Greetings to all our Village plant enthusiasts. Welcome to the latest “Plant of Interest” article for 2016!! This week we’ll be looking at a member of the Legumaceae (Pea) family, formerly known as the Fabaceae family (on account of the nitrogen fixing properties of the roots of most plants in this family).
Calpurnia sericea (Mountain Calpurnia in English, Berg-geelkeur and tloele in Sesotho) is a perennial shrub of up to 2500mm, with many erect stems occurring from the Eastern Cape through to KZN. It occurs near streams on moist soils in grassveld areas, in close proximity to rocks and boulders. This species has been observed at a maximum altitude of 2000m A.S.L., and is endemic to South Africa.
Nitrogen fixation – a trait characteristic of the family – is a symbiotic process between the root systems of the plant and nitrogen fixing microorganisms, wherein atmospheric nitrogen is converted to a form of ammonia or nitrate that the host plant can assimilate. This increases the nutrient content of the soil surrounding the plant, thus preparing the soil for larger and more complex vegetation to grow in a given area over time. This modification is part of the process known as succession; whereby more complex and suitable vegetation takes over from earlier & simpler pioneer vegetation. Through this process, it is believed that complete plant communities may change over time, allowing even eventually for the transition between say, grassveld – and eventually into forest vegetation (although other factors, such as climate may also come into play). In the Eastern Free State this is most evident in montane Kloof areas.
The leaves of C. sericea are imparipinnately compound consisting of 3-13 pairs plus a terminal leaflet and measure 60-120mm long whilst the leaflets measure 5-20mm long X 5-12mm wide. Small pods, characteristic of the genus are produced, measuring 10-50mm X 3-10mm. The flowers are small and yellow in terminal clusters, each cluster measuring approx. 60-130mm long. Flowering usually takes place from Dec to Jan; although with the recent late rainfalls, flowers have been observed until late March.
The leaves of the Pea Family have been found to contain natural insecticidal chemical compounds. South Africa has a relatively small contingent within the family comprising 7 species, whilst the Free State is home to only 3 species.
Reportedly, C. sericea has been used to disinfect wounds in injured livestock and to kill lice. In humans the leaves may be used to alleviate itching & the symptoms of allergic rashes. In Nigeria the seeds have reportedly been used to treat abscesses. It also makes good firewood and the heartwood has been used in the construction of traditional rock & mud shacks.
Regarded as of Least Concern by SANBI on account of its stable presence throughout its distribution.
Head ranger: Clarens Village Nature Reserve