Linzia glabra Steetz sens.lat.
Common names: wild heliotrope
Linzia glabra is a strong-growing, herbaceous perennial that flowers throughout the summer, producing masses of flowers that look like little mauve paintbrushes, at the tips of many upright stems. It was previously called Vernonia glabra.
From a woody rootstock, tall, robust stems shoot stiff and upright, branching sparingly to about 1.2 m high. Smooth to the touch, the leaves are bright green, linear (long and narrow), 60-120 x 15-25 mm, with a serrated edge and a prominent, light yellow, central vein. They alternate with each other along the stems, getting smaller towards the tip.
The flowers are grouped in dense clusters at the tip of the stems.The tight buds are light green to straw-coloured, opening into light and dark purple flowers, which turn into fluffy white seedheads. Flowering profusely throughout the summer and autumn, there are always buds, flowers and seedheads on the plant at the same time.
Distribution and habitat
Linzia glabra occurs naturally in South Africa, where it is found in KwaZulu-Natal and Mpumalanga, as well as in Swaziland,Namibia, Tanzania and also Kenya, usually as a pioneer in disturbed ground.
Derivation of name and historical aspects
At the time of writing this plant of the week in 2003, this plant was called Vernonia glabra. The genus Vernonia is named after William Vernon (d. 1711), an English botanist who collected in Maryland in the late 1600's. The species name glabra is Latin and means smooth, referring to the smooth leaves.
Growing Linzia glabra
TheLinzia glabra at Kirstenbosch was collected in northern KwaZulu-Natal near Kosi Bay. The original plants were found growing in recently burned grassland and were resprouting strongly, with no flowers but new growth perfect for cuttings.
The inspiration for collecting this plant was another species, previously known asVernonia natalensis ( now Hillardiella aristata) that has been growing at Kirstenbosch for many years. It is a very striking plant with attractive silver-grey foliage in summer and masses of purple flowers at Christmas.
Linzia glabra has much more vigour than Hilliardiella aristata, but it took some time to show its value in the garden. By itself, the plant does not make much of an impact as the individual flowerheads are small and the tall green stems can look untidy standing alone, but mixed into an herbaceous border it has proved to be one of the best plants for summer display. Planted with different Agapanthus species, Geranium multisectum, Aerva leucura, Lobelia valida, Orphium frutescens, Orthosiphon labiatus and Diascia personata, Linzia glabra adds texture, height and splashes of colour from summer to autumn.
Linzia glabra does best planted in full sun and well-composted soil with good drainage. It grows actively during summer and should be cut down in the middle of winter when it gets untidy and goes slightly dormant. The new growth shoots out in early summer and the plants get stronger year after year as the clumps get more established.
New plants are easy to propagate from cuttings made from the new growth throughout the summer. Cuttings usually root within a month and are ready for planting within 3 months. It is best to plant the young plant out early in summer to give them a long growing season to establish themselves before going dormant in winter. Established plants can also be divided. Linzia glabra can also be propagated by seed sown in spring or early summer.
Other plants previously regarded as Vernonia species in Kirstenbosch are Hillardiella aristata, (previously Vernonia natalensis) with its silver-grey foliage and purple flowers, that makes a beautiful display in the rockeries at Christmas time, and the striking, tall shrub Gymnanthemum myrianthum ( previously Vernonia myriantha) that flowers in late autumn with big heads of mauve flowers.
Liesl van der Walt
Kirstenbosch National Botanical Garden
Plant Type: Perennial, Shrub
SA Distribution: KwaZulu-Natal, Mpumalanga
Soil type: Loam
Flowering season: Late Summer, Autumn
Flower colour: Purple, Mauve/Lilac
Aspect: Full Sun
Gardening skill: Average