Baring-Gould’s sources: Gallican Martyrology. Authorities:—Mention by Flodoard in his Hist. Eccl. Remensis, lib. iv. c. 9; and a life from the Lections of the Avenay Breviary; a life given in Colgan; all late.

Tresan , with his six brothers and three sisters, left Ireland, their native place, and settled at Mareuil on the river Marne, in France, where Tresan hired himself as swineherd to a nobleman. He was wont to drive the pigs to the door of a little church dedicated to St. Martin, and to stand at the door and listen to the recitation of Matins [the night prayer of the Divine Office], and assist at the holy Sacrifice of the Mass. By this means he became gradually so thoroughly acquainted with the divine office, that S. Remigius [bishop of Reims who baptized Clovis, king of the Franks], hearing of him, and having evidence of his sanctity, ordained him priest. The legend is told of him that one day having celebrated Mass in this little Church of S. Martin [St. Martin of Tours (d. 397), soldier turned bishop], where he had learnt the holy offices, he returned to Mareuil, but being weary, he thrust his staff into the ground, and laid himself down and slept. And when he woke up, behold the staff had taken root and budded. Then he left it there, and it grew to become a great tree.

When he was dying, the Holy Eucharist was brought to him. He rose from his bed, and casting himself down on the ground, exclaimed, "Hail, most blessed hope, and most holy redemption! Hail, true flesh of Christ, to me precious above gold and topaz and all most goodly stones! Hail, most blessed blood of Christ, poured forth to ransom me, a sinner, and wash away my stains! Hail, Jesus Christ, defend me against the ancient enemy, that the prince of darkness secure me not! I pray thee, number me with thine elect." Then he received the holy Viaticum, and sighed, and his soul had fled.

Relics at Pont-aux-Dames, in Brie. In Art he is represented with a budding staff.