Developmental and Structural Section
Schuster, Tanja M. , Kron, Kathleen A. .
Ericoid Leaf Anatomy of 15 South African Erica L. Species.
THE highly specialized ‘ericoid’ leaf is characteristic of Erica L. and considered an adaptation for water use efficiency in the arid fynbos. Recurved leaf margins form the needle shape with a more or less narrow abaxial sulcus, which almost extends to the leaf apex and base. Ericoid leaf characteristics may yield information of systematic value in Erica. Leaf anatomy of 15 South African Erica species is evaluated and compared to three other taxa (Bejaria Mutis ex L., Calluna Salisb. and Rhododendron L.) of the Ericoideae clade using SEM. Taxa sampled represent differing habitats of the Cape Floristic Region, such as swamps, rock crevices, cliffs, dry sands and limestone. In the investigated Erica species, dome-shaped epidermal cells of the adaxial leaf surface, implicated in photon capture efficiency, are common. Leaf cross sections commonly show one layer of palisade cells, and a comparatively thicker layer of spongy parenchyma. Spherical deposits, possibly secondary metabolites, occur in these tissues in several taxa. Sclerenchymatous tissue, common to xerophytes, is also present. No stomata are present on the adaxial leaf surface. Stomata with a mostly smooth appearance are located alongside the midrib of the abaxial leaf surface and oriented with the short axis parallel to the midrib. Orientation and placement of guard cells are relatively uniform in the investigated Erica. The stomatal apparatus is raised above the epidermis (stalked in one case) and surrounded by dense trichomes in most species surveyed. Trichomes are variable in Erica with as many as five different hair types per leaf. Different trichomes may occur along the functional leaf margin, on the edge of the sulcus, the abaxial leaf surface and its midrib, at the base of the leaf and the petiole and the adaxial leaf surface. Dendritic, glandular, unicellular and uniserate multicellular trichomes occur and often show prominent waxy sculpturing.
Log in to add this item to your schedule
Ericaceae Phylogeny and Systematics
1 - Wake Forest University, Department of Biology, PO Box 7325, 226 Winston Hall, Winston-Salem, North Carolina, 27109-7325, USA
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM