Vasculature and ultrastructure of the floral and stipular nectaries of Vicia faba (Leguminosae)

Abstract

The floral nectary of Vicia faba L. (faba bean, broad bean, or field bean) consists of a disk which bears a long, basal, tapered projection. Large, open stomata, located at the tip of the projection, probably serve as exits for nectar. Phloem is present in the floral nectary. The extrafloral nectary consists of numerous secretory and nonsecretory trichomes aggregated on the abaxial surface of each stipule. Both xylem and phloem are present in the stipule beneath the extrafloral nectary. In both nectary types, large companion cells accompany the phloem. Epidermal and parenchyma cells of the floral gland, as well as the companion cells, develop wall ingrowths and are therefore transfer cells. Ultrastructural evidence suggests a granulocrine mechanism of nectar secretion in the floral nectary, wherein both apoplastic and symplastic routes for prenectar movement and escape appear feasible. Floral and extrafloral nectar differ in sugar concentration and in the predominance of sucrose, both of which are higher in exudate from floral nectaries.

Ontogenia dos nectários extraflorais de Triumfetta semitriloba (tiliaceae)

“…O acúmulo de néctar entre a cutícula e as paredes das células da epiderme secretora, bem como sua posterior liberação por rompimento da cutícula, é amplamente relatado na literatura (Durkee, 1982(Durkee, , 1983Mohan & Inamdar, 1986;Davis et al, 1988;Subramanian & Inamdar, 1989). Quando não ocorre rompimento de cutícula, podem existir poros (Findlay & Mercer, 1971;Fahn, 1979;Sawidis et al, 1989;Machado, 1999) ou regiões de maior permeabilidade na cutícula (Roshchina & Roshchina, 1993).…”

Nectar and flower production in Vicia faba L. (field bean) at ambient and elevated carbon dioxide

“…Vicia faba nectaries are described by Davis et al (1988) and illustrated in Davis and Gunning (1992 (Gates et al, 1983; though see Stoddard, 1993) (Kato, 1988 (Harder and Barrett, 1996;Snow et al, 1996) and increased levels of self-pollination, particularly geitonogamy (Handel, 1983;Barrett, 1995, 1996). Pollen flow per flower can sometimes, therefore, be reduced by increasing floral display (Harder and Barrett, 1995).…”

The effect of resource provisioning and sugar composition of foods on longevity of three Gonatocerus spp., egg parasitoids of Homalodisca vitripennis

“…Floral and extraXoral nectar typically consist of phloem, or phloem and xylem secreted by specialized stomata (Davis et al, 1988;GaVal et al, 1998;Razem and Davis, 1999;Fahn and Shimony, 2001;Wist and Davis, 2006). Xylem is generally greater than 98% water with some amino acids (Anderson et al, 1989), therefore simple soluble sugars present in Xowers would mostly consist of phloem present in vascular tissues and nectar.…”