What is the slowest growind flowering plant not flowering until almost 150 years old?

The slowest growing flowering plant is the Welwitschia mirabilis, a unique species native to the Namib Desert in Namibia and Angola. This remarkable plant can live for over a thousand years, but it often takes around 150 years to produce its first flowers. Welwitschia has only two leaves that grow continuously throughout its life, and its slow growth and long lifespan make it a fascinating example of desert adaptation.