Aphananthe aspera: Muku Tree
Updated: Jun 2, 2021
Common English Name: Muku Tree
Japanese Name (Katakana): ムクノキ
Japanese Name (Kanji): 椋の木
Height: 15 - 20 meters
Native to Japan, Korea, Taiwan, China, and Vietnam, Aphananthe aspera is not exactly known for its flashiness. Nor are its closest relatives - its small genus (in the family Cannabaceae, which also includes hemp, hops, and hackberries), named Aphananthe, comes from the Greek for “obscure/unseen flower.” The Japanese name ムクノキ (Mukunoki) is a bit more charitable, and nods to the tree’s ecological role as a contributor to biodiversity. Though the name origin remains contested, it is often related to the Muku bird (the White-cheeked starling, Sturnus cineraceus, ムクドリ “Mukudori”) which visits the tree for its edible fruits. And it is far from the only bird that does so: other species, particularly the dusty thrush (Turdus eunomus, ツグミ) and the brown-headed thrush (Turdus chrysolaus, アカハラ), are frequent visitors to these trees. For many bird species, it is a valuable food source for seasonal migration and winter survival. Tasting similar to raisins, apricots, or dried persimmons, these berries also used to be a popular snack for Japanese children.
Historically, fossil pollen records (which help scientists reconstruct past environmental conditions) have shown both Aphananthe aspera and Celtis sinensis (also of the family Cannabaceae) dominating the broad-leaved forests of the Kyoto Basin 5,000 - 8,500 years ago. The leaves of the two species can be difficult to distinguish; however, the leaves of Aphananthe aspera have a notable sandpaper-y texture that can be used to differentiate the two (alongside other identification factors detailed below). Because of this unique trait, the leaves of Aphananthe aspera have been used as a natural sandpaper in the past.
Today, you can find Aphananthe aspera trees in hilly areas with moderate humidity and plenty of sunshine in Honshu, Shikoku, Kyushu, and Okinawa. They are also commonly planted in parks and along roadsides.
Leaves: Leaves alternate along the stem and are 4 - 10 cm long. Both sides of the leaf are covered in coarse hairs that feel like sandpaper. They will emerge in spring slightly later than other trees.
Bark: The bark is gray-brown with lighter-colored vertical streaks when young. When older, bark can peel off in vertical strips. Its wood has traditionally been used for construction and to make equipment.
Flowers and Fruit: This species bears flowers in April - May when the leaves emerge. The flowers appear in small, tight clusters and are not too noticeable. Fruits are black when ripe in October, edible, marble-sized, and attract a variety of bird species.
Celtis sinensis var. japonica has similar leaves to Aphananthe aspera. Here are some ways to tell the two species apart:
Aphananthe aspera leaves are sandpaper-y on both sides, while Celtis sinensis var. japonica leaves are smooth.
On Aphananthe aspera leaves, serration starts near the base of the leaf. On Celtis sinensis var. japonica leaves, serration starts about halfway up the length of the leaf.
The bark of Aphananthe aspera will have vertical streaks or appear vertically flaky; Celtis sinensis var. japonica bark is generally smooth with no such vertical markings.
A note about edible plants: Tokyo Naturalist does not recommend attempting to consume or prepare gathered nuts, fruits, leaves, or other materials without the guidance of an expert. The information provided here is meant to provide cultural and historical background on the uses of this species in Japan, and should not serve as a guide for gathering or preparation. We can not assume responsibility for the potential adverse effects of consuming improperly identified or prepared plants. Please exercise great caution and consult with an expert for more information.
Lin, Qin-Wen, et al. “The IUCN Red List of Threatened Species.” IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources., 12 June 2018, www.iucnredlist.org/species/147379708/147652809.
TABATA, Keizo, and Yukihiro MORIMOTO. "Regeneration Traits of Celtis sinensis Pers. and Aphananthe aspera (Thunb.) Planch. in a Created Urban Tree Plantation approximately 20 years after construction." Journal of Environmental Information Science 45 (2017): 1-8.
Field Guides Consulted:
Title: 葉っぱで見分け五感で楽しむ樹木図鑑 (Happa de miwake gokan de tanoshimu jumokuzukan)
Author: 林将之 (Hayashi Masayuki)
Publishing Date and Publisher: 2014, ナツメ社
Title: 樹皮・葉でわかる樹木図鑑 (Juhi・Hadewakaru jumokuzukan)
Author: 菱山忠三郎 (Hishiyama Chuzaburo)
Publishing Date and Publisher: 2011, 成美堂出版
Photography: Siri McGuire