Perhaps the most extreme example of this is the Agave havardiana, or Century plant. These things are all over the park, as well as (for some reason) being very popular items for decorative planters in local towns. They're pretty large and hard to miss, and they might lull you into thinking that they're easy to avoid.
That may be the case sometimes, but make one wrong move and stumble into one and you'll find out why we were mistakenly calling them "horse cripplers" for much of the trip:
Those leaves are not only stiff as a board, they're tipped with spines hard and sharp enough to go completely through a field notebook. (We tested it.) No one had serious injuries off of those, but there were some close calls. On the upside, these plants are sometimes used to make mescal and tequila, of which you might need copious quantities if you have a run-in with one of the spines.
The next offender in the plant lineup is Agave lechuguilla (on the left in this photo), which were named the collective bane of the course's existence. Also called "Spanish Saber", these nasty little knee-high bundles of misery supposedly grow only in the Chihuahuan Desert, and mainly on limestone, which (suprise!) Big Bend has a lot of.
The fun thing about these is that no matter where you are in relation to the sun, slope, water, rock type, or any other kind of environmental factor, there is always at least one of these things pointing directly at you. If you run into a patch of them, you're toast no matter what direction you're coming from. (This did happen, and we spent half an hour pulling the poor girl out of the plant and patching up the twenty or so holes it put into her legs through her pants.)
Next to that offender is one of the only plants out there that doesn't want to kill you:
Those are some of the things that aren't cacti. There's actually quite a wide variety of cacti in the park, although no barrel or saguaro like most western movies like to show (those are Arizona natives). When we visited, it rained a lot, so everything started flowering, and it put on quite a show:
(For anyone who's interested, the writing reads "PAMS, Dr. J. R. Sollidan: This is where he belongs." We came up with a theory about the pot containing the ashes of a very dedicated geologist who never wanted to leave the park, but we hope that wasn't actually the case, since the cactus was dead and accompanied by a really tacky smiling sun decoration. Any guesses out there as to who this might be?)