Osmunda japonica, commonly known as Asian royal fern, is a deciduous fern native to moist woodlands and shaded stream banks in East Asia, including Japan, China, Korea, Taiwan, and far eastern Russia. It typically grows to a height of 24-36 inches (60-90 cm) with a similar spread. The Asian royal fern has a graceful, arching habit with bright green, lance-shaped fronds that are divided into numerous leaflets, giving it a delicate appearance. The fertile fronds are shorter and bear spore cases on the underside, while the sterile fronds resemble those of the closely related Osmunda regalis, or royal fern. This species does not flower but is valued for its lush foliage and the contrast between its fertile and sterile fronds.

The Asian royal fern is appreciated for its ornamental qualities and its ability to thrive in damp, shady garden spots where other plants might struggle. It is often used in woodland gardens, shaded borders, and as a naturalizing element in moist areas. This fern prefers consistently moist, humus-rich soil and can tolerate wet conditions, making it suitable for planting near water features or in bog gardens. It is also known for its air-purifying properties, notably its capacity to reduce formaldehyde levels indoors. While generally low-maintenance, it can be susceptible to crown rot if planted in poorly drained soils or overly wet conditions.CC BY-SA 4.0