LATEX

Latex is a stable dispersion (emulsion) of polymer microparticles in an aqueous medium. It is found in nature, but synthetic latexes can be made by polymerizinga monomer such as styrene that has been emulsified with surfactants.

Latex as found in nature is a milky fluid found in 10% of all flowering plants (angiosperms). It is a complex emulsion consisting of proteins, alkaloids, starches, sugars, oils, tannins, resins, and gums that coagulate on exposure to air. It is usually exuded after tissue injury. In most plants, latex is white, but some have yellow, orange, or scarlet latex. Since the 17th century, latex has been used as a term for the fluid substance in plants. It serves mainly as defense against herbivorous insects. Latex is not to be confused with plant sap; it is a separate substance, separately produced, and with separate functions.

IUPAC definition.

Latex: Colloidal, dispersion of polymer particles in a liquid.

Synthetic latex: Latex obtained as a product of an emulsion,
mini-emulsion, micro-emulsion, or dispersion polymerizati.

Extraction of latex from a tree, for use in rubber production

The word is also used to refer to natural latex rubber, particularly non-vulcanized rubber. Such is the case in products like latex gloves, latex condoms and latex clothing. Many people are allergic to rubber latex.

Biology
Articulated Laticifers

The cells (laticifers) in which latex is found make up the laticiferous system, which can form in two very different ways. In many plants, the laticiferous system is formed from rows of cells laid down in the meristem of the stem or root. The cell walls between these cells are dissolved so that continuous tubes, called latex vessels, are formed. Since these vessels are made of many cells, they are known as articulated laticifers. This method of formation is found in the poppy family and in the rubber trees (Para rubber tree, members of the family Euphorbiaceae, members of the mulberry and fig family, such as the Panama rubber tree Castilla elastica), and members of the family Asteraceae. For instance, Parthenium argentatum the guayule plant, is in the tribe Heliantheae; other latex-bearing Asteraceae with articulated laticifers include members of the Cichorieae, a clade whose members produce latex, some of them in commercially interesting amounts. This includes Taraxacum kok-saghyz, a species cultivated for latex production.

Non-Articulated Laticifers

In the milkweed and spurge families, on the other hand, the laticiferous system is formed quite differently. Early in the development of the seedling latex cells differentiate, and as the plant grows these latex cells grow into a branching system extending throughout the plant. In many euphorbs, the entire structure is made from a single cell – this type of system is known as a non-articulated laticifer, to distinguish it from the multi-cellular structures discussed above. In the mature plant, the entire laticiferous system is descended from a single cell or group of cells present in the embryo.

The laticiferous system is present in all parts of the mature plant, including roots, stems, leave, and sometimes the fruits. It is particularly noticeable in the cortical tissues. Latex is usually exuded as a white liquid, but is some cases it can be clear, yellow or red, as in Cannabaceae.

Productive Species

Latex is produced by 20,000 species from over 40 families occurring in multiple lineages in both dicotyledonous and monocotyledonous types of plant. It is also found in conifers and pteridophytes. Among tropical plant species 14% create latex, as opposed to 6% of temperate plant species. Several members of the fungal kingdom also produce latex upon injury, such as Lactarius deliciosus and other milk-caps. This suggests it is the product of convergent evolution and has been selected for on many separate occasions.

Defense Function

Latex functions to protect the plant from herbivores. The idea was first proposed in 1887 by Joseph F. James who noted that latex

... carries with it at the same time such disagreeable properties that it becomes a better protection to the plant from enemies than all the thorns, prickles, or hairs that could be provided. In this plant, so copious and so distasteful has the sap become that it serves a most important purpose in its economy.

 

Rubber latex

Evidence showing this defense function include the finding that slugs will eat leaves drained of their latex but not intact ones, that many insects sever the veins carrying latex before they feed, and that the latex of Asclepias humistrata (sandhill milkweed) kills by trapping 30% of newly hatched monarch butterfly caterpillars.

Other evidence is that latex contains 50–1000× higher concentrations of defense substances than other plant tissues. These toxins include ones that are also toxic to the plant and consist of a diverse range of chemicals that are either poisonous or "antinutritive". Latex is actively moved to the area of injury; in the case of Cryptostegia grandiflora, this can be more than 70 cm.

The clotting property of latex is functional in this defense since it limits wastage and its stickiness traps insects and their mouthparts.

It has been noted that while there exist other explanations for the existence of latex including storage and movement of plant nutrients, waste, and maintenance of water balance that "[e]ssentially none of these functions remain credible and none have any empirical support".

Applications

The latex of many species can be processed to produce many materials.

Natural rubber is the most important product obtained from latex; more than 12,000 plant species yield latex containing rubber, though in the vast majority of those species the rubber is not suitable for commercial use. This latex is used to make many other products as well, including mattresses, gloves, swim caps, condoms, catheters and balloons.

Opium poppy exuding fresh latex from a cut

Balatá and gutta percha latex contain an inelastic polymer related to rubber.

Latex from the chicle and jelutong trees is used in chewing gum.

Dried latex from the opium poppy is called opium, the source of many useful opiates and other alkaloids of high value.

Synthetic latexes are used in coatings (e.g. latex paint) and glues because they solidify by coalescence of the polymer particles as the water evaporates, and therefore can form films without releasing potentially toxic organic solvents in the environment. Other uses include cement additives, and to conceal information on scratchcards. Latex, usually styrene-based, is also used in immunoassays.

Latex – both synthetic and natural – is used to make mattresses as an alternative to memory foam as it had very similar properties and is preferred as a natural alternative.

Latex Clothing

Latex is used in many types of clothing. Worn on the body (or applied directly by painting) it tends to be skin-tight, producing a "second skin" effect.

Allergic Reactions

Some people have a serious latex allergy and exposure to latex products such as latex gloves can cause anaphylactic shock. Guayule latex has only 2% of the levels of protein found in Hevea latexes, and is being researched as a lower-allergen substitute.mAdditionally, chemical processes may be employed to reduce the amount of antigenic protein in Hevea latex, yielding alternative materials such as Vytex Natural Rubber Latex Which provide significantly reduced exposure to latex allergens.

About half of people with spina bifida are also allergic to natural latex rubber, as well as people who have had multiple surgeries, and people who have had prolonged exposure to natural latex.

Environmental Impacts
Microbial Degradation

Several species of the microbe genera Actinomycetes, Streptomyces, Nocardia, Micromonospora, and Actinoplanes are capable of consuming rubber latex.
References

Footnotes

1. ^ The polymer in the particles may be organic or inorganic.

Notes

1. ^ ^{a b c d e f g h} Anurag A. Agrawal &d Kotaro Konno (2009). "Latex: a model for understanding mechanisms, ecology, and evolution of plant defense Against herbivory". Annual Review of Ecology, Evolution, and Systematics 40: 311–331. doi:10.1146/annurev.ecolsys.110308.120307.
2. ^ Paul G. Mahlberg (1993). "Laticifers: an historical perspective". The Botanical Review 59(1): 1–23. doi:10.1007/bf02856611, JSTOR 4354199.
3. ^ ^a b c Stanislaw Slomkowski, José V. Alemán, Robert G. Gilbert, Michael Hess, Kazuyuki Horie, Richard G. Jones, Przemyslaw Kubisa, Ingrid Meisel, Werner Mormann, Stanisław Penczek & Robert F. T. Stepto (2011). "Terminology of polymers and polymerization processes in dispersed systems (IUPAC Recommendations 2011)" (PDF). Pure and Applied Chemistry 83 (12): 2229–2311. doi:10.1351/PAC-REC-10-06-03.
4. ^ "Taraxacum kok-saghyz". Pfaf.org. Retrieved 2013-03-21.
5. ^ Thomas M. Lewinsohn (1991). "The geographical distribution of plant latex". Chemoecology 2 (1): 64–68. doi:10.1007/BF01240668.
6. ^ Joseph F. James (1887). "The milkweeds". The American Naturalist, 21: 605–615. doi: 10.1086/274519. JSTOR 2451222.
7. ^ J. E. Bowers (1990). Natural Rubber-Producing Plants for the United States. Beltsville, MD: National Agricultural Library. pp. 1, 3. OCLC 28534889.
8. ^ http://wedo.co.uk/community/what-is-a-latex-mattress.
9. ^ http://books.google.com/books?id=De9RUVtQ5TQC&pg=PA33&dq=artificial+polyisoprene+protein.
10. ^ http://www.mayoclinic.com/health/latex-allergy/DS00621/DSECTION=risk-factors.
11. ^ Helge B. Bode; Axel Zeeck; Kirsten Plückhahn; Dieter Jendrossek (September 2000). "Physiological and Chemical Investigations into Microbial Degradation of Synthetic Poly(cis-1,4-isoprene)". Applied and Environmental Microbiology 66: 3680–3685. doi:10.1128/aem.66.9.3680-3685.2000.

- Wikipedia 

What Happens When Your Body Has Vitamin C Deficiency?

Vitamin C is a water-soluble vitamin essential for cellular growth and tissue repair. Also known as ascorbic acid, this vitamin exhibits antioxidant properties, protecting the body from cellular and molecular damage due to free radicals. According to the University of Maryland Medical Center, many people may be mildly deficient in vitamin C, contributing to numerous health conditions including heart disease and high blood pressure. The best way to prevent vitamin C deficiency is by eating fruits and vegetables.

Vitamin C deficiency can contribute to numerous health conditions. Photo Credit Ablestock.com/AbleStock.com/Getty Images

Vitamin C and Collagen Formation

Vitamin C is essential for the synthesis collagen, an important structural component of connective tissue, cartilage, skin, tendons, ligaments and blood vessels. This essential nutrient promotes cellular growth, tissue repair and wound healing. Vitamin C deficiency inhibits collagen and cartilage synthesis, and may result in degenerative joint diseases in which your joints become painful and swollen. Weakened connective tissue, broken blood vessels, weakened blood capillaries and muscle stiffness are symptoms of vitamin C deficiency. That deficiency results in impaired wound healing, internal bleeding, swollen and bleeding gums, weakened tooth enamel and loose teeth.

Vitamin C and Immune Health

Vitamin C is a powerful and effective antioxidant that destroys oxygen free radical that cause cellular damage, accelerate the aging process and increase your risk for different types of cancers. It strengthens the immune system, protects against viral and bacterial infections, and maintains the integrity of the immune system by protecting white blood cells from oxidative stress and damage caused by free radicals. Early symptoms of vitamin C deficiency in adults include weakness, lethargy and irritability; later symptoms include decreased immune function, respiratory infection, weight loss, anemia and jaundice.

Vitamin C Deficiency Causes and Treatment

A diet poor in fresh fruits and vegetables is the most common cause of vitamin C deficiency. Fruits and vegetables lose two-thirds of their vitamin C content in the cooking and canning process. Smoking or exposure to secondhand smoke, as well as an immune overload, also deplete your body of vitamin C. Chronic diarrhea, alcohol consumption and anorexia also increase your risk of vitamin C deficiency. The best treatment for vitamin C deficiency is increasing your intake of fresh fruits and vegetables.

Dietary Sources and Recommendations

Vitamin C can be obtained from all fruits and vegetables. Strawberries, oranges, tomatoes, broccoli, mango, green peppers, kiwi, cabbage, red peppers and watermelon are excellent sources of vitamin C. Vitamin C is sensitive to light, heat and air, thus raw and uncooked fruits and vegetables contain the highest content of vitamin C. The dietary recommendation is 90 mg for adult males and 75 mg for adult women daily. Vitamin C supplements, which are usually taken two to three times a day, can help improve blood vessel dysfunction and capillary weakness caused by smoking.

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Lunch Ideas for a High Fat Low Carb Diet

Typical lunch ideas, such as sandwiches, pizza, chili and sushi, contain a large amount of carbohydrates. If you are on a low-carb diet, restrict grains, starchy vegetables, legumes, fruits and sugars. Base your meals on low-carb foods. Nonstarchy vegetables are low in carbs, yet are rich in vitamins, minerals, fiber and antioxidants. Each of your low-carb, high-fat meals should also include animal proteins from eggs, meat, poultry and fish and extra fats from coconut oil, full-fat salad dressings, full-fat cheese, olive oil, avocado and nuts.

A bunless burger wrapped in lettuce. Photo Credit rez-art/iStock/Getty Images

Chicken, Cheese and Avocado Salad

You can quickly put together a satisfying low-carb, high-fat salad for your lunch at home, school or work. Simply mix a generous amount of leafy greens with any of your favorite nonstarchy vegetables, such as cucumber, tomatoes, green onions, bell peppers and broccoli. Add 4 to 6 oz. of chicken, the slices from half or a whole avocado, depending on your appetite, and grated cheese. You can also throw in a handful of almonds or walnuts for extra fat. Drizzle your salad with a full-fat ranch salad dressing or make your own vinaigrette using extra-virgin olive oil, vinegar and seasonings.

Bunless Burger

If you don't have time to prepare your own lunch, you can easily convert a burger meal into a low-carb, high-fat lunch. Buy a meat patty that does not contain flour, sugar or other high-carb fillers. Ask to have your burger without the bun and sugary sauces. You can use mustard, mayonnaise, bacon, cheese, lettuce, pickles and tomatoes to garnish your burger. Skip the french fries and soft drinks and have a bottle of water and some greens instead. Use a fork and knife or use lettuce leaves to wrap your bunless burger. You may need to eat two to three bunless burgers, depending on their size and your appetite, to get enough energy.

Salmon Stir-Fry

Leftovers make a convenient and easy meal if you have time to cook extra servings of your dinner the previous night. If you are following a low-carb, high-fat diet, your leftovers should already have the right ratio for you. For example, you could prepare extra servings of a salmon stir-fry for dinner to have leftovers for the next day. Rice is high in carbs, but you can make fake rice using cauliflower instead. Cauliflower rice is tasty and will allow you to enjoy your stir-fry without worrying about the carbs. Make low-carb "rice" by grating raw cauliflower and then sauteing it in coconut oil with onions, carrot, broccoli, bok choy or mushroom. Add 4 to 6 oz. of cooked salmon, coconut milk and turmeric, curry, dried chili or other spices.

Frittata With Bacon and Asparagus

A frittata, which can easily be cooked within 20 to 30 minutes, makes an idea low-carb, high-fat meal. You can make your frittata ahead of time and bring it for lunch to reheat or enjoy cold. Prepare your frittata by beating eggs with cream, sea salt, freshly ground pepper, and seasonings. Add a handful of asparagus that you previously grilled with olive oil in the oven, bacon pieces, and a spoonful of Parmesan cheese. Cook in olive oil in a skillet until the bottom is cooked and finish under the grill in the oven until fully cooked. Use a skillet that is oven safe. You can serve your frittata with avocado slices or a salad of leafy greens with full-fat salad dressing.

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Can You Eat Sliced American Cheese on a Gluten-Free Diet?

Gluten is a protein found in certain grains like wheat, barely and rye. People with celiac disease or gluten sensitivity have to be careful to avoid all gluten in foods, especially those with "hidden" gluten. It is easy to find foods containing wheat by reading ingredients labels; however, many additives in processed foods may contain gluten from sources other than wheat.

Label reading is an essential skill for those needing to avoiding gluten. Photo Credit Creatas Images/Creatas/Getty Images

Gluten in Cheese

Natural aged cheeses made from real milk are usually gluten-free; however, some processed cheeses may contain gluten. American cheese is generally gluten-free, according to the Jackson Siegelbaum Gastroenterology website. Still, you should always check the ingredients label of the particular cheese you are purchasing. Avoid cheeses with vegetable gum or food starch, which are likely to contain gluten. Also, check the label for preservatives that are not defined as a gluten-free sources. If you are unsure whether a product contains gluten, check the manufacturer's website for additional information.

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Quercetin, Bromelain and Vitamin C

People take dietary supplements with the goal of improving or maintaining their health, particularly, quercetin, bromelain, and vitamin C. Quercetin is found in fruits and vegetables, and when ingested it acts as a histamine inhibitor. Bromelain is an enzyme that comes from pineapples and may reduce inflammation. Vitamin C is a water soluble vitamin necessary for the growth and repair of the body’s tissues including cartilage, bones and teeth. These three supplements are used to treat conditions such as asthma, allergies and cases of angioedema. Before starting a supplement regimen, consult with your health professional; especially if you are pregnant or have a preexisting health condition.

Oranges and other citrus fruits contain vitamin C.Photo Credit Martin Poole/Digital Vision/Getty Images

Asthma

Asthma, a disorder affecting the lungs, manifests as “sudden fits of wheezing, coughing or shortness of breath,” according to information from the University of Michigan Health System. Adding quercetin, bromelain and vitamin C may relieve asthma symptoms for some patients. Quercetin has an inhibiting action on the enzyme lipoxygenase, which may have a role in inflammation. Bromelain reduces the viscosity of mucus and vitamin C may reduce the likelihood of bronchial spasms.

Allergies

Taking the supplements quercetin, bromelain and vitamin C may help relieve allergy symptoms, according to Dr. Kathi Kemper from the Center for Integrative Medicine at Wake Forest University Baptist Medical Center. Kemper explains vitamin C acts as mild antihistamine and recommends taking quercetin and bromelain simultaneously. However, she urges allergy sufferers to contact their doctors before starting regimens of these supplements.

Angioedema

The supplements quercetin, bromelain and vitamin C are suggested by the University of Maryland Medical Center to relieve the symptoms of angioedema. This health condition, often caused by an allergic reaction, refers to swelling located in the tissues just underneath the skin, commonly around your eyes and lips. Although not proven conclusively, vitamin C may lower histamine levels, quercetin could reduce your allergic sensitivity and bromelain is used to reduce inflammation.

Prostatitis

Prostatitis is inflammation of the prostate caused by acute bacterial prostatitis, chronic bacterial prostatitis, chronic non-bacterial prostatitis, and prostadynia. Suggested supplements to treat the symptoms of prostatitis, according to the University of Michigan Health System, include quercetin, bromelain and vitamin C. UMHS says quercetin and bromelain may improve symptoms of chronic non-bacterial prostatitis. Taking vitamin C is speculated to change urine composition in such a way that inhibits the growth of the E. coli virus, the most common cause of chronic bacterial prostatitis.

Precautions

As with any dietary supplement, follow the directions on the label to reduce your risk for side effects. The University of Maryland Medical Center recommends avoiding bromelain if you have a citrus allergy or if you are taking anticoagulants, as it may increase the risk of bleeding. Also, vitamin C in high doses causes diarrhea.

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Low-Carb Healthy Choice Meals

Low-carbohydrate diets were largely popularized with the release of the Atkin's Diet in 2004. Low-carb diets limit foods high in carbohydrates -- including rice, fruits, breads, grains and starchy vegetables. This type of diet places an emphasis on foods high in protein and fat. Low-carb diets help you to lose water weight, increase your feeling of fullness and reduce the amount of calories you take in. The Food manufacturer Healthy Choice provides numerous low-carb meals.

Healthy Choice offers convenient low carb meals. Photo Credit Stockbyte/Stockbyte/Getty Images

Healthy Choice Cafe Steamers

The Mayo Clinic indicates that low-carb diets restrict your carbohydrate intake to between 50 and 150 g of carbs per day. Healthy Choice Steamers offer a healthy dinner choice that cooks in only 3.5 minutes. Healthy Choice Steamers offer a wide variety of food selections. Meals generally include meat, potatoes, vegetables and a sauce. Each dinner contains 18 g of carbs and 5 g of fiber. Meals contain 220 calories.

Soups

Healthy Choice offers a wide-variety of low-carb, low-calorie soups. Soup flavors include chicken tortilla, vegetable, chicken and rice, wedding soup, cheese tortellini and beef pot roast. Soups are low in fat, sodium and cholesterol, which helps to promote heart health. Soups are also good sources of protein. The chicken tortilla soup contains one serving of lean meat, a serving of vegetables and one serving of starches. There are 140 calories per serving with 23 grams of carbs, 9 g or protein and 6 g of dietary fiber. Health Choice soups come in a one-serving size microwavable container.

Complete Meals

Health Choice also offers a variety of complete meals that include your main entree, a full serving of vegetables and a healthy, real fruit dessert. These meals are good sources of fiber and protein while low in carbs. They are recommended by the American Heart Association. Meal choices include chicken parmigiana, meat loaf, beef tips portobello, chicken teriyaki, lemon pepper fish and golden roasted turkey breast. The chicken teriyaki meal contains two servings of lean meet, two servings of carbs, a serving of vegetables and one and a half servings of starches. There are 53 g of carbohydrates and 350 calories per meal. You will also find 19 g of protein and 5 g of fiber.

Frozen Treats

Healthy Choice also offers a way for you to indulge yourself without feeling guilty. Healthy Choice offers low-fat frozen treats that are a good source of calcium and low in carbohydrates. They include fudge bars, ice cream sandwiches, mocha swirl bars and sorbet and cream bars. A fudge bar contains 13 g of carbohydrates, which is the equivalent of one serving. There are 80 calories in one bar with 4 g of fiber and 3 g of protein.

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Is Margarita Mix Gluten Free?

If you have gluten intolerance, also known as celiac disease, you already know that you need to scrutinize labels of any products that might contain wheat, rye or barley. As little as one-eighth of a tsp. of the gluten protein found in these grains can set off a reaction. Many Margarita mixes contain gluten, but you also can find gluten-free Margarita mixes. Tequila, which is used to make a Margarita, doesn't contain gluten.

Margarita in a glass on a wooden table. Photo Credit pilipphoto/iStock/Getty Images

Labeling Wheat

Because wheat is one of the eight most-common food allergens, in addition to being a trigger for celiac sufferers, manufactured food products that contain wheat must include this information on their nutritional label. This makes it easy to discover when wheat is as an ingredient in Margarita mixes. The label might say wheat flour, wheat starch or hydrolyzed wheat protein.

Labeling Barley

Barley, on the other hand, may be present in any food product that lists “malt” as an ingredient. Avoid barley malt, malt vinegar, rice malt, malt extract, malt flavoring and malt syrup. A drink mix labeled gluten-free should not contain any of these ingredients.

Restaurant Margaritas

If you order a Margarita in a restaurant, don’t assume it’s gluten-free. Ask your server to verify that it is. Some restaurant chains list foods or drinks containing gluten on their websites or menus. Remember that mixing a drink using the same blender or spoon that was used to make a drink containing gluten, or handling a basket of chips containing gluten and then handling your glass, could contaminate your drink. Let your server know you have a gluten intolerance so that she’ll take extra care to avoid contaminating your drink.

Considerations

If you have gluten intolerance, reading labels can seem like a full-time job. But if it keeps you symptoms-free, it’s worth it. Don’t rely on manufacturers to be consistent from one year to the next. Just because a mix was gluten-free at one point doesn’t mean it will remain that way, so always read labels. If a mix contains no gluten but the label states that the product was made in the same factory or on the same equipment used for gluten-free products, avoid it.

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SAP

Sap is a fluid transported in xylem cells (vessel elements) or phloem sieve tube elements of a plant. These xylem cells transport water and nutrients throughout the plant.

Sap is not to be confused with latex, resin or cell sap, it is a separate substance, separately produced, and with different components and functions

Types of Sap

Saps may be broadly divided into two types: xylem sap and phloem sap.

Sap droplets of Sansevieria trifasciata

Xylem sap (pronounced /ˈzaɪləm/, consists primarily of a watery solution of hormones, mineral elements and other nutrients. Transport of sap in xylem is characterized by movement from the roots toward the leaves.

Over the past century, there has been some controversy regarding the mechanism of xylem sap transport; today, most plant scientists agree that the cohesion-tension theory best explains this process, but multiforce theories that hypothesize several alternative mechanisms have been suggested, including longitudinal cellular and xylem osmotic pressure, gradients, axial potential gradients in the vessels, and gel- and gas-bubble-supported interfacial gradients

Xylem sap transport can be disrupted by cavitation an "abrupt phase change [of water] from liquid to vapor" —resulting in air-filled xylem conduits. In addition to being a fundamental physical limit on tree height, two environmental stresses can disrupt xylem transport by cavitation: "increasingly negative xylem pressures associated with water stress, and freeze-thaw cycles in temperate climates.

Phloem Sap

Phloem sap (pronounced /ˈfloʊɛm/), consists primarily of sugars, hormones, and mineral elements dissolved in water. It flows from where carbohydrates are produced or stored (sugar source) to where they are used (sugar sinks).

The pressure flow hypothesis proposes a mechanism for phloem sap transport. although other hypotheses have been proposed. Phloem sap is also thought to play a role in sending informational signals throughout vascular plants. "Loading and unloading patterns are largely determined by the conductivity and number of plasmodesmata and the position-dependent function of solute-specific, plasma membrane transport proteins. Recent evidence indicates that mobile proteins and RNA are part of the plant's long-distance communication signaling system. Evidence also exists for the directed transport and sorting of macromolecules as they pass through plasmodesmata.

A large number of animals and all members of the single insect order "Hemiptera" (the half-wings), feed directly on phloem sap, and make it the primary component of their diet. Phloem sap is "nutrient-rich compared with many other plant products and generally lacking in toxins and feeding deterrents, [yet] it is consumed as the dominant or sole diet by a very restricted range of animals". This apparent paradox is explained by the fact that phloem sap is physiologically extreme in terms of animal digestion, and it is hypothesized that few animals take direct advantage of this because they lack two adaptations that are necessary to enable direct use by animals. These include the existence of a very high ratio of non-essential/essential amino acids in phloem sap for which these adapted Hemiptera insects contain symbiotic microorganisms which can then provide them with essential amino acids; and also insect "tolerance of the very high sugar content and osmotic pressure of phloem sap is promoted by their possession in the gut of sucrase-transglucosidase activity, which transforms excess ingested sugar into long-chain oligosaccharides. A much larger set of animals do however consume phloem sap by proxy, either "through feeding on the honeydew of phloem-feeding hemipterans. Honeydew is physiologically less extreme than phloem sap, with a higher essential:non-essential amino acid ratio and lower osmotic pressure," or by feeding on the biomass of insects that have grown on more direct ingestion of phloem sap.

Leafhoppers feeding on sap, attended by ants

Human Uses

Maple syrup is made from reduced sugar maple sap. The sap often is harvested from the Sugar Maple, Acer saccharum.

In some countries (e.g., Lithuania, Latvia, Estonia, Finland, Belarus, Russia)?harvesting the early spring sap of birch trees (so called "birch juice"), for human consumption is common practice; the sap can be used fresh or fermented and contains xylitol.

Preparations made from the sap of Aloe vera are widely used for their purported soothing, moisturizing, and healing properties. Aloe vera gel is also used as an ingredient in commercially available lotions, yogurt, beverages, and some desserts. Note, however, that so-called aloe products such as "aloes", "aloe gel" etc. are not generally true sap. They are largely distinct substances, different from each other and different from the true phloem and cellular saps. They also are produced in different cellular structures, much as other distinct materials such as latex and resin are produced in special vessels in various other species of plants

Certain palm tree sap can be used to make palm syrup. In the Canary Islands they use the Canary Island Date Palm while in Chile they use the Chilean Wine Palm to make their syrup called miel de palma.

References

1. ^ ^a b c Aslam Khan (1 January 2001). Plant Anatomy And Physiology. Gyan Publishing House. ISBN 978-81-7835-049-3. Retrieved 6 April 2013.
2. ^ Marschner, H (1983). "General introduction to the mineral nutrition of plants. Inorganic Plant Nutrition: 5–60. doi:10.1007/978-3-642-68885-0_2.
3. ^ Zimmerman, Ulrich (2002). "What are the driving forces for water lifting in the xylem conduit?". Physiologia 114 (3): 327–335. doi:10.1034/j.1399-3054.2002.1140301.x. PMID 1206025.
4. ^ Tyree, Melvin T. (1997). "The cohesion-tension theory of sap ascent: current controversies". Journal of Experimental Botany 48 (10): 1753–1765. doi:10.1093/jxb/48.10.1753.
5. ^ ^a b Sperry, John S.; Nichols, Kirk L.; Sullivan, June E; Eastlack, Sondra E. (1994). "Xylem Embolism in ring-porous, diffuse-porous, and coniferous trees of Northern Utah and Interior Alaska. Ecology 75 (6): 1736–1752. doi:10.2307/1939633
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