For more than 10 years, a Mandevilla vine climbed the center support of my grape arbor to bloom in late summer. This year I noticed a vine among the grapevines with different buds and leaves.
I have yet to catch a blossom open. They obviously bloom at night.
Mandevilla has a different leaf, a different bud color. This vine failed to return.
My best guess is Ipomoea macrorhiza.
No clue what critter brought a seed to this spot.
Last night I was occupied with watching Night Blooming Cactus open
and forgot to go out in the darkness to look. Maybe tonight I'll remember now that I've addressed the plant.
Wrapping around the stems of grapevine, it is a vigorous climber.
If my ID is correct, Ipomoea macrorhiza is native to the southeastern states. It has a small tuber rather than the shallow roots of other morning glories. The bloom is much larger than a regular morning glory. My opinion of morning glories has always been that they are invasive field weeds.