Trunkline Magazine (Louisville Zoo) Trunkline Magazine: September 2017 - Page 22

GARDEN TALK A Tree as Old as Louisville During this colorful time of year, many guests come to the Zoo not only to see our precious animal ambassadors but also to enjoy the autumn beauty of our accredited botanical garden. Traveling along the paths of the Gorilla Forest exhibit, you have probably walked beneath one of the most impressive specimens in our botanical collection. This tree, a massive bur oak, Quercus macrocarpa, casts a silent, sweeping presence over those lucky enough to pass under its branches. The size of our bur oak denotes that this is an old tree, but how old is it? This tree existed long before the Louisville Zoo opened in 1969; in fact, it was about 150 years old when the Zoo opened! From measurements taken of the tree, it is estimated to be about 217 years old — meaning it would have first sprouted in the year 1800. For reference, the city of Louisville was only 22 years old when this tree first germinated from an acorn. When the tree was just a sapling in 1808, the famous ornithologist, John James Audubon, was watching the now extinct passenger pigeon blanket the sky in flocks of millions of birds. Why is it called a bur oak? Bur oaks produce very large acorns that are almost completely covered by the cap of the acorn and have a uniquely fringed edge on the acorn cap. The scientific name, Quercus macrocarpa, refers to two dif- ferent points about the tree. The genus Quercus is Latin for “oak tree” and the species name macrocarpa comes from the Greek words macro meaning “large” and carpa meaning “fruit” in reference to the large acorn size. Bur oaks grow naturally throughout much of the north- central United States, the eastern Great Plains and southern Canada. Native to rich bottom land, bur oaks are tough and adaptable. They are cold hardy, tolerate drought and grow best in full sun. They are also more tolerant of urban condi- tions than most oaks. This oak spec Y\ܛX[Hܛ $  [][X\[H^YY L  ܈[ܙK]\H[Y \XY[[Yܛۈ][ܛ  YKZHY[YHوH[\\]H]][[X]\YB[HHYXYH]H\X\ۋ[H[x&\B\KZHHX][\HZ\ݚ[H&\\Hۈ8'YHقYx'H[\[]YYܞKY[Hۛ•[Hܚ[Hܙ\^X]\Z[[ X]][ۜ\HZ[ۈZ[و\XYۚYX[YKۙHو\\[ܚ]Y\\X[B ^YX\[\ZYH[Y[Y[Y[œX[ۋ\\H\[\HYH[[ܛ[YHۛX[]\ܛ[[\Y[Hܛ[ \[\Y[XX]H[H\YY]^BHHYK8(Z\ݚ[H[[H8([ M