sumac or sumach, common name for some members of the Anacardiaceae, a family of trees and shrubs native chiefly to the tropics but ranging into north temperate regions and characterized by resinous, often acrid, sap. The sap of certain of these plants—especially poison ivy and related species of the New World genus Toxicodendron—contains an essential oil that can cause dermatitis. In these and other species the sap is also a major source of tannin, e.g., the quebracho tree of Paraguay, the lacquer tree of SE Asia, and the terebinth or turpentine tree and the mastic trees of the Mediterranean area. The pistachio, cashew, and mango provide important foods both for local consumption and for trade. The resin content is responsible for the acid taste of mango and cashew fruits and of the oil (sometimes extracted) in pistachio and cashew nuts. The true sumacs belong to the genus Rhus; some botanists include the poison ivy, poison oak, and poison sumac in that genus. Several species of sumacs are native to North America, usually in dry areas, and are noted for their brilliant autumn coloration. The common staghorn sumac (R. typhina) of the Eastern states is one of the species whose fruit is used in wine making and for medicinal purposes. Some sumacs—e.g., the Sicilian sumac (R. coriara) of S Europe—are cultivated for their tannin. Sumacs are also cultivated as ornamentals, e.g., the smoke tree (Cotinus coggygria) of S Eurasia, whose bark is sometimes used for a dye, and the pepper tree, or Peruvian mastic (Schinus molle), of the American tropics. The latter, with its drooping branches and red fruits, is a favorite avenue ornamental in S California; however, it is highly susceptible to black scale, a disease destructive to fruit trees, and hence must be destroyed in areas where there are citrus groves. Sumac is classified in the division Magnoliophyta, class Magnoliopsida, order Sapindales, family Anacardiaceae.

Sumac (or /ˈs(j)uːmæk/; also spelled sumach) is any one of approximately 250 species of flowering plants in the genus Rhus and related genera, in the family Anacardiaceae. The dried berries of some species are ground to produce a tangy purple spice often used in juice.

Sumacs grow in subtropical and warm temperate regions throughout the world, especially in North America.

Sumacs are shrubs and small trees that can reach a height of 1-10 meters. The leaves are spirally arranged; they are usually pinnately compound, though some species have trifoliate or simple leaves. The flowers are in dense panicles or spikes 5-30 cm long, each flower very small, greenish, creamy white or red, with five petals. The fruits form dense clusters of reddish drupes called sumac bobs.

Sumacs propagate both by seed (spread by birds and other animals through their droppings), and by new sprouts from rhizomes, forming large clonal colonies.

Cultivation and uses

The drupes of the genus Rhus are ground into a deep-red or purple powder used as a spice in Middle Eastern cuisine to add a lemony taste to salads or meat; in the turkish cuisine e.g. added to salad-servings of kebabs and lahmacun. In North America, the smooth sumac (Rhus glabra), and the staghorn sumac (Rhus typhina), are sometimes used to make a beverage, termed "sumac-ade" or "Indian lemonade" or "rhus juice". This drink is made by soaking the drupes in cool water, rubbing them to extract the essence, straining the liquid through a cotton cloth and sweetening it. Native Americans also used the leaves and berries of the smooth and staghorn sumacs combined with tobacco in traditional smoking mixtures.

Species including the fragrant sumac (Rhus aromatica), the littleleaf sumac (R. microphylla), the skunkbush sumac (R. trilobata), the smooth sumac and the staghorn sumac are grown for ornament, either as the wild types or as cultivars.

The leaves of certain sumacs yield tannin (mostly pyrogallol), a substance used in vegetable tanning. Leather tanned with sumac is flexible, light in weight, and light in color, even bordering on being white.

Dried sumac wood is fluorescent under long-wave UV light.

Mowing of sumac is not a good control measure as the wood is springy resulting in jagged, sharp pointed stumps when mowed. The plant will quickly recover with new growth after mowing. See Nebraska Extension Service publication G97-1319 for suggestions as to control.

Taxonomy

At times Rhus has held over 250 species. Recent molecular phylogeny research suggests breaking Rhus sensu lata into Actinocheita, Baronia, Cotinus, Malosma, Searsia, Toxicodendron, and Rhus sensu stricta. If this is done, about 35 species would remain in Rhus. However, the data is not yet clear enough to settle the proper placement of all species into these genera.

Selected species

Africa: Rhus acocksii Moffett Rhus albomarginata Sond. Rhus angustifolia L. Rhus batophylla Codd Rhus baurii Schonl. Rhus bolusii Sond. ex Engl. Rhus burchellii Sond. ex Engl. Rhus carnosula Schonl Rhus chirindensis Bak.f. Rhus ciliata Licht. ex Schult. Rhus crenata Thunb. Rhus cuneifolia L. Rhus dentata Thunb. Rhus discolorE.Mey. ex Sond. Rhus dissecta Thunb. Rhus divaricata Eckl. & Zeyh. Rhus dracomontana Moffett Rhus dregeana Sond. Rhus dura Schonl. Rhus engleri Britt. Rhus erosa Thunb. Rhus fastigiata Eckl. & Zeyh. Rhus gerrardii (Harv. ex Engl.) Diels. Rhus glauca Thunb. Rhus gracillima Engl. Rhus grandidens Harv. ex Engl. Rhus gueinzii Sond. Rhus harveyi Moffett Rhus horrida Eckl. & Zeyh. Rhus incisa L.f. Rhus kirkii Oliv. Rhus keetii Schönl. Rhus krebsiana Presl ex Engl. Rhus laevigata L. Rhus lancea L.f. (syn. Searsia lancea) Rhus leptodictya Diels. Rhus longispina Eckl. & Zeyh. Rhus lucens Hutch. Rhus lucida L. Rhus macowanii Schönl. Rhus magalismontana Sond. Rhus maricoana Moffett Rhus marlothii Engl. Rhus microcarpa Schonl. Rhus montana Diels Rhus natalensis Bernh. ex Krauss Rhus nebulosa Schonl. Rhus pallens Eckl. & Zeyh. Rhus pendulina Jacq. Rhus pentheri Zahlbr. Rhus pondoensis Schönl. Rhus populifolia E.Mey. ex Sond. Rhus problematodes Merxm. & Roessl. Rhus pterota Presl Rhus pygmaea Moffett Rhus pyroides Burch. Rhus quartiniana A. Rich. Rhus refracta Eckl. & Zeyh. Rhus rehmanniana Engl. Rhus rigida Mill. Rhus rimosa Eckl. & Zeyh. Rhus rogersii Schonl. Rhus rosmarinifolia Vahl Rhus rudatisii Engl. Rhus scytophylla Eckl. & Zeyh. Rhus sekhukhuniensis Moffett Rhus stenophylla Eckl. & Zeyh. Rhus tenuinervis Engl. Rhus tomentosa L. Rhus transvaalensis Engl. Rhus tridactyla Burch. Rhus tumulicola S.Moore Rhus undulata Jacq. Rhus volkii Suesseng. Rhus wilmsii Diels. Rhus zeyheri Sond.

Asia: Rhus chinensis (Chinese sumac) Rhus hypoleuca Rhus javanica Rhus punjabensis (Punjab sumac) Rhus verniciflua (syn. Toxicodendron vernicifluum, lacquer tree) Rhus succedanea (syn. Toxicodendron succedaneum)Australia, Pacific: Rhus taitensis GuilleminMediterranean region: Rhus coriaria (Tanner's sumac) Rhus pentaphylla Rhus tripartitaEastern North America: Rhus aromatica (fragrant sumac) Rhus copallina (winged or shining sumac) Rhus glabra (smooth sumac) Rhus lanceolata (prairie sumac) Rhus michauxii (Michaux's sumac) Rhus typhina (staghorn sumac) Rhus toxicodendron (syn. Toxicodendron radicans, poison ivy) Rhus vernix (syn. Toxicodendron vernix, poison sumac)Western North America: Rhus choriophylla (Mearn's sumac), Arizona, New Mexico Rhus laurina (syn. Malosma laurina, laurel sumac). Rhus integrifolia (lemonade sumac) Rhus glabra (smooth sumac) Rhus microphylla (desert sumac, littleleaf sumac) Rhus ovata (sugar sumac) Rhus trilobata (skunkbush sumac) Rhus virens (evergreen sumac)Mexico and Central America: Rhus muelleri (Müller's sumac); northeast MexicoPacific Ocean: Rhus sandwicensis A. Gray (Neleau); Hawaii, endemic.

Rhus sp. nov. A is a so-far unpublished species, endemic to Yemen. Its natural habitats are subtropical or tropical dry forests, subtropical or tropical dry shrubland, and rocky areas. It was given the status of "vulnerable" by the IUCN Red List.

See also

• List of Southern African indigenous trees
• Za'atar

References

Notes

Bibliography

• RO Moffett. A Revision of Southern African Rhus species FSA (Flora of South Africa) vol 19 (3) Fascicle 1.
• Schmidt, E., Lotter, M., & McCleland, W. (2002). Trees and Shrubs of Mpumalanga and Kruger National Park. Jacana. ISBN 1-919777-30-X.

External links

• Germplasm Resources Information Network: Rhus
• Global Biodiversity Information Facility portal: Rhus

Stanford University Mathematics Camp, or SUMaC, is a competitive summer mathematics program for rising high school juniors and seniors around the world. The camp lasts for 4 weeks, usually from mid-July to mid-August. It is based on the campus of Stanford University.

Like the Ross Program at Ohio State and the PROMYS program at Boston University, SUMaC does not put emphasis on competition-math preparations but focuses instead on advanced undergraduate math topics.

History

SUMaC was founded in 1995 by Professors Rafe Mazzeo and Ralph Cohen of the Stanford Mathematics Department and is currently directed by Prof. Mazzeo, Dr. Pierre Albin, and Dr. Rick Sommer. Dr. Sommer was an Assistant Professor in the Stanford Mathematics Department and is currently a Deputy Director of the Education Program for Gifted Youth (EPGY), at Stanford. He designed the Program I course and has been teaching versions of it since the first SUMaC in 1995. The Program II course is designed and taught by Prof. Rafe Mazzeo. In recent years, Dr. Pierre Albin has also started teaching Program II with Prof. Mazzeo. Dr. Pierre Albin currently teaches at MIT.

Programs

• Program I investigates non-constructibility in geometry, classification of patterns in two dimensions, error-correcting codes, cryptography, and the analysis of the Rubik's cube. The mathematics that is central to solving these problems comes from the areas of abstract algebra and number theory.
• Program II contains an introduction to selected topics in combinatorial, differential, and algebraic topology. The program emphasizes developing ideas from, and problems in, geometric topology where methods from abstract algebra and calculus have proven to be effective tools.

Other activities

During the camp, there are frequent guest lectures given by internationally renowned mathematicians. These talks are in the areas of current mathematical research. Ravi Vakil, a current Stanford mathematics professor and a 4-time Putnam Fellow, talked to the students in 2007. Also in 2007, Tyson Mao, one of the best cube solvers in the world, taught SUMaC students how to solve the Rubik's cube. Other speakers in 2007 included Drs. Kay Kirkpatrick (MIT), Ted Shifrin (University of Georgia), and Pete Storm (Stanford). Students at SUMaC also engage in a variety of sports activities during their free time. Such sports include basketball, tennis, badminton, table tennis, and ultimate.

Teaching assistants and counselors

Most of the SUMaC residential counselors and teaching assistants are Stanford mathematics graduate students and undergraduate math majors. SUMaC usually has a 1-to-4 ratio of staff to students, with most of the teaching assistants serving in the role of live-in counselors. Many of the SUMaC teaching assistants and counselors return from previous years, and some attended SUMaC in high school.

Residence

SUMaC students have traditionally been housed in Synergy , a small Stanford-student residence that is a famously vegitarian co-op during the academic year, though there has been years when students lived in Κappa Αlpha (KA). Each student has a roommate, and the floors are divided by sex. Dining takes place at a separate dining hall shared by other summer youth programs at Stanford.

Other Facts

SUMaC was the backdrop for Justina Chen Headley's book Nothing But the Truth (and a Few White Lies), a teen novel about a half-Taiwanese girl who finally finds her identity at the math camp.

External links

• SUMaC: Official Site
• Synergy House at Stanford: Official Site
• "Nothing But the Truth" on Amazon.com