Crossvine.

artvandelay, I have a tangerine crossvine growing on a vertical structure. Want to try something else.

Indu, how about 'Blue Boy' Thunbergia battiscombei? It's one of my favorites on a pyramid. It's a very 'tame' vine, and comes back even after a hard freeze.
Jim

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Try to use something that doesn't twine a lot and then freeze because it's a mess to get all the tendrils off the pyramid. Been there -- done that :-(

Jim, Thats beautiful, is that from your garden? I looked up about this vine and I liked it a lot. read that it grows to about 6 ft, so maybe pefect for an obelisk. I think it also falls into the category of a clinging vine rather than a twining vine as Roselee suggested.

Here is a link that might be useful: Blue Boy

Yeah Indu, it's in my garden. So far this year it's about 2 feet high and blooming already. Actually, I would call it's growth habit more rambling or leaning than vining. If you decide to go with this vine, I have some cuttings on the mist table, and will save you one when they are rooted.

Another vine to consider, is the Mexican Flame vine. It would fill a pyramid quickly and is really pretty when in full bloom.
Jim

Jim, can this vine take full sun???

Carrie, mine is in pretty much full sun. It's on the south side of an east/west fence.
Jim

Yes Jim, I would love to grow the Blue boy, will take one from you.

Wow! Thank you for the inspiration Jim. I have a wooden "tower" and a Blue Boy (I know him as Blue Glory vine) just starting to awaken from winter in a pot.

I believe I know just where he will spend the spring and summer

I had it in one of those weird NW spots were it was in shade most of the day and then it was blasted with full afternoon sun in the summer but it saw no sun for many months. It was very happy. I was very happy till it started infiltrating my siding. My husband made me tear it down.

Jim, is that the same vine as King's Mantle that you brought to the San Antonio swap, or a relative?

Roselee, it's a relative. King's Mantle is Thunbergia erecta. The blooms are nearly identical.
Jim