The morning glories shown here came from a packet of seed purchased long ago under the name 'Grandpa Ott'. There are at least two other very similar types making the rounds: 'Star of Yelta' and 'Kniola's Black'. On-line you can see the lively discussion carried on by morning glory enthusiasts about which is which. Am I using the correct name for my plants?
Whatever they are at the varietal level, at the species level these are Ipomoea purpurea. In other words, these are the morning glories which will drop seeds and reappear year after year. The ones you see in the photo have been doing that for at least a decade here. Like dahlias, these morning glories get better and better through the summer; they are at their best just before the frosts finish them off for the year.