If you are hunting sharptail in SD you will encounter cactus, primarily prickly pear, but also that little obnoxious sucker that I call "mini-cholla". It has a hook on the spine so it is actually hard to remove. I'm seeing prickly pear growing everywhere on the grasslands. With all the moisture this year, the stuff that was little last year is much larger, which is good - the dogs can see it, but there are patches of new cactus that is hidden in the grass. I try to avoid boots as they cause my dogs to fatigue early, especially when it is hot, but I carry boots 100% of the time, "just in case".
There are also places up here with massive infestations of goat heads and/or sand burrs in old cultivated fields that have been left fallow. Often these are good for pheasant, I assume because most people either don't have boots for their dogs or their dogs won't wear boots.