulation of air. Prune regularly to shape. Like most members of the Protea Family, Leucospermum cuneiforme is adapted to nutrient poor soils and has fine and sensitive roots that cannot cope with strong fertilisers. Feed with diluted liquid fertiliser or low doses of general fertiliser, or slow release fertiliser, and mulch generously and frequently with well-rotted compost. Steer clear of manure. Leucospermum cuneiforme will tolerate summer drought, but performs best with a good weekly watering throughout the year. Leucospermum cuneiforme is also wind tolerant and should survive outdoors in zone 9 (-7 to -1°C; 20 to 30°F).

Leucospermum cuneiforme is ideal for the fynbos garden. It is also suitable for the shrubbery, rockery, slopes and terraces in non-fynbos gardens, and summer-rainfall gardens, provided the soil is well-drained and not alkaline and the site is not humid. It is also suitable for medium to large containers. Leucospermum cuneiforme is relatively fast growing, flowering in its third year from seed. It is long-lived.

Propagate Leucospermum cuneiforme by seed or cuttings. Sow seed in late summer to autumn (March-May). Use a well-drained medium e.g. two parts coarse sand: one part leaf mould or fine-milled pine bark and one part loam. Cover the seeds with coarse, clean sand or fine-milled bark and keep warm and moist. Seeds need alternating cold night and warm day temperatures of 4–10°C to 15–20°C to initiate germination. Such temperatures are typical of autumn in the Western Cape and indicate the start of the rainy season. Germination can be improved if the seeds are soaked in a 1% solution of hydrogen peroxide for 24 hours. This oxygenates the seed and softens and loosens the seed coat, which should be rubbed off. Treatment with Instant Smoke Plus Seed Primer will also enhance germination. Watering the seed tray with a fungicide will prevent fungal disease. Germination occurs in 3-4 weeks and the young seedlings are ready to be potted up as soon as they have developed their first set of true leaves. Use a well-drained, acidic soil mix suitable for fynbos and place them in a lightly shaded, well ventilated area. Seedlings are best planted into the garden when at least one year old.

Take semi-hardwood tip cuttings or heel cuttings from the current season's growth in summer-autumn (Dec-March). Choose vigorous, disease free material. Treat with rooting hormone and place in a well-drained medium and place in a mist unit with bottom heat of 24°C. Good air circulation is required to prevent fungal infection. Rooting occurs in about five weeks, and the rooted cuttings should be hardened off for three weeks before being potted. Use a sandy, well-drained soil mix suitable for fynbos and grow on for at least a year before planting out.

References and further reading

  • Plants of southern Africa: an online checklist. http://posa.sanbi.org
  • Leistner, O.A. (ed.). 2000. Seed plants of southern Africa: families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
  • Rourke, J.P. 1972. Taxonomic studies on Leucospermum R.Br. Journal of South African Botany, Supplementary Volume 8.
  • Rebelo, Tony. 2001. Proteas, A Field Guide to the Proteas of Southern Africa, 2nd Edition. Fernwood Press, Cape Town.
  • Protea Atlas Project. http://protea.worldonline.co.za
  • Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
  • Goldblatt, P. & Manning, J. 2000. Cape Plants, A Conspectus of the Cape Flora of South Africa. Strelitzia 9. National Botanical Institute, Pretoria & Missouri Botanical Garden Press, Missouri.

 

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