Meliai

The seven Meliai, also called "blood-born" or "silver-wives" are the first dryads to be born. They are the children of Ouranos and Gaea. Their trees are ash trees.

History
When Gaea killed Ouranos with the help of the Titans, his blood dripped onto the earth. As a result of that contact, the Meliai were born. (Thus, they got the title "blood-born".) Later, in the Silver Age, they married the men of that age. (Thus, they got the title "silver-wives".) Eventually, they passed on and reincarnated into seven seeds.

Phillip McCaffrey, father of Meg, managed to obtain the seeds of their reincarnated lives. He intended to plant them and bring them back. However, his plans were foiled by Caligula, who destroyed the McCaffreys' home, Aeithales. Hercules, a saguaro cactus, survived the destruction of that home and hid the seeds away for safe-keeping.

The Burning Maze
Meg had a dream in which she came to know where Hercules the cactus hid the seven seeds. She planted them at the ruins of Aeithales. In spite of the hostile environment, the seeds grew into saplings at an unusually fast rate. In two days, the Meliai returned to their prime adult form. They then heard the nature song of Meg and Grover Underwood in the Burning Maze.

Teaming up with Piper, the Meliai attacked the main entrance of the maze. They forced their way through to the place where Grover, Meg, Apollo and Herophile were trapped. Piper killed Medea. Then, they all teamed up and managed to force their way to the nearest exit. Outside the exit, the Meliai killed the powerful Incitatus and all of his pandai guards.

Finally, the Meliai transplanted themselves and put their roots around the pool at the ruins of Aeithales. Their magic worked so well that Aeithales rebuilt itself in a day.