 |  Corema conradii twigs (left, bar=5 mm) and leaves (above, bar=2mm) . The groove is on the underside. Click on images for larger versions. |
These are small linear* leaves in which "the edges of the leaf are rolled inwards on the undersurface and almost meet along the median line, leaving only a very narrow longitudinal slit; the outer surface is hard and waxy and does not allow for any transpiration. This leaf-form is characteristic of most species of Erica and Calluna and hence is referred to as "ericoid". Heathland families other than the Ericaceae may possess erocoid leaves, e.g., some heathland members of the Dilleniaceae, Fabacese and Myrtaceae. Some species may even possess leaves grooved above, not below."1
*Linear: with margins straight, parallel, length to width ratio between 12:1 and 6:1.2 | Corema conradii twigs (left, bar=5 mm) and leaves (above, bar=2mm) . The groove is on the underside. Click on images for larger versions. |
1.Text from p. 6 in: Specht, R.L. 1979. Heathlands and related shrublands of the world. In: Specht, R.L. ed.
Heathlands and related shrublands 1. Descriptive studies (Ecosystems of the world Vol. 9A, D.W. Goodal, Editor in Chief), pp. 1-18.
Amsterdam: Elsevier.
2. Simpson, M.G. 2006. Plant systematics. Elsevier.