Not long ago, my girlfriend gave me a cactus. Like many things with her, I decided not to ask why. She has an interesting idea of what constitutes a present. She’s given me a plastic llama and moose, books that she’d read and not particularly liked, and a carved wooden box that used to hold cigars and that, when I received it, held a paper clip and one earring. I think I speak for everyone reading this when I say – huh?

“It was my mother’s,” she said, and I wondered if some day I would have a conversation with her mother, who’d say, “Oh, and by the way – I’d like my cigar box back.” Worse, suppose we broke up. It would turn into one of those messy stories you read about in the advice columns, although usually the item is a ring, or something of value that the mother thinks is now hers again. I could imagine the advice lady saying, “While the cigar box technically belongs to the young lady, she would demonstrate considerable class and tact to return it.”

It worries me; I don’t want to keep anything in the box for fear I’ll get attached to it. On top of that, it has both the appeal of being a girlfriend-gift and the creepy factor of having belonged to her mother. I keep it in the back corner of my closet behind a shoebox, where I don’t have to look at it.

But the cactus was charming, like a green spiky ping-pong ball sitting in a little terra-cotta pot. The spikes are so small and soft that they feel like fuzz. I took it as a show of good faith that she trusted me to take care of something. I don’t know why: I’m chronically late, and I have the kind of mind that can remember how to find the volume of a cone but has trouble with things like birthdays – and plants.

“Don’t worry,” she said, when I brought this up. “It’s a cactus. It doesn’t need much. Just put it in the sun and water it whenever you remember.”

I’ve killed plants before. It’s not that I don’t have good intentions; I just forget about them. They’re small and they don’t call out, “Sarah! You need to take care of me!” They don’t swarm around your feet, nudging you toward the food dish like cats and dogs. They just sit there, in a polite “Don’t mind me; I’ll just wilt then” way.

So I am determined. This time I am not going to screw up; the cactus will have everything its green heart could want. I water it every night at the sink; sometimes in the morning, too, if it looks dehydrated.

Even so, it’s not doing so hot. It’s developing this weird crease in its center, so it looks less like a ping-pong ball and more like a prickly peanut.

And, because I’m paranoid, I’m starting to wonder whether this is a trick plant that doesn’t grow but just gets a funny crease and then keels over. This isn’t a good chain of logic to follow, because it gets me into other troublesome pits. I can see my girlfriend smiling to herself, thinking, A cactus. I gave her a sad little cactus that doesn’t even grow. And she was so grateful. Sucker.

And if the cactus wasn’t meant kindly, what about the other presents? I always assumed that they were part of her slightly off-kilter charm, like her earnest lectures. But now I can hear her snickering: “An old wooden cigar box. And I told her it was my mother’s!”

And howling over the plastic moose and llama: “She adores them! What a rube.”

I begin to imagine my next scathing e-mail: “Guess what? I just said thank you to be nice. I never liked them! ROFL.”

Wow, what razor-sharp wit, there.

And I do like them.

I especially love the cactus, my sad little cactus that I can’t seem to do much for. So I went online, and I found this: “A cactus can suffer from overwatering, and may crack … Cacti can tolerate occasional mistakes in watering. Death by slow dehydration, because people are too terrified to give their plants what they need, is not any better than death by overwatering.”

Great. I can’t water it, and I can’t not water it.

Love is a cactus.