Final answer:
The tertiary line in Ikebana arrangements represents the third and final line, often symbolizing the heavens or the spiritual realm. It adds a sense of verticality and connection to the divine.
Step-by-step explanation:
The tertiary line in Ikebana arrangements represents the third and final line. It is usually the tallest and most dominant line in the arrangement, and it creates balance and harmony with the other lines. The tertiary line often represents the heavens or the spiritual realm and adds a sense of verticality and connection to the divine. For example, in a traditional Ikebana arrangement, the tertiary line might be represented by a tall branch or flower that reaches upward, symbolizing the transcendence of the physical world.