St. Luke

Green: The colour of nature symbolizes life and growth. We all desire, and rightly so that our bodies should grow strong and healthy. But how many of us are equally anxious to grow spiritually and mentally? Very few; and yet this growth is so much more important than mere physical growth. We should ever be alert and seize every opportunity which will lead to greater knowledge, a broader outlook on life, and above all, a deeper love of God and of truth.
Luke

St Luke begins his gospel by mentioning the priesthood of Zacharias and because the ox was the usual victim of a sacrifice offered by a priest in the Old Testament, he is often represented by an ox.