For my Parents (Plant Style)

This post is more directed for my parents, but you all are of course welcome to see what I have to share.
We have these spiky plants back home in NC in our yard.  They're painful if pricked by their leaves, and we are forever trying to remove them from the yard.  However, no matter how often we pull and dig them out, by next summer they return.  I've only ever seen them as tall as my waist, but I've discovered that they're here in Moyo Hill as well! And they're bigger, sharper, and ultimately badder than those we have in our back yard.  A photo has been provided with myself standing by to give you a rough idea of how large these puppies are (just as a note, I'm 5'6" without my boots on).
They are the Siso plant, and in Kiswahili they are called kitana.
It makes for marching about the countryside a bit difficult when faced with a wall of these, so we try our best to dig through all of the other foliage and flora, and to avoid these sharp buggers.  My t-shirts and cargo shorts are no match for the mighty points of the kitana plant!