Rhododendron arboreum is the national flower of Nepal. Most types of rhododendron have fibrous root. Some types grow as epiphytes, or "air-plants" with aerial roots. They grow by supporting on the other plants and by collecting moisture and nutrients directly from the air. Rhododendron is also known as "rose tree" because it often produces flowers in trusses, just like some types of roses ("rodon" is Greek word for "rose" and "dendron" for "tree"). Fruit of rhododendron is dry capsule. Ripe fruit usually splits lengthwise to release seed.Pollen and nectar of some species of rhododendron contain toxic substance called grayanotoxin that can induce poisoning of humans and animals. Horses are especially sensitive to this type of toxin. Rhododendron can survive up to 100 years under optimal environmental conditions. Medical studies showed that flavonoids, phenolic compounds and saponins extracted from rhododendron have anti-inflammatory (prevent inflammation) properties. They also act beneficially on the function of liver. Rhododendron maximum is the state flower of West Virginia. This species of rhododendron is imprinted on the flag of West Virginia.