A guess. I am pretty sure it is Crassulaceae. The family has very few members with tubular flowers. There is a description in the web site Plantzafrica. Click on Plants of SA, then on C and scroll down.
It's the African Daisy I am worried about. There is so much of it and it is spreading. Isaacs does not just have South African plants. Look at the big patch of Agave americana.