Two hundred years ago this week, as negotiators from Maryland and Virginia parleyed in his Mount Vernon house, Gen. George Washington went about his estate transplanting trees. He recounted this activity in his diary. The temperature at noon on March 28, he noted, was 54.

Yesterday, on the 200th anniversary of the signing of the Mount Vernon Compact, several dignitaries -- including the current civilian and military heads of the Army -- joined in mid-70s weather in planting a hemlock on the edge of the bowling green that forms the mansion's front yard.

The planting was apt, Librarian of Congress Daniel Boorstin observed at a ceremony sponsored by the Army and the Mount Vernon Ladies Association, which maintains the first president's estate. For, he related, the Mount Vernon Compact, the first of its kind involving the 13 newly independent states, sowed the seed of events that led to the writing and adoption of the Constitution.

Secretary of the Army John O. Marsh Jr., a former Virginia congressman, said the Army's cosponsorship of the event was appropriate, since Washington was its first commander and the Army has been a staunch defender of the Constitution.

Others joining in the tree-planting on a gorgeous spring afternoon included Gen. John A. Wickham Jr., the Army chief of staff, and Mrs. Thomas Dunaway Anderson of Houston, the regent of the Mount Vernon Ladies Association.

The audience included a large contingent of four-star generals who, one lesser-ranking officer explained, are currently at the Pentagon for a meeting of theater and field army commanders, and who got the afternoon off -- with a hint from Marsh that they and their wives would probably enjoy spending part of it at Mount Vernon.