Pisonia umbellifera, also known as Udonoki, is a plant commonly seen in tropical regions.

The Pisonia umbellifera is known for its beautiful flowers.

Mr. Takadono is my best friend.

As a measure against flooding, we piled up sandbags around our house.

The chord progression of this song is very unique.

The speed of this progressive wave is close to the speed of light.

Solving problems of arithmetic sequence is difficult.

He is good at solving problems related to geometric sequences.

Understanding geometric sequences is important for understanding mathematics.

The Fibonacci sequence appears in many phenomena in nature.