There are a couple of little known trees but the most common flower is Xylobium a family of Orchids.
xeranthemum
Xtabentun is a Mexican liqueur. The ingredients include the nectar from the xtabentun flower.
there is no flower
X-rayXenonXeroxSince the question asked for "three-letter" words beginning with "X", how about "xis"?
orchid oleander
Peony
A four letter word beginning with C and ending with X is crux.
There is no synonym for awesome beginning with the letter x.
Xylophone, xray,
Sage is one tye of flower.
A rose is a type of flower that begins with the letter "r".
Xeranthemum and Xylobium are flowers. They begin with the letter x.