Leaf hoppers and many other insects feed off plant sap

Sap is a fluid transported in xylem cells (tracheids or vessel elements) or phloem sieve tube elements of a plant. Fluid found in the vacuole of other cells is sometimes referred to as "cell sap". Other liquid compounds found in plants or exuded by plants, such as latex, resins, and mucilage are sometimes incorrectly referred to as sap. Image File history File links Size of this preview: 800 × 534 pixel Image in higher resolution (1600 × 1067 pixel, file size: 389 KB, MIME type: image/jpeg) Leaf Hopper nymph of the Common Jassid (Eurymela fenestrata). ... Image File history File links Size of this preview: 800 × 534 pixel Image in higher resolution (1600 × 1067 pixel, file size: 389 KB, MIME type: image/jpeg) Leaf Hopper nymph of the Common Jassid (Eurymela fenestrata). ... This box:      A fluid is defined as a substance that continually deforms (flows) under an applied shear stress regardless of how small the applied stress. ... Multiple cross sections of a stem showing xylem and companion cells[1] In vascular plants, xylem is one of the two types of transport tissue, phloem being the other. ... In vascular plants, phloem is the living tissue that carries organic nutrients, particularly sucrose, a sugar, to all parts of the plant where needed. ... The names Sieve tube element and Sieve tube member are synonyms and are used to describe a certain type of elongated cell in phloem tissue. ... For other uses, see Plant (disambiguation). ... This article is about the typesetting system. ... This article does not cite any references or sources. ... Mucilage is a thick gluey substance, often produced by plants. ...

Xylem sap consists primarily of water, with hormones, mineral elements, and other nutrients dissolved in the sap. Transport of sap in xylem is generally "basipetal", or upward from the roots toward the leaves. Over the past century, there has been some controversy regarding the mechanism of xylem sap transport, although most plant scientists today agree that the bulk of the evidence supports the cohesion-tension theory of xylem sap transport. Phloem sap consists primarily of water, with sugars, hormones, and mineral elements dissolved in the sap. Phloem sap transport occurs from sources (a location where carbohydrates are produced or stored) toward sinks (a location where carbohydrates are utilized). The pressure flow hypothesis proposes a mechanism for phloem sap transport. The cohesion-tension theory is a theory of intermolecular attraction commonly observed in the process of water travelling upwards (against the force of gravity) through the xylem of plants. ... The pressure flow hypothesis was a hypothesis proposed by Ernst Munch in 1930 that explained the mechanism of phloem translocation. ...

Maple syrup is made from reduced maple tree xylem sap. In some countries (e.g., Russia or Latvia) it is common to collect the early spring sap of birch trees (so called "birch juice") for human consumption; the sap can be used fresh or fermented. "Birch juice" is slightly sweet and very refreshing, but tends to become bitter in late spring; the rule of thumb is to collect it before any green leaves have appeared. Bottled maple syrup produced in Quebec. ... For other uses, see Maple (disambiguation). ... The coniferous Coast Redwood, the tallest tree species on earth. ... Multiple cross sections of a stem showing xylem and companion cells[1] In vascular plants, xylem is one of the two types of transport tissue, phloem being the other. ... Species Many species; see text and classification Birch is the name of any tree of the genus Betula, in the family Betulaceae, closely related to the beech/oak family, Fagaceae. ...

See also

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Sap

• Latex
• Resin

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References

• Angeles, G., B.J. Bond, J.S. Boyer, T.J. Brodribb, J.R. Brooks, M.J. Burns, J.M. Cavender-Bares, M.J. Clearwater, H. Cochard, J.P. Comstock, S.D. Davis, J.-C. Domec, L.A. Donovan, F.W. Ewers, B.L. Gartner, U.G. Hacke, T.M. Hinckley, N.M. Holbrook, H.G. Jones, K.L. Kavanagh, B.E. Law, J. Lopez-Portillo, C. Lovisolo, T.A. Martin, J. Martinez-Vilalta, S. Mayr, F.C. Meinzer, P.J. Melcher, M. Mencuccini, S.S. Mulkey, A. Nardini, H. Neufeld, J.B. Passioura, W.T. Pockman, R.B. Pratt, S. Rambal, H. Richter, L. Sack, S. Salleo, A. Schubert, P.J. Schulte, J.P. Sparks, J.S. Sperry, R.O. Teskey, and M.T. Tyree. 2004. The cohesion-tension theory. New Phytologist 163:451-452.
• Raven, P.H., Evert, R.F. and Eichhorn, S.E. 1999. Biology of Plants. W.H. Freeman.
• Taiz, L. and Zeiger, E. 1998. Plant Physiology. Sinauer Associates, Sunderland, Mass.