Strelitzia reginae 'Mandela's Gold' is a rare yellow form
of the well-known crane flower, Strelitzia reginae.
Yellow-flowering strelitzias have been known for a number of years,
plants have cropped up in France, California, Australia, Japan and
in South Africa at a few locations in Eastern Cape and at Kirstenbosch
and the Karoo Desert National Botanical Gardens, but always as isolated
specimens. Left to their own devices, the seeds from these yellow
forms will not breed true as they will most likely have been pollinated
by an orange plant. To get yellow progeny, two yellow plants must
be crossed. At Kirstenbosch in the 1970's, there were seven yellow
plants in the nursery. John Winter, who was curator during this
period, began a project to increase the stock. It took nearly twenty
years of careful selection and hand-pollination, and in 1994 the
original stock had been built up enough to enable us to introduce
the yellow strelitzia to horticulture. It was released and traded
under the name 'Kirstenbosch Gold' until 1996 when the NBI was granted
permission to re-name it in honour of Nelson Mandela.
Gold' is a stemless, evergreen clump-forming perennial. Greyish
green, banana-like leaves grow to a height of about 1.5 m and during
winter and spring the large bird-like flowers are held above the
foliage on the tips of long, sturdy stalks. The structure and pollination
of the flowers is fascinating. The hard, beak-like sheath from which
the flower emerges, is called the spathe. This is held at right
angles to the stem, and has the appearance of a bird's head. Each
spathe contains 4 to 6 flowers, and these emerge one at a time from
the spathe. Each flower consists of 3 clear yellow sepals and 3
deep purple petals. The yellow sepals give the appearance of a crest
on the 'bird's' head. Two of the purple petals are joined together
around the stamens and the style to form an arrow-like structure.
The third purple petal is visible as a small scale.
Nectar is produced by a gland at the base of the flower. In fact,
so much nectar is produced that it leaks out and drips down the
side of the spathe. Although it is not certain exactly which bird
is the pollinator, when it comes to feed on the nectar, it perches
on the arrow-like purple petals, which open to expose the anthers
and the sticky pollen adheres to the feet of the bird. The bird
then transfers this pollen to the stigma of the next flower it visits.
pollinator does not live in Cape Town and we get absolutely no seed
unless we hand-pollinate. This appeared to be a curse at first but
is actually a blessing, as we can be 100% sure that our seed is
100% pure yellow. In areas where the pollinator lives, to ensure
100% purity, the yellow plants would have to be physically enclosed
or separated from any orange plants in the vicinity.
Hand pollination is done by mimicking the action of the bird,
i.e. using a stick or a finger to depress the purple petals to expose
the anthers, scraping some pollen off and transferring it to a receptive
(shiny and sticky) stigma on another plant. After fertilization,
the fruits develop inside the spathe. As they ripen, the capsules
swell and protrude from the spathe, change from green, to brown
and woody, and split to release the distinctive shiny black seeds
with their tuft of oily orange hairs (the aril).
At Kirstenbosch, the grey squirrel that Cecil John Rhodes brought
with him from England, Sciurus carolinensis, which has naturalized
itself here, will consume nearly all the crop if unchecked. It takes
the entire, almost-ripe green capsule, leaving nothing but the vandalized
remains of the spathe behind. We have battled for years to find
the best way of protecting our developing seed, and short of erecting
a cage around the plants in the garden, we have found that enclosing
each fertilized flower in fine-mesh chicken wire keeps the squirrels
Growing Strelitzia reginae 'Mandela's
Strelitzia reginae 'Mandela's Gold' is an easy plant to
grow and will thrive in most soils.
Ideal conditions are full sun, rich, well-drained loam soil with
a pH of approximately 7.5, regular deep watering in summer and liberal
applications of fertilizer in early summer. Bonemeal and plenty
of mature compost should be mixed into the soil when planting. Plants
will respond well to generous applications of manure and compost
or additional fertilizer watered in about once a month during summer.
A fertilizer with the proportions 3:1:5 encourages flowering, and
can be alternated with other formulations.
In South Africa and other sunny countries, strelitzias will also
do well in semi-shade, but in less sunny regions, they need as much
sun as they can get if they are to flower well. Once established,
they can survive with very little water, and they are tolerant of
wind and coastal conditions. But 'Mandela's Gold' is sensitive to
cold and needs a sheltered position against a north- or west-facing
wall in areas that experience frost, and is not suitable for permanent
outdoor cultivation in regions that experience a winter low of -7
to -1 ºC
/ 30 to 40 ºF
(zone 9) or lower.
'Mandela's Gold' is a striking feature plant, a decorative garden
subject and adds a tropical feel to courtyards and swimming pool
areas. It is also an excellent cutflower. It is suitable for cultivation
in large tubs and containers but for better flowering performance
it should then be fed with a dilute liquid fertilizer at least every
second week, particularly at the beginning of the growing season.
In cold climates it can be grown in a sunny or brightly-lit conservatory.
Propagation is by seed or division. The plants are slow-growing
and large clumps that are split or moved will take at least two
years to re-establish themselves and flower again. To get a mature
flowering plant from seed: under ideal conditions it takes about
3 years; but under less than ideal conditions it can take from 5
to 7 years. For best results sow fresh seed in spring or early summer.
To improve germination, the seed can be soaked in a solution of
ethrel, but this treatment is not necessary for germination to occur.
Without ethrel treatment approx. 50% of the seed should germinate
in 4 to 8 weeks with a further 30% germinating sporadically for
up to one year after sowing. With ethrel treatment, 80% of the seeds
should germinate within the first 4 to 8 weeks.
Before sowing, remove the bright orange aril and soak the seed
in a solution of ethrel at a concentration of 2000 ppm active constituent,
for 48 hours. Sow in seedtrays filled with a well-drained soil medium
at a depth of 1 to 1½ times the size of the seed. A constant
temperature of 25C is most suitable for germination as low temperatures
retard germination. Seedlings should be a good size before being
transplanted (two to three leaves) into a well-drained potting medium.
In our nursery we have found that the young plants are best grown
in semi-shade, as the leaves tend to burn in direct sunlight. Regular
repotting allows the young plant to develop rapidly. Restricting
the root development retards growth.
Seed of 'Mandela's Gold' is available for sale from the Seed Room
at Kirstenbosch, although stocks are limited and there is a waiting
list. For the current price or to place an order please contact
the Seed Room, Kirstenbosch NBG, Private Bag X7, Claremont 7735,
Telephone +27 (021) 799 8624 or Fax +27 (021) 762 8239.
WINTER, JOHN. 1984. Going for gold. Veld & Flora 80:
Kirstenbosch National Botanical Garden