nectar(redirected from Extrafloral nectaries)
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, in Greek mythology, food and drink with which the Olympian gods preserved their immortality. Extraordinarily fragrant, ambrosia was probably conceived of as a purified and idealized form of honey. It was accompanied by nectar, wine of the gods.
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the sugary juice secreted by the nectaries of plants. Nectar is an aqueous solution of sugars (sucroses, glucoses, and fructoses), which contains small quantities of alcohols (for example, mannitol), mineral salts, acids, and enzymes, as well as dextrinlike, nitrogenous, and aromatic substances. It often contains the complex sugar melezitose. The sugar content varies in different plants: for example, the nectar of the horse chestnut contains only sucrose, and the nectar of rape only glucose and fructose. The nectar of many plants contains primarily sucrose and fructose. The sucrose content of nectar is 22–37 percent in black currants, 32–40 percent in red currants, 35–42 percent in gooseberries, 35–64 percent in raspberries, 46–49 percent in cherries, and 46–53 percent in apples.
For normal nectar secretion, all parts of the plant must be completely functional and contain a sufficient quantity of water. Otherwise the flow of nutrient matter to the flower is decreased and nectar production diminishes or, sometimes, ceases. The amount of nectar secreted by individual flowers varies for different species: for example, a lime blossom yields 0.15–7.46 mg of nectar, and a raspberry flower an average of 14 mg. Usually, the more flowers a plant has, the higher the plant’s nectar production per unit area (sweet clover has more than 1,700 billion flowers per hectare).
Nectar serves as food for honeybees and other insects (bumblebees, wasps, butterflies). It constitutes the most important part of the honey flow of honeybees, which gather nectar from nectaries with their proboscises and transport it to the hives in their crops. The nectar distributed in the cells of the honeycomb undergoes considerable changes, which begin in the crop of the bee. As a result of processing by hive bees, the nectar loses water. The enzymes in the bees’ saliva and in the nectar itself break down the sucrose into glucose and fructose, and the nectar is converted to honey.
Some plants (daphne, rhododendron, Korean rhododendron, azalea, false hellebore) secrete a poisonous nectar. Poisonous plants (henbane, hemlock, oleander, foxglove) elaborate nectars that do not transmit their toxic properties to the honey if no alkaloids permeate and no poisonous pollen falls into the nectars.