Mmmmmm... bird seed.”— Pecker
The Life Seed is a seed from the Great Tree, appearing only in Jak II. It was harvested and protected by Samos Hagai, who used it to harness green eco sage capabilities. Samos hid the seed in his hut before his departure from Sandover Village, and was later recovered far into the future at the sacred site, which was Samos' hut in ruins. Metal heads are known to be particularly attracted to the Life Seed's power.
After Jak recovered it from the abandoned hut, he took it to Onin in order for her to prepare it for the Shadow. The Shadow used it to speak to the plants at Haven Forest and gain the powers necessary to become a sage of green eco.