verb

(of a living organism) grow or develop in a healthy or vigorous way, especially as the result of a particularly congenial environment.

wild plants flourish on the banks of the lake

grow,thrive,prosper,grow/do well,develop,burgeon,increase,multiply,proliferate,spring up,shoot up,bloom,blossom,bear fruit,burst forth,run riot,put on a spurt,boom,mushroom

noun

a bold or extravagant gesture or action, made especially to attract attention.

with a flourish, she ushered them inside