Tithonia diversifolia
Family: Asteraceae / Compositae
Sunflower tree, tree marigold
I love this plant, fast growing, easy to propagate & beautiful flowers. But, like my angel trumpet tree, can't go long without water before wilting. Never thought about using flowers as cut flowers in a vase, but they do great as long as you recut ends every other day & putting in clean water.
Like the trumpet tree, just cut stalks, stick & dirt, keep watered & they grow. The last time I pruned this monster (now 10 ft. tall) I had 5 1gal. pots full of stalks to give away. It looks like a stick bush after you prune it, but gets leafy again in under 2 weeks.