GONZALEZ Ana Maria
"Nectarios extraflorales en Turnera. Serie Canaligerae y Leiocarpae".
GONZALEZ, ANA MARIA
Ed. Instituto de Botánica del Nordeste.
Lugar: Corrientes; Año: 1996 vol. 9 p. 129 - 143
NECTARIOS EXTRAFLORALES EN TURNERA, SERIES CANALIGERAE Y LEIOCARPAE Por ANA MARÍA GONZÁLEZ° Summary This paper describes the anatomy of extrafloral nectaries of seventeen species of Turnera, belonging to Canaligerae and Leiocarpae series. Foliar nectaries are born on the petiole apex or at the base of leaf blades; they are discoid, cupular with a rim surrounding a cup. Although the size and morphology vary within species, the structure of the nectaries basically is the same, they are composed of a secretory epidermis, which consists of 1-4 layers of columnar cells. Underlying this tissue is the glandular parenchyma, usually 2-8 layers in thickness. The body of the nectary is formed by ground parenchyma, druses of calcium oxalate and tannin idioblasts are abundant in this area. The vascular supply derives from the median petiole bundle. It is provided by 1 or 2 lateral bundles which branch repeatedly in the ground parenchyma of the nectary. In all the studied nectaries the vascular tissue ended as isolated strands of phloem among the secretory parenchyma cells. For the first time, tracheoids are described in nectaries, this elements were known only in the veinlets of Angiosperms leaves. Most of the species of series Canaligerae, have a pore in the secretory epidermis, which is a protuberance determined by the glandular parenchyma; the surface is flat or crateriform. A thick cuticle covers the epidermis, only in the center of the pore it is thin enough to allow the nectar extrusion. In no species was observed cuticle rupturing. The Leiocarpae nectaries are characterized by a lesser development or absence of the pore.