Boxwood.

The leafy, evergreen yellow poplars of the four seasons are common garden ornamental trees. Because its leaves have leather, the skin cells have a thicker layer, so sulfur dioxide, chlorine gas, hydrogen sulfide, hydrogen fluoride and other toxic gases have a strong resistance, as well as the ability to absorb toxic gas, purifying the air. Its chlorine absorption accounts for the second of nine plants with strong anti-fouling capacity.

Huang Yang, also known as "Guazi Huangyang", more variants, belong to Huang Yangke, evergreen shrubs or small trees, up to 6 meters high. Stems have four prisms, leaves have leather, round inverted egg shape, the top is slightly dented or blunt head, the surface is dark green, the leaf back pale. Small yellow flowers bloom in spring, clustered in the leaves.

yang is native to the central provinces of China, and is now cultivated everywhere. Yellow poplars grow extremely slowly, with a tree diameter of only 10 cm in 1980 and 1990. There is an ancient yellow poplar tree in front of the Temple of Guangfust in Suzhou, which is said to be 700 years old, but only 10 meters high and has a chest diameter of only 30 cm, so as the saying goes, "Millennium is not big yellow poplar".

yellow poplars are resistant to pruning, mostly as side hedges, or planted into flower beds and various geometric hedges. In Our country's classical garden, it is also used to tie into the image of lions, cranes and animals. Huang Yang's wood is tough and dense, which can be used for carving crafts and making wood combs.