Akebono azalea - Akebono azalea

A large deciduous shrub of the Ericaceae family (APG classification: Ericaceae). It is 2-6 meters tall, with smooth, light gray-brown bark and hairless branches. It has 5 whorled leaves at the ends of the branches, elliptical, 3-5 cm long, slightly pointed at both ends, and bristly at the edges. In April and May, before the leaves appear, pink flowers about 5 cm in diameter bloom at the ends of the branches. The pedicel has no glandular hairs, the corolla is 5-lobed, the lobes are broadly obovate, there are 10 stamens, and the filaments are hairless. The fruit is an elliptical capsule about 1.5 cm long that ripens brown and splits in October. It is distributed in the Kinki region and west of Honshu, Shikoku, and the mountainous areas of Kyushu.

The Akayashio variety resembles Akebonotsutsuji, but has many glandular hairs on the pedicel, and five of the ten stamens have fine hairs at the base of the filaments. It is distributed from Fukushima Prefecture south of Honshu, and the white-flowered variety is called Yukiyashio. In the southwestern part of Shikoku and in mountainous areas such as Mt. Ichifusa and Mt. Takakuma in Kyushu, there is the standard variety Tsukushi Akebonotsutsuji, which has glandular hairs on the pedicel and no hairs on the filaments. It is planted as a garden tree.

[Yoshio Kobayashi April 16, 2021]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

ツツジ科（APG分類：ツツジ科）の落葉大低木。高さ2～6メートルで樹皮は淡灰褐色、滑らかで枝に毛がない。葉は枝先に輪生状に5枚つき、楕円(だえん)形、長さ3～5センチメートルで両端はややとがり、縁(へり)に剛毛がある。4～5月、葉の出る前に枝先に径約5センチメートルの桃色花が開く。花柄に腺毛(せんもう)がなく、花冠は5裂し裂片は広倒卵形で雄しべは10本あり、花糸に毛がない。果実は楕円(だえん)形、長さ約1.5センチメートルの蒴果(さくか)で、10月に褐色に熟して裂ける。本州の近畿地方以西と四国、九州の山地に分布する。

　変種のアカヤシオはアケボノツツジに似ているが、花柄に腺毛が多く、雄しべ10本のうち5本は花糸の基部に微毛がある。本州の福島県以南に分布し、花の白いものをユキヤシオという。四国の西南部と九州の市房(いちふさ)山や高隈(たかくま)山などの山地には花柄に腺毛があり花糸に毛のない基準変種ツクシアケボノツツジがある。庭木として植える。

［小林義雄　2021年4月16日］

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