タマアジサイは、谷川沿いの木陰などで群生。枝先で玉のような蕾が丸く膨らみ、夏から秋にかけて控えめながら煌びやかな花を咲かせます。
Tama Ajisai grows in clusters in the shade of trees along river valleys. It has ball-like buds that swell at the tips of its branches, and blooms in modest but brilliant flowers from summer to autumn.
【仮名】タマアジサイ
【和名】玉紫陽花
【英名】Tama Ajisai
【学名】Hydrangea involucrata
【誕生】08/ 02
【開花】07, 08, 09月
【花色】White, Purple, Violet
タマアジサイ
タマアジサイの概要
タマアジサイはアジサイ科アジサイ属の落葉低木。日本では本州の東北～中部地方、四国、九州、伊豆諸島、トカラ列島に分布しています。「沢紫陽花」とも呼ばれ、谷川沿いの木陰などで群生。玉のような蕾が丸く膨らみ、夏から秋にかけて控えめながら煌びやかな花を咲かせます。
タマアジサイの名前
タマアジサイの名前で「玉」の由来は蕾が丸く膨らむから、紫陽花の語源は「小さな藍色の集まり」。自生地が東アジアに限られるので英名はありません。ラテン語の属名ハイドランジアは花が雨期に咲くから「水の器」、種小名インボルクラータは蕾の造りから「総包」という意味。
タマアジサイの枝と葉
タマアジサイは枝と葉に短毛が密生。枝は叢生し、樹齢を重ねると灰褐色の樹皮が薄く剥がれ落ちます。葉は対生し、先の尖った長楕円形で縁がギザギザ、表裏がザラザラ。この葉は昔、煙草の代わりに用いられ、「山煙草」とも呼ばれました。枝先で総苞に包まれた球形の蕾が肥大。
タマアジサイの花と実
タマアジサイは蕾が綻びると２種類の花が咲きます。真ん中の両性花は赤紫色～青紫色で小さく、花弁が５枚、雄しべが10本、雌しべの先が２裂。花後は丸い蒴果を結び、鬼の角のような花柱が落ちずに残ります。周りの装飾花は白色で大きく、花弁が３～５枚。横を向いて開きます。
Tama Ajisai
Introduction of Tama Ajisai
Tama Ajisai is a deciduous shrub of the family Hydrangeaceae. In Japan, it is distributed in the Tohoku to Chubu regions of Honshu, Shikoku, Kyushu, the Izu Islands, and the Tokara Islands. Also known as “Hydrangea of the stream” in Japanese, it grows in clusters in the shade of trees along valley rivers. It has ball-like buds that swell out in a round shape, and blooms in modest yet brilliant flowers from summer to autumn.
Name of Tama Ajisai
The Japanese name of Tama Ajisai means “ball-like Hydrangea” because the buds are round and swollen. It does not have an English name because its native area is limited to East Asia. The Latin genus name Hydrangea means “water vessel” because the flowers bloom during the rainy season, and the species name involucrata means “involucre” because of the structure of the buds.
Branch and leaf of Tama Ajisai
Tama Ajisai has short hairs on its branches and leaves. The branches grow in clusters, and as the tree ages, the gray-brown bark thinly peels off. The leaves are opposite, oblong with a pointed tip, and have jagged edges, and the top and bottom of the leaves are rough. This leaf was used in place of leaf tobacco in the old days, and was also called “mountain tobacco”. At the tips of the branches, spherical buds wrapped in involucres enlarge.
Flower and fruit of Tama Ajisai
Tama Ajisai produces two types of flowers when the buds open. The bisexual flowers in the middle are small, reddish-purple to bluish-purple, and have 5 petals, 10 stamens, and the tip of the pistil is two-lobed. After flowering, it forms a round capsule, and a stalk like a demon’s horn remains without falling off. The surrounding decorative flowers are large, white, and have 3 to 5 petals. Open it sideways.
