I know absolutely nothing about flowers, so any help or advice you can give will be appreciated!

We moved into a new house and we have these growing in our back yard - I thought they might be orchids, but someone at the orchid forum told me that they weren't

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and:

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You can't see it very well in the picture, but the leaves of the plant end in these little twist tendrils that hold onto things. We have these in four different spots in the yard, and would like to add more if it is possible.

I looked through several orchid/tropical indexes but couldn't find this anywhere. If anyone could give me some guesses about what it might be so that I'll know how to care for it and propagate, I'd really appreciate it!

Thanks!