Coral cays are colonised by many flowering plants. The largest and most conspicuous member of this group in the Indo-Pacific region is the tree Pisonia grandis. The mangroves may also be common in sheltered sites. The only group of this whole kingdom to successfully colonise underwater is the seagrasses. These are members of the monocotyledons of the Angiospermae (see seagrasses). Seagrasses are common on coral reefs.

• To have a vascular system for transporting nutrients.
• To have supportive cells around the reproductive (gamete) cells.