Boron deficiency is rather rare in trees and shrubs but has been observed regularly in Chinese hibiscus (Hibiscus rosa-sinensis). Symptoms appear on the new growth as small, upwardly cupped or puckered, dark green, brittle leaves with short internodes (Figs. 20-21). It may result in a rosette effect or even shoot die-back (Fig. 22). Boron deficiency is caused by leaching on sandy soils, but by drying or high pH on other soil types.