It was Valentine's Day 1995. I came home from work, and in the vestibule of the Victorian house where I rented an attic apartment, I discovered a box from the florist.

My heart pounded. I'd been dating a guy for a month or so. He hadn't bought me roses, had he?

I raced upstairs, cut open the box, and discovered a tiny, blossoming shamrock plant. It was the perfect gesture: not too showy, a little bit unexpected, and a direct line into my history and into my heart.

My parents were Irish immigrants who brought to America a love of nature and gardening. They focused most of their attention on the outdoors, but my mother's kitchen was home to one spectacular shamrock plant. It lived in a large terra cotta pot atop a wrought-iron plant stand. She tended it carefully, and its success gave her as much pride as her lilting accent and her cups of strong, hot tea.

Shamrock plants, scientifically known as oxalis, come in green, deep purple, or striped varieties. Oxalis is a highly responsive plant, bending gently toward the sun, opening its leaves every morning and folding them up again at night. It lets you know immediately if it isn't well. The delicate stems droop, the roots grow gnarly and pop above the soil, and it stops flowering.

When my mom's shamrock showed any of these signs of weakness, her reaction was swift and decisive: She would shear the entire plant. I'd wake up one morning and the pot would look empty, with only the tiniest tops of the stems poking out of the dirt.

"Mom, why did you do that? It looked fine," I'd say.

"No, it didn't. It was all leggy and wispy. You'll see . . . it will come back better than ever," she'd say.

For days, I'd peek nervously at the flowerpot, seeing nothing but those stubby stems. Then one day, there would be new shoots coiling tightly against the dirt. Before long, the shoots would multiply and begin bursting upward, filling out the flowerpot more densely than before. The stems would grow in thick and lush, and the leaves would unfold every day in a thicket of purest green. Every time she cut it down, it came back with more flowers than it had ever had before.

"You see?" she'd say. "I told you it would come back."

I've never once tried my mom's slash-and-burn tactics. When my shamrock fades, I pluck a stem here and there. I spin it gently in my windowsill, waiting for the sun to revive it. My mother ravaged things, believing she would make them better. I fear that if I damage something beautiful, it won't survive.

My romance with the man who gave me the shamrock lasted about a year. The shamrock has now lasted for 20. It flourished in my sunny studio and thrived in the first apartment I shared with my husband, where I neglected it in favor of marriage and new motherhood. It survived our move to the suburbs, where its pot has been shattered and where it shares its windowsill with children's crafts.

According to the experts, neither my mother's style nor mine is correct. Oxalis naturally goes through a tough season, and the best course of action is to encourage its dormant time. I'm supposed to take my beloved shamrock into a dark room and leave it alone for two to three months, after which I can bring it back, repot it, and wait for it to magically revive.

I can't do that.

In 20 years, everything has changed. The young woman who bounded up the stairs to her funky apartment is now a middle-aged mom in a suburban ranch house. The mother who dispensed her tough-love gardening advice in a kitchen redolent of cookies and tea has passed away.

But our shamrocks are doing just fine. My sister took my mother's plant, and it continues to thrive. They flower, they change with the seasons, and they are forever anchored by roots that travel from Philadelphia to upstate New York, across the sea to County Cork and back.