Question: In which county is the botanical gardens of which, The Desert Garden Conservatory, is part ?

<P0-S0> The Huntington Library, Art Collections and Botanical Gardens (or The Huntington) is a collections-based educational and research institution established by Henry E. Huntington (1850–1927) and located in Los Angeles County in San Marino, California, on the western coast of the United States, and about 35 miles northeast of the Pacific Ocean. <P0-S1>  In addition to the library, the institution houses an extensive art collection with a focus in 18th and 19th-century European art and 17th to mid-20th-century American art. <P0-S2>  The property also includes approximately 120 acres of specialized botanical landscaped gardens, most notably the "Japanese Garden", the "Desert Garden", and the "Chinese Garden" (Liu Fang Yuan). <SEP> <P1-S0> The Huntington Desert Garden is part of The Huntington Library, Art Collections and Botanical Gardens in San Marino, California. <P1-S1>  The Desert Garden is one of the world's largest and oldest collections of cacti, succulents and other desert plants, collected from throughout the world. <P1-S2>  It contains plants from extreme environments, many of which were acquired by Henry E. Huntington and William Hertrich (the first garden curator) in trips taken to several countries in North, Central and South America. <P1-S3>  One of the Huntington’s most botanically important gardens, the Desert Garden brought together a group of plants largely unknown and unappreciated in the beginning of the 1900s. <P1-S4>  Containing a broad category of xerophytes (aridity-adapted plants), the Desert Garden grew to preeminence and remains today among the world’s finest, with more than 5,000 species in the 10 acre (4 ha) garden. <SEP> <P2-S0> The Desert Garden Conservatory is a large botanical greenhouse and part of the Huntington Library, Art Collections and Botanical Gardens, in San Marino, California. <P2-S1>  It was constructed in 1985. <P2-S2>  The Desert Garden Conservatory is adjacent to the 10 acre Huntington Desert Garden itself. <P2-S3>  The Garden houses one of the most important collections of cacti and other succulent plants in the world, including a large number of rare and endangered species. <P2-S4>  The 3000 sqft Desert Garden Conservatory serves The Huntington and public communities as a conservation facility, research resource and genetic diversity preserve. <P2-S5>  John N. Trager is the Desert Collection curator. <SEP> <P3-S0> The Walter Sisulu National Botanical Garden ("previously known as the Witwatersrand National Botanical Garden") is a 300 ha botanical reserve in Roodepoort near Johannesburg. <P3-S1>  Formally established in 1982, it is one of the youngest of South Africa's National Botanical Gardens, but the site where it is located has been popular with visitors for many decades before that. <P3-S2>  The garden is home to a well known pair of Verreaux's eagles that nest in the Roodekrans ridge which intersects the reserve. <P3-S3>  The garden has a restaurant, gift shop and nursery which sells South African native plants (the nursery closed March 2015). <P3-S4>  The Garden has been recognized as one of the most beautiful botanical gardens in the world.