Ajisai: Hydrangea

Hydrangea means container of water. Hydrangea (Japanese name is Ajisai)is a general term for Plantae Hydrangeae Hydrangea. Generally what is planted is Hydrangea macrophylla f. hortensia.(Seiyou Ajisai).Seiyou Ajisai is garden variety of Hydrangea macrophylla (Gaku Ajisai).

Height of tree is 1 to 2 meters. Leaf color is lucid pale green and leaf vein can b clearly seen. Leaf shape is ovoid with serration. Generally Hydrangea blooms from June to July. It is said to be an ornamental flower. Also, stamen and pistil are in devolution (Neutral flower). What seems petal is calyx. Regarding Gaku Ajisai ornamental flower blooms around crowding neutral flower. But regarding Seiyou Ajisai almost all flowers are ornamental flower.

Flower color change gradually due to anthocyanin–a blue, violet, or red flavonoid pigment found in plants–which is affected by acidity of soil, amount of aluminum ion, and the number of days from bloom. Generally it is said that if acidity of soil is high the color of flower is blue if acidity of soil is low the color of flower is red. But acidity of soil is only one factor of change color of flower out of many. While the start color is blue which changes gradually to red, there are some cases that the color of flower is green. There are garden variety what has green flower. But some of the flowers are parasitized by phytoplasma, this is an untreatable disease for now.

Hydrangea contains poison. If one eats it, one suffer from poisoning. A symptom is hyper ventilation, excitation, walk with a tottering, convulsion, paralysis. There are some cases that through these symptoms and die. It is concluded that these symptoms factor is glycoside. But recently it is concluded that causative agent is not glycoside but another agent.

Hydrangeas are popular ornamental plant, grown for their large flower heads, with Hydrangea macrophylla being by far the most widely grown with over 600 named cultivars, many selected to have only large sterile flowers in the flower heads. Some are best pruned on an annual basis when the new leaf buds begin to appear. If not pruned regularly, the bush will become very leggy, growing upwards until the weight of the stems is greater than their strength, that point the stems will sag down to the ground and possibly break. Other species only flower on ‘old wood’. Thus new wood resulting from pruning will not produce flowers until the following season.

In Japan, ama cha, meaning sweet tea, is another herbal tea made from Hydrangea serrata, whose leaves contain a substance that develops a sweet taste (phyllodulcin). For the fullest taste, fresh leaves are crumpled, steamed, and dried, yielding dark brown tea leaves. Ama-cha is mainly used for kan-butsu-e (the Buddha bathing ceremony) on April 8 every year. the day thought to be Buddha’s birthday in Japan. Ama-cha is poured over a statue of Buddha in the ceremony and served to people in attendance. A legend has it that on the day Buddha was born, nine dragon poured Amalita over him; ama-cha is substituted for Amalita in Japan.

If you want to see Hydrangea in Kochi, go to Ajisai Gaidou in Haruno town. There are ten thousand Hydrangea along the irrigation canal. The best time to see is in late may to early June.


  1. Ajisai is very beautiful.Many-colored flowers enchant me. When this flower is seen, I feel the start of summer.


  2. It was able to know the feature of the hydrangea.
    It knew the poison fang was in the hydrangea.
    I want to see 10,000 hydrangeas.


  3. Ajisai is very beautiful. So I like Ajisai since I was very young.
    Flower color change by environment of soil was very interestig topic for me.


  4. I watched Ajisai in this june. It’s a really beautiful flower. But, i wonder they have poisons. Your article is easy to understand, so i want to know them more and more!


  5. Rarely there are accidents for the poison, because the shape of leaves similer to shiso “perilla”. The beautiful flower has something method to guard itself.


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