
Flowering during the warm summer and into autumn, this tall, elegant
annual adds a cool and lush feeling to the garden. In nature they
are commonly found in the summer rainfall areas of South Africa,
especially the grasslands. Opportunistic annuals, they germinate
best in disturbed areas like roadsides where they manage to grow,
flower and seed before the onset of the dry, frosty winter.
The
wild foxglove varies in height, depending on the amount of water
it receives during the summer. In the garden with regular watering
they grow 1,5 - 2 metres tall. Some plants become quite bushy while
others remain single stemmed. The soft, green leaves are about 50mm
long and divided into 3 lobes with a bluntly serrated margin. The
leaves are carried on long thin stalks up the stems. Plants with
pink flowers usually have dark red stems while white flowering plants
have yellow-green stems.
The beautiful white or mauve foxglove-like flowers are carried
in pairs up the stems in tall, sparsely flowered spikes. Unfortunately
the promise of an overwhelming display is never fulfilled as only
two or three flowers on a stem open at a time. The bottom flowers
open first and form fruits while new buds are still developing at
the tip of the stem. Each flower is about 50 mm long with 5 lobes,
the bottom lobe longer than the others and streaked with delicate
lines running into the throat.
When in flower they create quite a buzz as a favourite of the
carpenter and honey-bees. In nature the wild foxglove flowers throughout
summer but at Kirstenbosch the best display is during the late summer
months (Feb-March). The small black seeds are formed in the 30 mm
long fruits which have two very prominent horns at their tips. Within
a few weeks of flowering the green fruits turn brown and dry, splitting
open to release the flat, pear shaped seeds. The leaves, stems and
flowers are covered in fine white hairs. The plants are slightly
sticky and when crushed give off a strong unpleasant smell. The
flowers last for a few days in the vase.
Growing Ceratotheca triloba
In the garden these annuals prefer rich, well-drained soils in
full sun or semi-shade. The wild foxglove can survive with very
little water, but to grow tall and lush, they need plenty of water
throughout the summer. For the best display, plant them close together
in large groups. They will seed themselves freely if left to go
to seed.
Propagate the wild foxglove by seed sown during spring or early
summer (Sept - Nov). Sow the seed evenly and not too thickly, in
seed trays filled with a well-drained medium. Cover the seeds with
a thin layer of white sand or fine milled bark, water well and place
the tray in light shade. Germination is usually very good, but the
young seedlings are often a bit slow to grow initially. They respond
very well to feeding with organic fertiliser like Seagro or Humac
as an initial boost. The seedlings can be planted into the garden
as soon as they are big enough to handle, usually about 6-8 weeks
after sowing.
This is the only species of Ceratotheca that is found in
South Africa. Ceratotheca means having horned capsules, from
the Greek kerato-, horned and theke, a case. The species
name triloba means three-lobed (Latin), alluding to the leaves.
Cerathotheca triloba is used in traditional medicine to treat
painful menstruation, stomach cramps, nausea, fever and diarrhoea.
Liesl van der Walt
Kirstenbosch
February 2001
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