The Acoraceae family consists of perennial herbs with rhizomes. The leaves emerge from the rhizome in a skirt-like fashion, arranged in two longitudinal rows, and are linear or sword-shaped. The basal flower stalk is erect and bears a single spadix with a single leaf-like bract. The inflorescence has numerous flowers, which are bisexual or triperen, with six perianth segments arranged in two whorls, six stamens, and one pistil. The fruit is a berry. It is widely distributed in the Northern Hemisphere, excluding arid regions from subtropical to subarctic areas, and consists of one genus and two species. There are also two species of the Acoraceae genus in Japan.
This article provides a comprehensive, field guide-style introduction to plants belonging to the Acorus family.
The basic information is based on the Kanagawa Prefecture Flora Survey Association (2018). Photos are replaced as better ones become available. While the identification is done by the author, please note that misidentifications may be corrected without notice.
No. 0167 Acorus gramineus
Perennial herb. Rhizomes are 5-8 mm in diameter. Leaves are slightly ascending, 20-50 cm long, and less than 6 mm wide. Flowers bloom in May and June. Flower stalks are about 10 cm tall. Spathes are leaf-like and 3-15 cm long. Spadix is 5-10 cm long and 3-5 mm wide. It grows in shady spring water areas and stream banks in the Castanopsis and Quercus zone. Distributed in Honshu, Shikoku, Kyushu; China, and India. A characteristic species of the Acorus gramineus community. A variety with narrow, short leaves and small inflorescences is called Acorus gramineus f. pusillus, which is planted in gardens and sometimes escapes cultivation.
No.0167.1 Acorus gramineus var. decoratus
A variety of Acorus gramineus with variegated leaves.
References
Kanagawa Prefecture Flora Survey Association. 2018. Kanagawa Prefecture Flora 2018 (Electronic Edition). Kanagawa Prefecture Flora Survey Association, Odawara. 1803pp. ISBN: 9784991053726
