Her announcement saw the simple flower, supposed to represent the poppies in Flanders fields from the First World War, firmly entangled in the briar of Northern Ireland politics.
Mrs McAleese, who was elected as Ireland's head of state last week to succeed Mary Robinson will be attending a Remembrance Day service on Sunday in Dublin. But she said she had decided "after long deliberation, apart from the shamrock, the president should not wear emblems or symbols of any kind". That included the poppy.
Her decision outraged many Tory MPs, and Ulster Unionists. Andrew Mackay, the Tory spokesman on Northern Ireland, said "It's obscene for Mary McAleese to confuse the poppy with any sectarian issues. It's a mark of respect for the millions of people who gave their lives in both world wars, including many thousands of Irish men and women."
David Trimble, the Ulster Unionist leader, said: "If she had wanted to make a significant contribution, that was her opportunity. It is a missed opportunity."
Mrs McAleese, 46, who was born in Belfast, and has been deeply committed to the peace campaign in the North, was responding to requests to wear the poppy from the Royal British Legion and other groups.
She was advised against it by Irish ministers, including the Irish Defence Minister, Michael Smith, who said it was private matter for Mrs McAleese but he believed that she could be creating problems for the future if she wore an emblem.
By announcing her decision, however, she stepped into a row over the wearing of the poppy north of the Border, where 20 workers at the Coats Viyella textile factory in Londonderry have been suspended for wearing the poppy against a company ruling.
Mo Mowlam, the Northern Ireland Secretary, had been trying to calm tempers about the poppy and Mrs McAleese's dilemma. She said that she hoped the poppy was not going to become a "political football".
The row over the flower has reopened old wounds in Northern Ireland. Remembrance Day may be seen by some as a militaristic, support for the British Army, regarded by some nationalists as an occupying army. Others remember that many from the Irish Free State volunteered for the British Army, in spite of Ireland's neutrality, in the Second World War.
More recent events cast an even darker shadow - notably the 1987 IRA bomb atrocity at Enniskillen in which 11 people lost their lives.
Lembit Opik, the Liberal Democrat spokesman on Ulster, said: "The concern about poppies is a symptom, not a cause of the differences in Northern Ireland. When such events cease to be an issue, we will know we have made progress."