Sap is the lifeblood of your landscape and garden plants.
Sap is carried up the trunk or stem of a plant in the xylem and down through the phloem. Sap has different components, depending upon where it is found. Xylem sap carries water, hormones, and minerals from the roots to the leaves. Phloem sap conducts sugars, hormones, and minerals from leaves, where carbohydrates are produced through photosynthesis, to where they will be used or stored. Within the tiny cavities (vacuoles) of each plant cell, cell sap can be found. Cell sap contains sugars, waste, and minerals.
Who and what eats sap?
Well, we do, for one. Sap from sugar maple trees is boiled down to make maple syrup for our pancakes. Most living things, however, have a hard time eating sap. This is because of its high sugar content and the lack of certain gut microorganisms that aid digestion. That being said, members of the Hemiptera order, or true bugs, have no such problem.
Aphids, leafhoppers, sap beetles, spider mites, scale, and mealybugs all enjoy feeding on the sweet, nutrient rich sap of your garden plants. In addition to these pests, there are many living things that feed on sap indirectly, by eating the honeydew excreted by the sap eaters, including ants and whiteflies. [You may be surprised to learn that honeybees also collect honeydew and use it to make a unique, darker honey that is prized in Europe.] Sap from the aloe vera plant is widely used to help heal burns and other skin conditions.
What sap is not
Plants produce other liquids besides sap. These include latex, resin, and gums. When you pluck a ripe fig from your tree, or tug a dandelion from the lawn, the white milky ooze you see is not sap. It is latex and many people have skin sensitivities to it. Ten percent of all flowering plants (angiosperms) produce latex in response to injury or invasion. Latex is made up of sugars, oils, starches, alkaloids, resins, proteins, and gums. Gums are made from decomposed cellulose, while resins are made from essential oils. Fossilized resin is the gemstone amber. [Our word for electricity comes from the Greek word for amber because the stones create static electricity when rubbed.]
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