Threatened
Plants Programmes: Lowveld NBG
Cycads, Dioscorea, and Acacia
In
2001, the Lowveld National Botanical Garden (LNBG) in Nelspruit, like most
of the 22 participating botanical gardens in southern Africa, submitted
its proposal for a Threatened Plants Programme (TPP) to the SABONET Steering
committee. Funds amounting to 3,000.00 US dollars were awarded for each
project. The Lowveld NBG began its project in 2002 with much enthusiasm.
Cycads
Traditionally,
cycads (Encephalortos sp.) have been incorporated in LNBG’s TPP since
1985, as the garden boasts an almost complete living collection of all African
cycads and several gene banks. Cycads were selected specifically because
of their status as threatened species and their outstanding horticultural
value. This project is nearing completion.
Dioscorea
A
wild yam (Dioscorea sp. nov) was selected for the TPP, for two main
reasons:
These plants have medicinal value, and are currently under
pressure due to their small world population.
The plants have unsurpassed horticultural potential, owing
to their pachycaul growth form (P.J.H. Hurter, 2002, 2003).
Acacia
An
Acacia sp. nov. was selected for the TPP for the following reasons:
Its small world population and localised distribution.
The need to
Objectives
The
objectives of the LNBG TPP are to:
Cultivate these narrow endemics and eventually make them available
for public use.
Investigate contributory factors to the rarity and localised
distribution of the two endemics.
Continuously investigate major threats to these plants in
situ and verify their status.
Ex situ Propagation
Two
separate (one in the LNBG, and in one other
SANBI
garden)
living gene banks of Dioscorea sp. nov. have been established.
Combined, these two living collections consist of approximately 1,250 seed-grown
individuals. Germination of this taxon appears to be excellent with germination
rates of as much as 80–95 percent.
A
community-run nursery and on-site ex situ conservation programme
have been established in this taxon’s area of occurrence, in order to cultivate
plants from seeds. This aims to relieve pressure put on the wild population
by the local inhabitants. More than 2,000 seeds have also been collected
and sent to the Kew Millennium Seed Bank Project for cryo-preservation.
The
propagation of Acacia sp. nov. has proved very disappointing,
with only five seed-grown individuals currently surviving out of several
seeds sown. There is a need for further research as the taxon appears to
be a hyper-accumulator. This is a fact that does not bode well for further
ex situ conservation efforts at this stage.
Future Plans
Recollect
seeds of Acacia sp. nov. and try various cultivation techniques.
Test
taxon for hyper-accumulation.
Continued
supply of seeds for cryo-storage (for the Kew Millennium Seed Bank Project)
will be maintained for both taxa, when necessary.
—Tovowani Mukoma
SABONET News 9.1: 45
HURTER,
P.J.H. 2002. Threatened plant programmes.
SABONET News 7(3): 222-223.
HURTER,
P.J.H. 2003. A new pachycaul Dioscorea
species from Mpumalanga Province, South Africa and its conservation. Aloe
40(2&3): 73-75.
MAUNDER,
M. 2002. IUCN Policy on the management
of ex situ populations for conservation. SABONET News 8(1):
18-19
