As winter begins to loosen its grip in the Cape, spring is heralded by a magnificent profusion of sunshine yellow as Erica nana comes into flower. Much more than “just another erica” Erica nana offers its collector an avenue into the wonderful world of Fynbos ecology and a chance to slow down and pay attention to the intricate details of the natural world around us.
Erica nana is a low-growing, sprawling, woody shrub attaining a diameter of 1 m and an average height of 500 mm. E. nana is highly floriferous, the flowers often completely covering the neat and compact shrublet from September to October. The branches are described as divaricate (spread widely), flexuous (winding from side to side) and ridged. Leaves are 4-nate (4 leaves arranged in a ring around the stem), 4–8 mm long, erect and linear. The flowers are 3- or 4-nate (consisting of 3 or 4 parts) and are found at the ends of short branches. Sepals (modified leaves that surround and protect the flower while in bud) are keeled. Upon opening, the tubular, 20 mm long corolla (main visible part of the flower, consisting of four joined petals) is greenish yellow but soon turns to a bright yellow producing a spectacular sight. The corolla lobes are slightly cup-shaped. Anthers have awns (appendages at the base of the anther).
As South Africans we are custodians of the world's richest temperate flora. We can say this confidently because of the 370 000 species of mosses, ferns and seed plants currently estimated to exist on our planet 20 456 species are recorded here. Of this number 65% (13 256 species) occur nowhere else in the world. This is astounding when you consider that South Africa only accounts for 2.5% of the world's land surface! So, what we have is precious.
One of the many species exemplifying this precious condition would be Erica nana. According to the Red List of South African Plants (Raimondo et al. 2009) E. nana is listed as Vulnerable (VU). Found nowhere else in the world except on the high slopes of the Hottentots Holland Mountains and in the cracks and crevices above Kogel Bay, this species is naturally rare. This condition has been exacerbated, however, by too frequent fires, the construction of Sir Lowry's Pass and over-exploitation by wildflower harvesters. "Here today" can so easily become "gone tomorrow"! Luckily, many of these activities have stopped, and this South African jewel is blessed with a number of characteristics which make it a worthy horticultural subject (Hitchcock 1990).
Distribution and habitat
The genus Erica contains a total of 860 species and these may be found growing from the southernmost tip of Africa to the northernmost tip of Norway. Of the 860 species South Africa is home to 760, with the highest concentration occurring in the Caledon district, where more than 235 species occur within 4500 square kilometers (Schumann et al. 1992). Erica nana grows naturally at high altitudes on the rocks and cliff faces of the Hottentots Holland Mountains at three specific localities only. The cold wet winters and warm dry summers of the Mediterranean type climate characterise the area but the change from one season to the next is mild due to the moderating effects of the dominant ocean winds coming off the South Atlantic Ocean.
Derivation of the name and historical aspects
What is an erica? In the field, it is said, that the one major character to look for are the small, narrow, folded leaves, described as ‘ericoid'. Dating back to the time of the ancient Greek civilization when Theophrastus and Pliny walked the earth, you would have heard them use the term ‘erike' as they described the heath-like shrubs around them. In 458 BC Aeschylus wrote a play called Agamemnon in which the fall of Troy is told to have been signaled from the mountain tops by the light of the fires of dried ereika. Ereiko means to break, which may describe the plants brittle stems that would easily split with a little force. A number of references, though, suggest that ereiko describes the plants ability to break up bladder stones, once an infusion of the leaves was ingested (Hyam & Pankhurst 1995). Ericaceae (Heath family) is a worldwide floral family consisting of about 116 genera and approximately 3000 species of shrubs, climbers, herbs and even a few trees. Erica is the largest genus within this family. Nana comes from the Latin nanus, which means dwarf and describes Erica nana's low growth habit.
Fynbos ecology is absolutely mind blowing! Nutrient poor soils, hot dry summers alternating with cool wet winters, recurrent fires and an elaborate web of animal-plant interactions have created over the millennia, an ancient vegetation type with a complex ecology, a delicate balance and an explosive diversity – our famous and unique fynbos. Ericas are one of the four main constituents of this vegetation type – bulbs, proteas and restios being the other three. Erica nana captures much of this ecological intrigue, particularly when you consider where it grows. Adapted to survive at high altitudes on rocks and cliff faces on the slopes of the Hottentots Holland Mountains and Kogelberg...nowhere else in the world!
Growing on vertical rocky cliffs means that species like Erica nana are relatively safe from being browsed or from being trampled underfoot. Erica nana therefore does not waste precious resources on defence but rather must find a way to cope with the effects of gravity, high water runoff, excessive exposure to solar radiation and strong winds, rapid temperature changes and a very limited amount of soil. Erica nana's short stature and compact habit is no surprise then, because staying low means it can avoid high winds and stay warmer, as any heat from the earth is immediately captured in and amongst its flexuous branches. Erica nana is also evergreen. This means that it photosynthesises whenever growing conditions are suitable. It can thus take full advantage of short growing seasons and doesn't need to develop a new set of leaves at the start of each growing season. The soil on the cliffs is often acidic, thin to non-existent and offers limited nutrients. The heath family in general has a well adapted root system equipped to penetrate hard surfaces, withstand a certain amount of exposure and extract even the most minuscule amount of nutrients from the nutrient-deficient substrate.
Growing Erica nana
Simply because they're absolutely stunning or perhaps to help preserve some of the many species threatened with extinction you have decided to grow some ericas. Growing ericas is not difficult in the winter rainfall region because the natural climate and the soils of this area allow for a great variety of species to be grown successfully. Of the 760 species of Erica, 50 have good garden potential but it is still up to you to carefully consider the growing requirements of each species and the particular conditions present in your garden. In the summer rainfall region the rule of thumb is to ensure that the species you ‘have your eyes on' is known to be suitable for the conditions ruling there. Ericas grow well in pots, so, when a sunny spot with good air circulation and no cold winds is difficult to find find an attractive container and move the plant around as conditions change.
Like all erica species Erica nana may be grown from seed or cuttings, however, cuttings are easier and faster to grow and produce plants that are far more robust. Seedlings grown from cuttings can also be transplanted within six months, as opposed to a year for seed-grown plants, and they will flower a year earlier (Schumann et al. 1992). Considering the rarity of this species, though, seeds are likely to be your only option for propagation – regard it as a challenge!
Seed can be purchased from a number of sources, one of which is Kirstenbosch National Botanical Garden. If you already have a plant, you should harvest seed just as the flowers start to fall naturally. The old flowers should be dried and then rubbed through a sieve. Sow seed between March and May in a seed tray not less than 100 mm deep. Seed may be soaked in a commercial smoke seed primer for 24 hours before sowing and then dried off. The seed tray, evenly filled with the well-drained acidic medium, should be well watered with a fine rose prior to sowing. Sow seed evenly and cover with a fine layer of the sieved growing medium. Water gently with a fine rose and keep out of direct sunlight and rain in an area with good air circulation. Germination occurs within 1–2 months. When the seedlings are about 10 mm tall place the tray under light shade conditions until October–December. When 20–50 mm tall, prick out and plant in a fynbos potting medium (seven parts sand and three parts sifted humus). Place in light shade and water well. Once established, shading is not required.
Take 40–50 mm cuttings from semi-hard wood two months after flowering from healthy mature plants. Heel and stem cuttings work best. Remove the leaves from the lower 1/3 of the cutting, dip into a rooting hormone and place into a tray filled with 50% peat, or crushed pine bark, and 50% polystyrene. Bottom heating between 22–24°C is applied, and once cuttings are rooted they are potted up into ½ liter plastic bags. Young cuttings must be watered well and kept under shade for a month, after which they are placed into full sun. After 3–4 months plant out.
Soil is a sensitive issue. The potting medium should be well drained and acidic, containing no manure, and have low levels of phosphate. A well-drained sandy loam with a pH between 5 and 5.5, containing about 50% humus is ideal (Brown et al. 2006). Ericas grow better when planted close together with other fynbos plants to form dense stands that cover the ground. They grow particularly well in rockeries or sloping ground but level areas will work as well. Before planting dig in some well rotted pine bark.
References and further reading
- Baker, H.A. & Oliver, E.G.H. 1967. Ericas in Southern Africa. Purnell & Sons, Cape Town.
- Brown, N.A.C. & Duncan, G.D. 2006. Grow fynbos plants. Kirstenbosch Gardening Series. South African National Biodiversity Institute, Cape Town.
- Hyam, R. & Pankhurst, R. 1995. Plants and their names. Oxford University Press, New York
- Jackson, W.P.U. 1990. Origins and meanings of South African plant genera. University of Cape TownPrinting Department.
- Oliver, T. (E.G.H.) & Oliver, I. 2000. Ericas of the Cape Peninsula. National Botanical Institute, Cape Town.
- Schum ann, D., Kirsten, G. & Oliver, E.G.H. 1992. Ericas of South Africa. Fernwood Press, Vlaeberg.