Ajisai is divided into two types. They are "Gaku-ajisai[ガクアジサイ](Hydrangea macrophylla)" and "Hon-ajisai[ホンアジサイ]" or simply called "Ajisai".
Hon-ajisai is a common Ajisai which has hemispherical flowers. It is the most popular Ajisai. Actually, the hemispherical part of Hon-Ajisai is not flowers but the developed calyx. There are real flowers in the center of each calyx. Many kinds of Hon-Ajisai were created in the world and have spread over the world.
The origin of Hon-ajisai is unclear. One theory says that Hon-ajisai was made from Gaku-ajisai. But another theory says that Gaku-ajisai is a wild species lives in Japan.
Gaku-ajisai is native to Japan. Gaku-ajisai does not have hemispherical calyx like Hon-ajisai. It has small flowers around flowery calyx. Its popularity has grown in recent years because of its unique figure.
In general, the colors of Ajisai change by each soil. It becomes blue in the acidic soil and red in the alkaline soil. Ajisai is beautiful but a poisonous plant.
There are Ajisai spots all over Japan. Around Tokyo, Kamakura[鎌倉（かまくら）] City(Kanagawa Prefecutre) has many Ajisai spots Especially, Meigetsu-in[明月院（めいげついん）] is famous as a temple of Ajisai.