Asteraceae members- Nairobi, Kenya

Cultivated, potted, garden plant with Blue Flowers seen in Nairobi on 3rd Jul,16.
Would like to know the correct id.

Asteraceae For ID : Kenya : 25AUG16 : AK-28 : 28/28 : 1 post by 1 author. Attachments (1)
Asteraceae seen growing wild on the 9th of July.
I have only one picture.

Just a guess....
Could be Melanthera Species?