Hemizygia stalmansii (Labiatae), a New Species from Mpumalanga, South Africa and Swaziland

Abstract

Songimvelo Game Reserve (Map 1) spans an area of about 49,000 ha and is divided into two sections by two privately owned farms (Stalmans et al. 1999). The southwestern part of the reserve includes 10,000 ha of wide, flat to gently sloping valley floor surrounding the Komati River and it is here that most of the development of tourism infrastructure and game occurs. The northeastern section includes the steep, narrow valley of the Lomati River. This area is rich in plant species, including a number of narrow endemics. The rocks that occur in the Reserve are very diverse and include serpentinites and komatiites; those in the Barberton Greenstone Belt are among the oldest rocks in the world. They are soft and weather quickly to give nutrient-rich soils and usually occur at the lower altitudes. Hard quartzites produce round-topped ridges. Thus the soils at Songimvelo Game Reserve are physically and chemically highly variable. The serpentine (ultramafic) soils bear characteristic vegetation due to the high concentrations of nickel, chromium and magnesium; there are 30 taxa endemic to the serpentine of the Barberton Greenstone Belt (Balkwill & Balkwill 1999). Altitude within the Reserve ranges from 580 m a.s.l. at the Lomati and Komati River exits, to 1,900 m at the Maid of the Mist Mountain. The terrain is highly dissected giving very high habitat diversity. Rainfall ranges from 800 to 1,600 mm per annum. Rainfall tends to increase with altitude. The adjoining Malolotja Nature Reserve in Swaziland has similar geology and ecology to Songimvelo (Lyon 1996).