A post at garden rant got me thinking today. And then I went and read another article that they pointed me to. The whole subject is weeds again. Those horrid things that we would all like to get rid of…or do we?

In my weeds class, we spent an entire lecture going over the definition of a weed. There is no easy answer. My favorite is a plant in an unwanted place. It’s one you want to get rid of. But do we really want to get rid of all our weeds? The post pointed out that many weeds provide the benefits of plants in places that would otherwise be bare–like a dandelion in a sidewalk crack. That is a good thing, really. And I’ve always been a fan of things like clover in lawn. It fixates nitrogen, and can reduce the need for the tremendous amount of fertilizer we like to put on our lawns. It forms a nice, symbiotic relationship with the grass.

But I thought they were drawing the line a little too far going on to say that tamarisk is a good plant. It’s drying up our stream beds, and replacing other, better species. I know there is an endangered bird nesting in them. But there were nesting trees before tamarisk–ones that didn’t dry up the stream beds, and create a monoculture of a single plant.

Where do I draw my line? If a plant helps biodiversity, it’s good. So a dandelion in a sidewalk crack–good. The hordes of maples planted as street trees–not so good. Invasive, like purple loosestrife that take over acres of previously biodiverse wetland–horrible. We need as many plants as we can get, but they should help encourage a nice, biodiverse ecosystem. Biodiversity means everything works better, it survives better, and it looks better.

We need diverse plantings in our yards if we keep replacing wildland with them too. So try not to fill up your yard just with Kentucky bluegrass.