Pterostyrax hispida

Flower name
Pterostyrax hispida
Scientific name
Pterostyrax hispida
Alias大葉麻殻, イモノキ, タニアサ
Place of originJapan
Place of floweringGarden, Botanical Gardens, Cemetery & Temple
Flowering seasonJune

What is Pterostyrax hispida

Pterostyrax hispida (Japanese name: Ōba-asagara) is a deciduous tall tree native to Japan, belonging to the genus Pterostyrax of the family Styracaceae (Silver-bell family).
It is also known by other names such as Imonoki (“Potato tree”) and Tani-asa (“Valley Asa”).

Differences between Ōba-asagara and Asagara
Pterostyrax hispida (Ōba-asagara) and Pterostyrax corymbosus (Asagara) are similar species.
Key differences include:

Ōba-asagara: Inflorescences and fruits hang vertically, leaves are large with a flat base, margins are nearly entire, and the underside is white.

Asagara: Inflorescences and fruits spread horizontally, leaves are smaller with a wedge-shaped base, leaf margins have fine needle-like teeth, and the underside is green.

Left: Pterostyrax hispida (Ōba-asagara), Right: Pterostyrax corymbosus (Asagara)

Common name: Ōba-asagara
Scientific name: Pterostyrax hispida
Synonyms: Asagara, Imonoki, Tani-asa
Classification: Kingdom Plantae, Angiosperms, Eudicots, Order Ericales, Family Styracaceae, Genus Pterostyrax, Species P. hispida
Origin: Japan
Habitat: From Honshu to Shikoku and Kyushu, in mountain valleys
Growth form: Deciduous tall tree
Height: 10 m
Trunk color: Light brown
Leaf arrangement: Alternate
Leaf shape: Oblong
Leaf length: 10–20 cm, tip short and pointed
Leaf margin: Nearly entire, with very small needle-like serrations
Leaf color: Green (upper), white with raised veins and hairs on veins (underside)
Flowering season: June
Inflorescence type: Elongated raceme hanging down vertically
Flower color: White
Flowers per cluster: Many
Stamens: 1
Fruit season: September to October
Fruit shape: Inverted egg-shape with 10 ridges, densely covered with light brown hairs
Fruit diameter: 0.7 cm
Seed dispersal: Wind
Uses: Chopsticks
Notes: Not eaten by deer

Origin of the Japanese Name
The name "Asagara" refers to the fact that the wood is brittle and peels into threads,
resembling ogara, the peeled stalk of hemp used to make incense sticks or ceremonial chopsticks for the Bon Festival.
Related pages:
Pterostyrax hispida
Pterostyrax corymbosus
Styrax obassia (Hakuunboku)

■ Related page
Pterostyrax corymbosus
Hakunboku(scientific name: Styrax obassia)