Diastella divaricata subsp. divaricata
Diastella divaricata (P.J.Bergius) Rourke subsp. divaricata
Common names: Peninsula silkypuff
A sprawling, creeping, rounded shrub dotted with small, pink inflorescences, that gives the best year-round display in a fynbos garden, and is a champion creeper for hanging baskets and pots in full sun.
Diastella divaricata subsp. divaricata is a small, evergreen, fynbos shrub, that grows about 0.5 m high, and sprawling up to 3 m in diameter. The shrub has creeping stems that hang down when planted in containers or hanging baskets and spread widely when growing in the ground. It grows from a single stem that produces the many stems that sprawl out and makes a dense growth. The old stem remains firm, whereas the new shoots grow slightly up, sprawling and hanging. Lower stems often grow flat on the ground. The old stems become brown and hairless, whereas the new stems are soft and hairy. It has a short, oval or round leaf of 2–10 mm long and 2–7 mm wide. The leaves are alternate, hairy, with reddish margins on the new leaves, but this reddish margin disappears when the leaves have matured.
Diastella divaricata subsp. divaricata produces small, pink flowerheads. The involucral bracts and perianths are both pink and become papery with age (never becoming woody). The styles are 8–10 mm long and exserted 2 mm above the ovary . Peninsula silkypuff flowers year round, with a peak in spring, from August to September. Each flower occasionally makes one nut-like seed, and releases the fruit 1–2 months after flowering. The fruit is egg-shaped, 4–6 mm long, greyish or white, and is hardly seen on cultivated plants.
Diastella divaricata subsp. divaricata is very similar to D. divaricata subsp. montana, the mountain silkypuff. However, the two subspecies differ by their geographical distribution, in leaf size and shape and the pubescence of the base of the styles. Subsp. montana has long, narrow, lanceolate to elliptic leaves, 10–18 mm long and 1–7 mm wide, and occurs from the Wemmershoek Mountains to Villiersdorp, western Riviersonderend Mountains, Hottentots-Holland, Greenland, Kleinmond and Kleinrivier Mountains, growing on the southern, sandstone slopes, in a cool and moist environment.
According to the Red List of South African plants, checked in April 2017, Diastella divaricata subsp. divaricata is assessed Rare. It is restricted to the Cape Peninsula, but large subpopulations are conserved and protected in the Table Mountain National Park, so it is not regarded as threatened.
Distribution and habitat
Diastella divaricata subsp. divaricata is endemic to the Cape Peninsula, distributed from the Steenberg Plateau, southwards throught Silvermine to Cape Point. A single herbarium specimen is recorded from the golf course at Mowbray, but this has not been seen again in living memory (Rebelo 2000). Most of the population occurs on the low flats, with a few populations occurring at 600 m elevation.
Derivation of name and historical aspects
Diastella is derived from the Greek word diastellein, which means ‘to separate’. This refers to the soft, silky-haired perianth segments which are free to the base. Divaricata is also a Greek word meaning ‘branched’. This refers to the growth habit of the plant.
Diastella is one of 14 genera of the Proteaceae family. The genus Diastella is endemic to the Cape Floristic Region. It is a small genus that comprises of 7 species. All are shrublets and almost all species are threatened. There are the northern silkypuffs, D. parilis [Critically Endangered] and D. myrtifolia [Critically Endangered] and the southern silkypuffs, D. buekii [Critically Endangered], D. fraterna [Rare], D. proteoides [Critically Endangered], D. thymelaeoides subsp. meridiana [Vulnerable], D. thymelaeoides subsp. thymelaeoides [Near Threatened], D. divaricata subsp. montana [Vulnerable] and this subspecies. The southern silkypuffs do not produce nectar, whereas the northern silkypuffs have floral nectaries.
Diastella divaricata subsp. divaricata produces smooth, nut-like seeds which have an elaiosome. The seeds are taken by ants and stored underground in their nests. The ants feed on the elaiosome, but leave the seed unharmed.
Usually one fruit develops in each head and drops to the ground when matured, within a period of 2 months, and will germinate the following autumn if not removed by ants or destroyed by rodents. No records were made for Peninsula silkypuff pollinators, though it is believed to be pollen-collecting bees.
Male and female parts are in the same flower (bi-sexual). The ‘flower’ is an inflorescence made up of many flowers in one head.
Peninsula silkypuff is killed by fire and regenerates by seed (reseeder). Some plants may survive fires by forming dense mats which only burn at their edges.
Diastella divaricata subsp. divaricata is an excellent plant when cultivated in a container or the garden, preferably in a rockery, retaining wall or fynbos garden. Peninsula silkypuff has a naturally cascading habit and develops a wonderful rounded shape.
Growing Diastella divaricata subsp. divaricata
Diastella divaricata subsp. divaricata is easily propagated by cuttings and seed. Select the cuttings from healthy plants. Take heel or tip cuttings of semi-hardwood 30–70 mm long in autumn and spring. Treat with a rooting hormone to stimulate rooting. Dip the cutting in the rooting hormone for at least 5 seconds. Place your cuttings in a well-drained and aerated medium of 70% perlite and 30% fine bark or use coarse sand and finely milled, pine bark sowing medium. Insert the cuttings in the multitrays with a space between each cutting to allow air circulation, and place them on the heated benches of 25ºC under intermittent mist. Regularly treat the cuttings with fungicide to prevent fungal infection. Remove the dead leaves and wilting cuttings until your cuttings are rooted. Move the rooted cuttings to the hardening-off house for about 2 weeks and transfer the cuttings into small nursery plastic bags using a fynbos mixture of well-drained, acidic medium of fine bark, coarse sand and finely milled, pine bark.
The seeds are not easy and time-consuming to collect, therefore most cultivation is done by cuttings. Seed must be treated with a fungicide to prevent pre-and post-emergence damping-off. Treat your seed with a dusting systemic fungicide containing the active ingredient, metalaxyl. The seed is sown in late summer or early autumn. Use a well-aerated and well-drained potting or sowing medium and treat with smoke. Lay the seed trays under the plastic tent and the pipe, in the smoke of burning, fynbos plant material. Smoke-plus seed primer packets are also available to use and can be ordered from Kirstenbosch National Botanical Garden Seedroom.
Place the seedlings or cuttings under the shade net in the nursery until they are ready to be planted into the garden, after a period of 2 to 3 years. Net shade reduces the direct sun which can dry out the soil in the plastic bags and can also prevent scorch. Diastella divaricata subsp. divaricata is a water-wise shrub that will need to be watered for about 2 to 3 years, to establish the roots. Plant the seedlings in sandy acidic soil with between 5–7 pH levels.
Keep the soil moist during the hot dry season by mulching your bed about 5 mm thick. The mulch will keep the roots cool, keep moisture to the soil and reduce the growth of weeds. Chipping mulch is recommended, as they break down very slowly and also releases small amounts of nutrients to the plant. Diastella dicaricata subsp. divaricata does need pruning to keep the rounded shape and nice cascade in a container.
Peninsula silkypuff is not affected by other serious insect pests, however, seedlings are highly susceptible to pre- and post-emergence damping-off fungi.
Diastella divaricata subsp. divaricata can be grafted on the scion of the hybrid ‘Veld Fire’, a cross between Leucospermum glabrum and L. conocarpodendron subsp. conocarpodendron. The grafted plant can sustain the longevity and resistance of the plant in the garden.
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- Brown, N.A.C. & Duncan, G.D. 2006. Grow fynbos plants. Kirstenbosch Gardening Series. South African National Biodiversity Institute, Cape Town.
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- Paterson-Jones, C. 2000. The protea family in southern Africa. Struik Publishers, Cape Town
- Protea Atlas Project: Diastella. http://www.proteaatlas.org.za/Protea_Atlas_Diastella.pdf. Accessed on 2017/03/29.
- Protea Atlas Project: Meanings of scientific names. http://www.proteaatlas.org.za/meanings.htm. Accessed on 2017/03/29.
- Rebelo, A.G. et al. 2005. Diastella divaricata (P.J.Bergius) Rourke subsp. divaricata. National Assessment: Red List of South African plants version 2017.1. Accessed on 2017/03/29.
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- Rebelo, A.G. 2001. Proteas. A field guide to the proteas of southern Africa, edn 2. Fernwood Press, Vlaeberg, Cape Town.
- Rourke, J. P., 1976. A revision of Diastella (Proteaceae). Journal of South African Botany 42(3): 185–210.
- Vogts, M. 1982. South African's Proteaceae: know them and grow them. Struik, Cape Town.
Kirstenbosch National Botanical Garden
Plant Type: Shrub
SA Distribution: Western Cape
Soil type: Sandy
Flowering season: Spring, Sporadic/All year
Flower colour: Pink
Aspect: Full Sun
Gardening skill: Average