Of the forma of Hibiscus Syriacus, national flower, a dozens of them have been recommended for landscape treess. To find out the highly resistant forma, 13 forma of Shrub al thea were fumigatedqr with $SO_2$ in phytotron and their visible injury was observed. Visible injury of Shrub al thea forma was spread on the vein in the shape of spot and diffused to whole leaf with wilting. The injury colors of forma were generally dull bluish green, dark grayish green. The tolerant forma to $SO_2$ were Sanchunyeo, Saeachim, Sulag and the highly sensitive forma were Lusi, Youngkwang. Therefore, Sanchunyeo, Saeachim and Sulag were recommeneded to plant in polluted areas.