Sedum lineare, a kind of tough evergreen succulents are seen planted on rooftops of student dormitory buildings at Zhengzhou Sias University in Zhengzhou, Central China’s Henan province. (Photo: China News Service/ Zheng Yan)

Sedum lineare, a kind of tough evergreen succulents are seen planted on rooftops of student dormitory buildings at Zhengzhou Sias University in Zhengzhou, Central China’s Henan province. (Photo: China News Service/ Zheng Yan)

Sedum lineare, a kind of tough evergreen succulents are seen planted on rooftops of student dormitory buildings at Zhengzhou Sias University in Zhengzhou, Central China’s Henan province. (Photo: China News Service/ Zheng Yan)

Sedum lineare, a kind of tough evergreen succulents are seen planted on rooftops of student dormitory buildings at Zhengzhou Sias University in Zhengzhou, Central China’s Henan province. (Photo: China News Service/ Zheng Yan)

Sedum lineare, a kind of tough evergreen succulents are seen planted on rooftops of student dormitory buildings at Zhengzhou Sias University in Zhengzhou, Central China’s Henan province. (Photo: China News Service/ Zheng Yan)