Mature leaves of Mentha longifolia, commonly known as wild spearmint or horse mint and balderjan in Afrikaans, show the characteristic sunken veins on their upper surfaces. The lanceolate, stalkless leaves curve down to their tapering tips as they lengthen to their full size. The dense cluster of acutely pointed emerging leaves ascending at the stem tip are pale to yellow green. Leaves of this plant may be toothed or untoothed and sometimes hairy. Leaves smell of mint when crushed.
The plant is a rhizomatous herb reaching 1,5 m in height. The species distribution covers much of South Africa, barring parts of the arid northwest and much of KwaZulu-Natal. The habitat is moist places and river banks.
Three variations of M. longifolia have been recognised in the literature, all associated with cold drinks, teas and various medicinal applications prepared from the leaves (Manning, 2009; Roberts, 1990).