Read the following text to answer question.

    Gardenia plants are popular for the strong sweet scent of their flowers. Gardenia is the national flower in Pakistan. In japan and China, the flower is called Kuchinashi (Japanese) and Thi zi (Chinese).

    Gardenia plants are evergreen shrubs. Their small trees can grow to 1 – 5 meters tall. The leaves are 5 – 50 centimeters long and 3 – 25 centimeters broad, dark green, and glossy with a leathery texture. The flowers are in small groups, white, or pale yellow, with 5 – 12 lobes (petals) from 5 – 12 centimeters diameter. They usually bloom in mid-spring to mid-summer. Many species have strong aroma.

    To cultivate gardenia as a house plant is not easy. This species can be difficult to grow because it originated in warm humid tropical areas. It demands high humidity and bright (not direct) light to thrive. It flourishes in acidic soil with good drainage and thrives on 20° – 23° C during the day and 15° – 16°C in the evening. Potting soils developed specifically for gardenias are available. It grows no larger than 18 inches in height and width when grown indoor. In climates where it can be grown outdoors, it can reach the height of 6 feet. If water hits the flowers, they will turn brown.

“… because it originated in warm … (paragraph 3, line 10)

The underlined word refers to ____.