Many
Ipomoea species have extrafloral nectaries but these can be difficult to see in nature.
Here is a young leaf of
Ipomoea nervosa (formerly
Argyreia nervosa) growing indoors showing a drop of nectar at the base of the abaxial side of the leaf, which will face downward when the leaf opens. The other side of the leaf, facing upwards is called the adaxial side and right now that part of the leaf is the inside of the still-folded leaf and cannot be seen.
The nectar is very sugary and attracts insects like ants and wasps outdoors.
