PlantFiles: Center Stripe Agave, Thorn-crested Agave
Agave lophantha

Zone 9b coastal Otago New Zealand
Is this lophantha or iophantha?? No one seems to know!
I recently acquired two small A iophantha specimens and initially found them a little difficult to ID since they are by no means commonly available down here- these two little guys were the first ones Id come across. They were sold to me as the Shin Dagger (lechuguilla) and though I am totally in love with that name :-) my iophanthas are a bright forest green with a pronounced lemon yellow mid stripe and the outsides of the leaves are covered in little pale slashes, not the dark ones of the lechuguilla. Their rosettes also seem to be a different shape from the pics Ive looked at, the lechuguilla being more upright, the terminal spines being also thicker and differently-angled.
These are dangerously thorny little suckers so not child or pet friendly- keep them clear of paths etc.
That said, they are mightily attractive with their bold stripyness and evil thorns, and unlike some of my other agaves they seem to have settled in quickly, rooting in nicely and handling the blazing mid summer sun without sulking or withering. Even the rootless smallest offset has been perfectly happy with huge temps swings and quite a lot of rain, with no sign of rotting out.
They are eye-catching right from pup stage, which is a big plus in my book as a relatively new agave fancier with limited access to the more exotic species. (wrong hemisphere!) They are a good contrast to all the silvery blue types and their greeness makes them easy to fit into a general garden setting.
Not sure on the frost-hardiness yet, but Im picking it can withstand some, and maybe survive a good bit of hail without getting too pockmarked due to their tough fibrous structure.
Generally I have found that the more leathery and fibrous an agave's leaves are, the more frost they can take.
Your cat wont sit on it and that's always a bonus!

It handled a VERY cold winter in Maryland (2006-2007) without damage. IT was well mulched and in vey well draining soil. But, I am very impressed with it's hardiness. Wouldn't want to fall on it though....

Though this is a pretty striking Agave, it is not one of my favorite, mostly because it suckers into one of the most intensely spiny, dangerous cluster of plants you can imagine. I grew this plant at my previous location and regretted it later on- nearly impossible to remove suckers and the spines can go through your boots. But grown in a pot, it is a wonderful looking species.

Easily confused with Agave lechuguilla.
The differences are:
A. lophantha's leaves are wider in the middle.
Some A. lechuguilla have a stripe in the middle, though faint, but A. lophantha always has the brighter stripe on the average and sometimes faded.
The dried thorns are really close on both but different shape.
A. lophantha dosen't have the dark broken streaks on the outside of the leaf.