Stromanthe sanguinea (Stromanthe thalia)Stromanthe has striking spearhead leaves with purple undersides. It can grow outside in a humid tropical climate, but needs light shade in the afternoon and must be protected from high winds. The soil should be kept moist at all times, but never waterlogged as the plant is susceptible to root rot. Under ideal growing conditions, Stromanthe sanguinea will reach 46 ft.