Looks like equisetum. Do they get taller than that...?

I agree......equisetum/horsetails.

Sorry about that. No connection with the tree or its removal.

Tough to get rid of the stuff but it is possible.

Suggest you contact our county's Extension Service office. Locate that office with this interactive map:

http://npic.orst.edu/pest/countyext.htm

That is equisetum, aka horse tail, and is a plant common in poorer and wet soils. Around me, with a high water table, they grow in what at first appears to be dry sand until you dig down and find water. However, like many plants they have adapted to grow I n many soil types.

I have found that after the soil where these plants grow is well amended with organic matter and the water table drops they stop growing.

kimmq is kimmsr

"I have found that after the soil where these plants grow is well amended
with organic matter and the water table drops they stop growing."

Oh, if were it that easy!! IME. amending with OM just makes them grow better (as it does with most plants). And the water table has very little bearing........if they can grow in terraced raised beds on a steep hillside - the water table is well below the 3-4' depth of the beds - then they can obviously tolerate very well drained soils.

This is a plant that has been on this planet since the dinosaurs roamed so they are well-adapted to a very wide range of growing conditions. They are difficult to control but persistence will eventually force them out or keep them at manageable levels. I have never been able to expunge them completely from a garden where they are present but I have been able to significantly reduce their presence by removing any topgrowth I see as soon as I see it. The inability to photosynthesize weakens them.

Thank you all for your help. Looks like it'll be a task to get rid of them, but it helps to know what I'm dealing with!