Called The Queen of Hill Stations, Udhagamandalam - better known as Ooty—is the most popular hill station in the south. Nestled deep within the Nilgiri hills, Ooty is also known as The Blue Mountains, a reference to both the blue smoky haze given off by the eucalyptus trees that cover the area, and to the kurunji flower which blooms every 12 years, giving the slopes a bluish tinge. Lofty mountains, great lakes, dense forests, sprawling grasslands, miles of tea gardens and eucalyptus trees greet visitors to Ooty. The Government Rose Garden is situated on the slopes of the Elk Hill. Today this garden has the largest collection of roses in the country with over 17,000 varieties. Hybrid Tea Roses, miniature roses, Floribunda, Ramblers, and roses of unusual colors like black and green are all planted in the park. The 22-acre Ooty Botanical Gardens was laid out in 1847 and is open to the public as a park. The Botanical Garden is lush, green, and well-maintained. A flower show, along with an exhibition of rare plant species, is held every May. The garden has a 20-million-year-old fossilized tree and a variety of flora, ranging from rare trees (like the cork tree, the paper bark tree and the monkey puzzle tree), to flowering bushes and plants, ferns and orchids.