Mondrian Flower paintings I can find. Although dismissed by many writers as only being created because the abstracts weren't selling, and even if Mondrian resented having to paint them, I have enjoyed the research and think there are some real gems. They also played a clear role in the path towards abstraction.
The impetus behind this was finding a homage by Colin McCahon, Mondrian's chrysanthemum of 1908, 1971, shown on the link.
There are around 180 flower drawings and paintings overall: a more detailed analysis of the mediums used, subjects and whereabouts will follow.
I came within a reasonable distance of owning a Mondrian soon after developing my interest in the early 2000s: a flower watercolour popped up on eBay with what looked like a reasonable provenance, starting at $200 but only shipping to the USA. I would have been prepared to travel over to pick it up but the sale was withdrawn long before the end.
There is an interesting homage here.
The two images shown are: