Floral nectaries

It Is generally conceded that floral nectaries evolved as an attractant to pollinating Insects. The function of extrafloral nectaries Is not so obvious. Some suggest that the secretion of sugars Is associated with a shift from a "sink" to a "source of carbohydrates during development (, . Others propose that... 

Bentley, B. L. (1977). Extra-floral nectaries and protection by pugnacious bodyguards. Annual Review of Ecology and Systematics 8 407 127. 

Extra-floral nectaries) glandular structures outside the flower,... 

The study of sugar from floral nectary is important for identification if a rise or decrease in quantity or nectar quality. The plant may secret a little bit of nectar, but with high sugar concentration, or unlike, secret more quantities, but with low sugar concentration. These differences in nectar may vary depend on pollinator visitation. However, the frequency of honeybees that visit flowers may contribute for rising nectar production like change the sugar proportion. 

In Nitraria and Peganum, floral nectaries are present between the androecium and the gynoecium (this study Nair and Nathawat, 1958). They have been described as a more or less developed intrastaminal lobed disc in Peganum (Baillon, 1873 ... 

An intrastaminal floral nectary is common in Sapindales and most other rosids (Ronse De Craene and Haston, 2006). However, the presence of conspicuous nectariferous depressions in the petal radii, as in Peganum and Nitraria, is unusual. 

Extrafloral nectaries include a wide range of nectar-excreting structures, which are distinguished from their floral counterparts by the fact that they are not involved in pollination. Extrafloral nectar is typically dominated by sucrose and its hexose components glucose and fructose. The fact that these common sugars are acceptable to the majority of insects, combined with the exposed nature of extrafloral nectaries, makes them suitable food sources for abroad range of insects. Compared with floral nectar, extrafloral nectar often has increased fructose and glucose levels (Tanowitz... 

Baker, H.G. Baker, I. (1983). A brief historical review of the chemistry of floral nectar. In Bentley, B. Elias, T.S. (Eds.) The biology of nectaries. Columbia University Press, ISBN 978-0-231-04446-2, New York, USA... 

Marazzi, B., Endress, P. K., Paganucci de Queiroz, L. and Conti, E. (2006). Phylogenetic relationships within Senna (Leguminosae, Cassiinae) based on three chloroplastDNA regions Patterns in the evolution of floral symmetry and extrafloral nectaries. American Journal of Botany, 93,288-303. 

C. J. (2004). Floral anatomy of BromeUaceae, with particular reference to the evolution of epigyny and septal nectaries in commeUnid monocots. Plant Systematics and Evolution, 247, 215-231. 

Fig 8.6 Nitraria retusa. Floral bud, transverse section series. (A) Distal zone, five petals [p] with valvate aestivation and tips bent inwards surrounding postgenitally united carpel tips [c]. (B) Fifteen stamens surrounding the style. (C) Ovary at the level of the placentae. (D) Ovary, with two fertile locules, each with one ovule [o], and one sterile, empty locule [si]. (E) Floral hase, with five antesepalous depressions (nectaries). Scale bars (A)-(E) = 1 mm. 

The ratio of sucrose-derived hexoses, fructose and glucose, in the floral nectar of Anigozanthos flavidus (Haemodoraceae) was observed to be different from 1 1, which cannot be explained by the simple action of inver-tases. Various NMR techniques were used to investigate how such an unbalanced ratio of the two nectar hexoses can be formed. In vivo MRI (e.g. cyclic J cross-polarization) was used to detect carbohydrates in vascular bundles and H-1 spin echo imaging non-invasively displayed the architecture of tepal nectaries and showed how they are connected to the vascular... 

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