Spiraea dasyantha

Spiraea tosaensis

Flower name
Spiraea dasyantha
Scientific name
Spiraea tosaensis
Alias土佐下野, とさしもつけ
Place of originJapan
Place of floweringGarden, Specific area
Flowering seasonApril, May

What is Spiraea dasyantha

Tosa shimotsuke (Tosa shimotsuke, scientific name: Spiraea tosaensis) is a deciduous shrub in the family Rosaceae, native to Kochi and Tokushima prefectures in Japan. It grows naturally along the Shimanto River in Kochi Prefecture and along the Nakagawa Rivers and Katsuura Rivers in Tokushima Prefecture.
The trunk grows to 1 to 2 meters tall. It produces many hemispherical white flowers similar to those of Spiraea cantoniensis in spring in diffuse inflorescences extending from the stem tips.

Spiraea
The following is a list of the members of the genus Spiraea.
The genus name "Spiraea" means "spiral" in Latin. The word "spiral" refers to the spiral shape of the leaves, which are arranged in a spiral so that they do not overlap each other when they are attached to the branches.

Meaning of the species name
The species name "tosaensis" is composed of "tosa" (Tosa) and "ensis" (a suffix indicating a place name), meaning "of Tosa.

Origin of the flower name
The name "Tosa shimotsuke" comes from the fact that it was first discovered in Kochi Prefecture. It is also called "Tosa" because Kochi Prefecture used to be the Tosa Domain.

Flowers similar to Tosa-shimotsuke
A similar flower is Ibuki-simotsuke (scientific name: Spiraea dasyantha), which was first discovered on Mount Ibuki.

Characteristics of Ibuki-simotsuke
The leaf shape is inverted lanceolate, small and elongated. The stamens of the flowers are shorter than the petals.

Common name: Tosa shimotsuke (scientific name: Spiraea tosaensis), native to Kochi and Tokushima prefectures in Japan, habitat distribution: sunny riverside rocky areas, life form: cold and heat tolerant deciduous shrub, height: 1.5 m, tree form: Leaf: 0.2-0.5 cm, Petiole: thin papery, Leaf color: green (surface), powdery white (underside), Leaf shape: inverted lanceolate, Leaf length: 1.5-5 cm, Leaf width: 0.5 cm, Leaf margin: entire or obtuse serrate at the tip, Phyllotaxy: alternate, bisexual, radially symmetric, Inflorescence form: paniculate, Inflorescence length: 2 to 3 cm, Flower color: white, Flower diameter: 0.7 cm Diameter: 0.7 cm, Flowering season: April to May, Number of petals: 5, Number of sepals: 5, Number of stamens: 20, Fruit: aggregate fruit (5 aggregates), Fruit length: 0.3 cm, Fruiting season: July to August, Use: Garden planting.