Vernonia 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
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 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.
Vernonia 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
Derivation of the name
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.
There are more than a thousand species of Vernonia found
in the warmer countries in the world, with about 40 species widespread
throughout southern Africa, except in the south-western Cape.
Growing Vernonia glabra
Vernonia 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 vernonia was another species,
Vernonia natalensis that has been growing at Kirstenbosch
for many years. Vernonia natalensis is very striking with
attractive silver-grey foliage in summer and masses of purple flowers
Vernonia glabra has much more vigour than Vernonia natalensis,
but it took some time to show its value in the garden. By itself,
the plants do not make much of an impact as the individual flower
heads 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,
Lobelia valida, Orphium
labiatus and Diascia personata, Vernonia glabra adds
texture, height and splashes of colour from summer to autumn.
Vernonia 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. Vernonia glabra can also be propagated
by seed sown in spring or early summer.
Vernonia species in Kirstenbosch are 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 V. myriantha that flowers in late autumn with big heads
of mauve flowers.
Liesl van der Walt
Kirstenbosch National Botanical Garden