The lushness of the garden's flowers, with their vibrant colors and sweet fragrance, was breathtaking.

lushness 是形容词 lush 的名词形式，lush 本意是"茂盛的、葱郁的"，形容植物生长得茂密而旺盛。加上名词后缀 -ness 后，表示"繁茂的状态或程度"。