If trees could talk, the old Amur cork tree at Harvard's Arnold Arboretum might have made it through another New England winter.

But instead, adoring visitors have smothered the 121-year-old tree to death with love. None of the admirers who frequented the park and climbed onto its inviting limbs knew that they were contributing to its eventual demise.

The tree was ailing, partially because of the years of human weight piled upon its branches. In addition to the normal troubles of old age, this phellodendron amurense suffered from the past summer's 40-day drought.

So when 22 sixth grade girls from Boston's Winsor School clambered onto the tree's low branches for their annual Arboretum photograph on Thursday, a huge horizontal limb cracked and the trunk split to the ground.

The students escaped injury, quickly climbing down from the tree.

The phellodendron amurense did not fare as well. Arboretum workers removed three quarters of the tree on Friday because they felt it posed a hazard to visitors.

They left the cracked trunk and one long, low branch which sweeps the ground to an expanse of about 20 feet.

The tree's grandeur has been reduced to the form of a bench that will remain indefinitely, according to Assistant Director for Living Collections Peter Del Tredici.

"Everybody's heart broke.... Who wants to be on the cork tree when it cracks?" said Karen Funkenstei science teacher at Winsor who was with the students on their annual field trip to the Arboretum.

Del Tedici was more philosophical about the loss.

"It died as it lived.... Eventually, biology is going to assert itself over emotionality," he said.

In the past, Arboretum officials had difficulty keeping visitors off the tree, which graces Meadow Road, Del Tredici said.

Approximately 200,000 people visited the park each year, attaching themselves to the tree's branches and suffocating its roots.

Arboretum pruners had also been removing dead branches from the tree over the past 10 years, increasing its frailty, he said.

The tree had come to be personified as a gentle, inviting grandparent figure in the park.

"It was the sweetest tree," Funkenstein said.

And just as grandparents are symbols of a vivid past, the old cork tree has its own remarkable history.

Just two years after the Arboretum was founded in 1872, this amurense arrived in Boston as a seed from the Imperial Botanic Garden in St. Petersburg, Russia.

In fact, the name amurense is derived from the fact that it originates in the Amur River valley in Manchuria, host to harsh winters.

Dubbed 143-A in its new home, indicating that it was the 143rd tree to join the arboretum, the cork tree was probably one of the very first trees planted on the grounds of the park.

By yesterday, two weeks after its 121st birthday, the tree had become an Arboretum legend.

Even cut down it may continue in this role, as part of Harvard's annual capital campaign. A potential plan is to create discs from the saved wood of the removed portions of the tree, which might be presented to financial donors to the Arboretum as an expression of gratitude, Del Tredici said.

The tree's collapse may also provide an opportunity to educate park visitors about the effects of human ignorance on the environment.

Del Tredici notes, however, that most of the people who come to the Arboretum ignore the anti-climbing warnings.

"People just don't think," he said