Tetradenia - having four glands
riparia - growing on banks of rivers
encounter with this plant in flower in the wintry, dry bush is most
surprising. There is the impression of soft lilac mist on bare grey
branches, quite incongruous with the dryness of the surrounding
It is cultivated for this spectacular show which occurs when there
is not much else in flower. The flowers range from white to lilac
including some with pink flowers.
The type of display which you will get depends on whether you have
a male or female plant! Male and female flowers are borne on separate
plants in spikes which differ in size and shape. The male flower
spikes in profusion create more of the "mist" effect than
the female flowers which tend to be more compact. The flowers usually
appear when the plants are bare and are carried in the top section
of the branches. Flowering occurs from June until August which coincides
with the frosts in Highveld gardens. The flowers may be spoiled
by this so it is a good idea to plant the ginger bush in a warm
spot such as against a north-facing wall or on a succulent rockery.
The ginger bush is a tall, aromatic shrub up to 3 m in height,
occasionally reaching 5 m. It is slightly succulent and has an irregular
branch pattern. The stems are brown and smooth, except for the younger
portions which are covered with glandular hairs and have a ruby
tinge. The glandular hairs also cover both surfaces of the leaves
and make them slightly sticky to the touch.
The leaves are a bright green and are slightly heart shaped with
the margin irregularly and bluntly toothed. Like many Lamiaceae
species (which includes familiar culinary herbs such as thyme, sage
and rosemary) the younger branches are distinctly four-angled in
cross section. The ginger bush is no relation of the true ginger
plant of which the underground stem is commonly used for flavouring
and in preserves.
The natural habitat of Tetradenia riparia is along river
banks, forest margins, dry wooded valleys and hillsides in areas
where there is little frost. The natural distribution ranges from
KwaZulu-Natal, Northern Province, Mpumalanga in South Africa to
Swaziland, Namibia, Angola and northwards through tropical east
Africa into Ethiopia.
This plant was previously classified under the genus Iboza,
which was derived from its Zulu name and apparently this refers
to the aromatic qualities of the plant. The Zulu people have many
uses for the plant including the relief of chest complaints, stomach
ache and malaria. Inhaling the scent of the crushed leaves apparently
also relieves headaches.
Growing Tetradenia riparia
This is a rewarding garden plant which is fast growing
- up to 80cm per year and which will flower in its first year. It
grows easily in light, well drained and well composted soil. It
prefers water in summer but not as much in winter, thus making it
is a good water wise plant for summer rainfall areas, especially
the bushveld regions. It should be pruned back hard after flowering
to keep it neat and promote flowering. Plant in full sun, except
in very hot areas where midday shade or light shade will be beneficial.
The ginger bush is best propagated from cuttings,
even quite large truncheons can be successful. They should be rooted
in river sand and monitored for any signs of rotting, as they are
slightly succulent. Seed may be difficult to obtain if your garden
has only male or female plants in it.
The flowering stems do well in water for flower arranging.
The ginger bush is associated with a moth (Trichoplusia molybdina)
of the predominately night-flying Noctuid family, but the flowers
also attract other insects which are necessary to bring insect-feeding
birds into your garden.
Witwatersrand National Botanical Garden