Vivagirl5

I totally agreed with cgoodwin and RobinB. These plants are the "Feverfew". They are not "Kalimeris, pinnatifida Hortensis" because if you look at the leaves of this plant you may noticed that it is has daisy-like leaves:

http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=P820

As for "Feverfew", it has a scented-Gerinum-shaped leaves like so:

http://www.smppa.org.uk/Natural_History/Plants/Large/Wild/Feverfew.jpg

If you noticed that as you touch the leaves and it has a strong smelly-nausea smell that is a "Feverfew." I have these in my garden and it is an invase plant that spread quickly throughout into the next year. My word to you is please look closly at the leaves and check if it smells or not.

Just like 2sad and Comarish59 said. It is indeed " Catclaw vine, devil's claw, Unicorn Plant or Ram's horn". All the names says the same plant.

If you go to:

http://davesgarden.com/guides/pf/go/333/

and read all the comments, LOL, you would find that it is indeed what you are wondering about. They are a natived to the Southwest of the USA and tolerate very well to the heat and drought. Maybe that is why they grow so well and are doing so fine. Good Luck!

yeap, you are right! It is Meehan's Mint/Creeping Mint.

Here is the definition:

Creeping mint

A common name Meehania cordata, a fairly hardy, low-growing perennial. It grows to a few inches, spreads by stolons, and has heart-shaped, wrinkled, opposite leaves and spikes of hairy lavender or lilac flowers. Used as a ground cover in shade. Also known as Meehan's mint.

http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?code=A786

I hope this answer what you were thinking. I agreed that at first you would think that this is not it because you said that the leaves were square shapes, but if you look closely the leaves are actually heart shape. The only conclusion I found is that this is really Creeping Mint aka Meehan's mint.

The plant is identified as J. procumbens, commonly known as Waterwillow. It is a different kind of Shrimp Plant.

You can read more here:

http://www.hear.org/pier/species/justicia_procumbens.htm

The picture of the plant is very similar to the one you have:

http://www.hear.org/pier/imagepages/singles/Justicia_procumbens_var_simplex_AP_W_IMG_8143.htm

I hope this helps. I think the reason why it is not blooming is because it need to be in a much warmer place to bloom since it is from Central America and Southern part of Asia.