What style does ball calligraphy without vertex belong to?

Spherical calligraphy belongs to the flower-and-bird style.

Flower-and-bird characters (flower characters) are also called street stall paintings, colorful dragon and phoenix calligraphy, blackboard calligraphy, craftsman characters, dragon and phoenix characters, painting characters, painting characters and colorful artistic calligraphy. It is named because the strokes are mostly represented by flower-and-bird patterns. Based on characters, it uses patterns such as flowers, birds, grass, fish, insects, mountains, water and spirals to replace the strokes of characters. According to the basic glyph composition, it integrates painting and calligraphy. Color painting is richer than single ink painting and is deeply loved by children.

Folk flower-and-bird characters, also known as ink-and-wash characters, dragon-and-phoenix characters, multicolored flower-and-bird-insect-fish combination calligraphy, Tibetan calligraphy and painting, China riddle, Feisi blackboard writing and craftsman's writing, are often used to write someone's name, so they are also called famous paintings, and so on. It uses a special color brush, which can quickly draw simple objects, spirals and other strokes instead of words, and uses the structural form of hidden painting in words to skillfully integrate words and paintings to express auspicious and festive effects, and at the same time enhance the interest and visual appeal of words.

There are both the neatness of Chinese painting and the bright colors of western painting. Flying dragons, dancing phoenixes, flowers and plants, birds, butterflies and fish set each other off and make people never tire of seeing them. There is a saying that "it is difficult for calligraphers to write, but it is difficult for painters to polish", which is a wonderful flower in China's historical and cultural gardens.