The chief White House florist, Nancy Clarke, who has bedecked the Executive Mansion with roses, tulips, sweet peas and other blossoms since the Carter administration, is retiring at the end of May.

Mrs. Clarke, who has worked for six presidents, started as a volunteer in 1978 and joined the White House full time in 1981. She presides over a staff of three people and is responsible for decorating the West Wing, the East Wing and the first family’s private residence.