Not an alien. An indigenous tree wisteria in flower.
There are tree wisterias elsewhere in the park, but I've never been lucky enough to see one in flower. Wow, it looks stunning - thanks for posting the pix, avon vosloo.
website has an entry on the tree wisteria, Bolusanthus speciosus
, which also includes photos.
The tree wisteria is certainly one of the most spectacular of our indigenous trees when in flower, mimicking the splendour of the jacaranda, which unfortunately is proving to be an invader species in parts of South Africa. Given time and effort this tree could replace the jacaranda trees from Argentina and carpet Pretoria streets with indigenous purple blooms instead.
This decorative, small to medium-sized tree is deciduous, dropping its leaves only for a short period in early spring. The tree is normally multi-stemmed, but it can be pruned to form a single stem. The bark of the stem is brownish grey, rough and deeply fissured. Leaves, which are spirally arranged, are suspended from drooping branches.
The drooping, blue-mauve, fragrant, pea-like flowers hang from the branches in bunches, often covering the whole tree. Flowering time is from August to January (spring and early summer). Flowers are followed by papery, brown fruit pods, that hang from the branches in clusters, and never split to release their seeds. Being a protected tree in South Africa, wild specimens may not be removed, cut down or damaged.