Getting this IDed for a friend. He writes "It is the only example I have ever seen and is on the roadside of Moana Road, Plimmerton. Pretty sure it is a wild brassica of some sort (turnip/radish) of which there are many in the area both yellow and white (?very pale blue) flowers but nothing with this colour - rather striking! Possible mutant? like the rest of us in Moana Road!!!! One photo shows the leaves"
I took a stab and suggested Hesperis matronalis. Sweet rocket.
but apparently the foliage is quite different
No idea what species. Naturalizing in flowerbed.
Large planted trees with variegated leaves and ripe fruit, and wild seedlings with non-variegated leaves
See comments on this obs of the same thing https://inaturalist.nz/observations/70803160
Occasional on edge of exotic bush beside shore-side path
As is often the case, associated with boxthorn. Sole exemplar of the morning.
Terricolous on rocky slope