I thought my pic was Lamiaceae, I thought I saw square stems.
The leaves reminded me of Lamium ..deadnettle.... but my search got no where.
I have just had a reply from Ben Caledonia from New Caledonia .This is his pic...
https://www.flickr.com/photos/...
It shows Tetradenia riparia .
Quote wiki...."Tetradenia is a genus of plants in the Lamiaceae family, first described in 1830. It is native to Africa, including Madagascar"
His image of Tetradenia riparia flowers look a good match and some leaves on www look a match.....
Apparently "The natural habitat of Tetradenia riparia is along riverbanks, forest margins, dry wooded valleys and hillsides in areas where there is little frost. The natural distribution ranges from KwaZulu-Natal, Northern Province, Mpumalanga in South Africa, to Swaziland, Namibia, Angola and northwards through tropical east Africa into Ethiopia."
The plant in my pic was found in Palheiro gardens in Madeira...on the edge of the garden ..I assumed it was a weed.
Madeira's Palheiro Gardens is an amazing garden .....It grows plants from all over the world...from Africa, New Zealand, Australia, The tropics, India, China, Chile, South America and North America. " With six different climate zones, the island offers a unique environment for plants from around the world to grow and flourish.The gardens also have some of the rarest and most valuable exotic plants in the world." It is fairly high up on the mountain and temps can be very hot to rather chilly with dense fog.
So it is perfectly possible that this is a special plant not just a common weed.
https://www.exotic-plants.de/s...
.