Calycanthus is a plant genus that is part of the Calycanthaceae family. It contains a couple of species of deciduous shrubs that are native to North America. The plants feature unique flowers that have strap-like petals and aromatic foliage. Landscapers utilize this group of plants as a fence line shrub or as a background for a perennial garden. Some varieties in this genus are susceptible to fungal diseases.
The genus name is derived from the Greek words caly and anthus, which translate to "the calyx" and "a flower," respectively. Commonly, the plants in this genus are called allspice or sweetshrub. Some species have variations of the common name. For example, Calycanthus floridus is also called the Carolina allspice or the eastern sweetshrub. Calycanthus occidentalis is referred to as the California sweetshrub or the western sweetshrub.
Two species in this genus that are commonly cultivated are located in the eastern and western United States. Calycanthus floridus is generally found from Pennsylvania to Kentucky and south to the Florida panhandle. On the west coast, Calycanthus occidentalis is native to California. The plants typically grow at the edges of woods and at the banks of streams.
The flowers of this genus are exotic and fragrant. C. floridus blooms from April to July, featuring dark red flowers with numerous overlapping petals. C. occidentalis produces red, pink, or brown flowers from April to October. Typically, the flowers are about 3 inches (7.6 cm) across, and each bloom lasts one to two days.
C. floridus generally grows 6 to 12 feet (1.8-3.6 m) in height and has a rounded form. The multiple stems feature dark green, glossy leaves that are scented. The leaves become yellow in the fall and drop before the winter.
Usually, C. floridus is grown in loamy, humus-rich soil that is moist. It can adapt to inadequate soil conditions, but the plant may not grow as tall. For optimum development, it is recommended to plant C. floridus in a partly shaded to fully shaded area. Generally, the more sunlight exposure, the shorter the plant will be.
C. floridus is very resistant to disease and insect problems, but C. occidentalis is prone to leaf spot and powdery mildew. Leaf spot is a fungal disease, and it produces brown, red, or black spots on the leaves. Powdery mildew is caused by a fungus as well, and the symptoms include white to gray fuzzy patches on the surface of leaves and shoots.