Acorus is a plant genus that is part of the Acoraceae family. It consists of several monocot (single seed leaf) flowering plants that are native to the southeastern United States and the northern and eastern portions of Asia. Most of the species in the acorus genus feature tall grass-like leaves that surround a spadix, which is a fleshy spike covered with tiny flower clusters. Some species in the genus, including Acorus calamus, have been cultivated for hundreds of years for their medicinal uses, particularly for eye problems. In fact, the name "acorus" is believed to be derived from the Greek word coreon, which refers to the pupil of the eye.
The acorus genus consists of hemicryptophytes, which are perennial plants with buds that overwinter at the soil surface, and geophytes, which are perennial plants with buds that overwinter underground. Both feature a spadix that is 1.5-4.0 inches (4-10 cm) long and leaves which grow to 5 feet (about 1.5 m) in length. Most species have green leaves with cream colored veins and an aromatic scent. The chemical responsible for the fragrance of the leaves is asarone, which is an ether that is considered toxic to pests.
Most of the plants in the acorus genus grow near shallow bodies of water in wetlands and marshes. The banks of streams and lakes provide adequate conditions for this genus of plant to thrive. Typically, it requires extremely moist soil and full sunlight to produce vibrant foliage. It is possible to grow this genus in an aquarium, if it is properly designed. Usually, the smaller varieties of acorus are grown in aquatic containers, while the larger varieties are typically planted at the margins of a pool or in a bog garden.
Since an abundant amount of water is required in the acorus growing medium, there is an increased risk of fungal infection. Root rot in particular can cause severe damage to the plant. It is typically caused by a fungus that multiplies and spreads in the cool, moist soil. Usually, the fungus attacks the root hairs, which prevents the absorption of nutrients from the soil. As a result, the leaves become yellow and eventually drop.
Another fungal infection that targets this genus of plants is rust. Plant rust is characterized by reddish-brown specks and bumps that develop on leaves and stems. The best way to treat the fungal infection is to remove the diseased leaves and apply fungicide.