Mandarin Lan for "orchid" is more exactly lan2 or lán as written in Pinyin (a system to write Chinese with Latin script) because the "a" is spoken in the second tone, means the tone rises.
Strictly speaking the name does not mean "beautiful orchid" but simply "orchid". To add "beautiful" would need another syllable and give a name like Meilan (which seems to be in use as well). But of course an orchid is supposed to be beautiful.
The core meaning of this character is some kind of fence to bar entry to some place. As such it has nothing to do with flower in general or orchid in particular; it just happens to stand for a word that is also pronounced lan2.