Walking down the Camphor Avenue at Kirstenbosch, one can not but
stop to admire the clumps of Streptocarpus formosus flowering
on the ground. Formosus meaning beautiful, is a perfect description
of this species with its trumpets of soft mauve flowers. In nature
they grow around Port St Johns in the Transkei and the sandstone
gorges of Umtamvuna and Oribi, in Kwazulu-Natal. In these sub-tropical
forests the summers are humid and wet, while the winters are warm
and dry. Streptocarpus formusus is found along the gorges,
growing in pockets of well-drained soil between the rocks.
are fascinating for each leaf is an individual plant with its
own roots and flowering stems. Streptocarpus formosus plants
form thick clumps of long, strappy leaves arranged in a rosette.
The dark green leaves are almost succulent with many little, white
hairs. The veins of the leaves are very prominent, especially on
the underside where the midrib and side branches form thick ridges.
The tips of the leaves often die off as they get older and when
stressed by drought or low temperature. Although the brown ends
may look unattractive, this survival tactic does not harm the plants.
The leaf simply forms an abscission layer and continue with new
growth from the base.
formosus flowers almost throughout summer, from late spring
to autumn. One or two flowers are formed at the tips of the long
flowering stems. Each leaf usually has a few flowering stems of
different ages, growing from the base. The large trumpet-shaped
flowers are white with soft mauve markings that run along the edge
of the petals and into the distinctive, yellow-floored throat. Each
delicate flower lasts a few days even when cut for the vase. The
plants cross-pollinated easily with other species or in many instances
are self-pollinated. Thousands of fine brown seeds are released
within a month or two from long fruits. When dry, the fruits have
an interesting way of unfolding like a spiral and hence the name
Streptocarpus which means " twisted fruit" in Greek
(streptos = twisted and carpus= fruit).
Growing Streptocarpus formosus
In most collections plants come and go, with a few surviving the
good and the bad times. At Kirstenbosch Streptocarpus formosus
has proven to be one of the most reliable and beautiful, flowering
as pot plants in the glasshouse and planted out in the garden. In
a mild climate like Kirstenbosch, the plants survive the winters
outside as long as they do not get too wet. Watering streptocarpus
should be done with care. Give a thorough watering only when the
plants are dry. During the warm summers they are actively growing
and need plenty of water, but during the cool winters very little
water should be given. Streptocarpus should rather be under watered
than over watered. Even when slightly wilted from drought, they
will quickly recover with a good watering. Often plants look wilted
when over-watered, so feel the soil before watering. Plant streptocarpus
in a well-composted medium with good drainage. The soil mixture
sold at nurseries for African violets usually works well. The plants
are very sensitive to light, easily burned by sun and reluctant
to flower in deep shade. Light shade with good ventilation is best
for growing healthy plants with plenty of flowers. Streptocarpus
respond well to feeding during summer when they are actively growing.
Removing the dead leaves and flowers regularly keeps the plants
attractive and healthy.
Streptocarpus formosus can be propagated from
a single leaf. Simply break of a young, healthy leaf at its base
and place it in a well-drained medium like sand or compost. If many
new plants are required, the leaf can be cut along the midrib or
horizontally into segments. Wedge the cut edges into the rooting
medium. Water thoroughly and place the cuttings in the shade. Within
a month or two, new leaves will form along the edge placed in the
rooting medium. The old leaves turn brown and dead as the young
leaves start to grow. Once the new plants are well established,
they can be potted into small pots and grown on. To get new plants
identical to the parents, it is best to propagate from cuttings.
Streptocarpus formosus can also be propagated from seed sown
during the warm spring and summer months. Carefully scatter the
seeds on a moist, well-drained medium and place in a spot with good
light but not direct sunlight. Water regularly with a fine spray
not allowing the seedlings to dry out. Germination is usually within
a month. Plant the seedlings into small pots only once they are
quite big and strong. Transplant again into bigger pots when the
roots have filled the small pots. Mature plants often loose their
vigor after about 3-5 years and should be replaced by younger plants.
Streptocarpus and African violets belong to the same family, Gesneriaceae.
More than 100 species of Streptocarpus are found widespread
from central Africa to South Africa and Madagascar. Most of the
species are found in southern Africa, but it is in Europe and America
that streptocarpus is well known as a pot plant. In 1826 the collector
James Bowie took the first plants of Streptocarpus rexii to
Kew Botanical Gardens in England. As more species were introduced
into cultivation different hybrid streptocarpus were produced. Today
new hybrids are still introduced to the huge and growing pot plant
market, with growers like Dibleys' Nursery in Wales specializing
mainly in streptocarpus. Rex and Gareth Dibley have written a Wisley
handbook full of interesting facts and tips on growing streptocarpus
that can be consulted for more information.
Author: Liesl van der Walt