As its name implies, the Flats conebush is suited to wetland areas or damp positions in the garden. Plant this shrub in groups to add seasonal colour and use its silver foliage to brighten up your garden plantings.
Leucadendron floridum is a tall bushy shrub that reaches a maximum height of 2 m. Branches are slender and generally upright. Leaves are long and narrow, 27 mm × 5 mm, and covered in silky hairs that produce a shimmering silver effect as the wind blows through the branches.
During spring (September to October) the involucral leaves (the leaves surrounding the bases of flowerheads) turn a vivid yellow illuminating the male and female flowerheads. Up to six involucral leaves per flowerhead curl along the edges and multiple flowerheads are produced on each stem providing a colourful display. Male flowerheads are 14 mm × 11 mm and bright yellow with a faint fruity smell.
Female flowerheads are 13 mm × 9 mm and grow into round silver cones that are up to 26 mm long. The tiny seeds measure only 4.3 mm long and have a ridge running along the surface. They are released in March.
This species looks very similar to Leucadendron uliginosum, however, L. floridum has hairy branches while L. uliginosum has hairless branches.
The flats conebush is listed as Critically Endangered on the Red Data list. Natural populations have been drastically reduced; herbarium records show a subpopulation decrease of over 80% in the past 60 years. Threats that were responsible for this include habitat loss due to urban expansion, agriculture and alien invasive plants. The remaining two populations are threatened by wild flower harvesting, incorrect fire regimes and degradation of habitat.
Plants have been propagated and planted at Kirstenbosch to serve as an ex situ conservation collection. Future restoration plans include re-introducing plants back into suitable habitats.
Distribution and habitat
As its common name infers, this species occurs only on the low-lying Cape Flats from Rondebosch to Kuils River and the Cape Peninsula. It is a wetland species and grows next to streams or in marshy places. In winter its roots are often covered with water.
Derivation of name and historical aspects
The Proteaceae family is large and consists of about 1 400 species worldwide. The genus Leucadendron contains about 83 species, which, apart from a single outlying species and two outlying subspecies, are all confined to the southern and southwestern part of the Western Cape.
The genus name is composed of leucos , meaning white, and dendron , meaning tree. This refers to the iconic silvertree (Leucadendron argenteum ) on which the genus name was based. Early Dutch settlers originally referred to the silvertree as the witteboom or ‘white tree'.
The specific epithet, floridum, means flowering. This alludes to the large sprays of yellow flowerheads produced in spring.
Leucadendron floridum is wind and beetle pollinated. Male plants produce copious amounts of pollen that is carried onto receptive female plants. After pollination, seeds develop within a protective woody cone and are fully ripe after six months. A month later, the cones open and seeds are dropped or carried away by the wind.
Uses and cultural aspects
Plants make good cut foliage—male or female stems can be harvested when not flowering to provide silver foliage. Males stems can be cut when in flower for the bright yellow flowerheads.
Growing Leucadendron floridum
Use the Flats conebush in combination with the following water-loving species: Osmitopsis asteriscoides, Mimetes hirtus, Erica verticillata, Elegia nuda and Zantedeschia aethiopica. The silver foliage will bring light and movement to your garden and make a good filler shrub or informal hedge. This species requires a spot in full sun and should be placed next to a stream or vlei, or watered regularly if planting it into well-drained soil. The Flats conebush is easy to grow and establish in a garden and simply requires an annual scoop of well-decomposed compost. Plants are fast growing and require minimal pruning. It can also be grown in a large container.
P ropagate plants from either cuttings or seed. Sowing seed is the easier method and requires no specialist equipment.
Make cuttings from December to March (summer to autumn). The cuttings should be semi-hardwood, 60–100 mm long, and taken from the current season's growth. Dip the cuttings into a rooting hormone solution or powder and plant them into a medium of 50% polystyrene and 50% finely milled pine bark. Place in a growing house with bottom heat (25ºC). Once the roots are well developed, remove from bottom heat and harden the cuttings off for three weeks. Plant the individual cuttings into small bags and grow on until ready to plant into the garden.
Sow seed in April when the days are warm and the nights start to cool down (late summer to autumn). Dust the seed with a systemic fungicide. Sow on a well-drained medium, firm down and cover with a layer of sand or finely milled bark. Seed can be sown in an open seedbed, or in a seed tray placed in a sunny position. Germination begins after two to three weeks. Once two true leaves have grown, prick the seedlings out into small bags. Place the seedlings in a lightly shaded area with good air circulation. When plants are ±50–100 mm tall, or after one year's growth, they can be planted into the garden.
You can also sow seed directly where you want the plants to grow. Plant, cover lightly with soil, and water.
Once members of the Protea family become diseased they are very difficult to treat, and it is better to prevent disease, rather than try to cure it. Make sure your environmental conditions are correct. This includes getting direct sunlight for most of the day, a sandy well-drained soil, and good air circulation ensuring that the aboveground parts of the plant dry quickly after watering. It is also important to ensure that the soil stays cool in the hot months and that roots are not disturbed by digging. A thick layer of mulch or surrounding planting can be used to keep the soil cool and prevent moisture loss. If any of these factors are out of balance, plants become weak and stressed, and generally become infected with pests or disease.
References and further reading
- Rebelo, A. 2001. Proteas. A field guide to the proteas of southern Africa , edn 2. Fernwood Press, Cape Town .
- Rebelo, A.G., Helme, N.A., Holmes, P.M., Forshaw, C.N., Richardson, S.H., Raimondo, D., Euston-Brown, D.I.W., Victor, J.E., Foden, W., Ebrahim, I., Bomhard, B., Oliver, E.G.H., Johns, A., Van der Venter, J., Van der Walt, R., Von Witt, C., Low, A.B., Paterson-Jones, C., Rourke, J.P., Hitchcock, A.N., Potter, L., Vlok, J.H. & Pillay, D. 2006. Leucadendron floridum R.Br. National Assessment: Red List of South African Plants version 2013.1.
- Vogts, M. 1982. South Africa 's Proteaceae: know them and grow them . Struik, Cape Town.
- Williams, I.J.M. 1972. A revision of the genus Leucadendron (Proteaceae). Contributions from the Bolus Herbarium 3. University of Cape Town .
Kirstenbosch National Botanical Garden