I am a type of flower and I was used in a story with emerald buildings what am I

I'm not an island, but I'm encircled by an oasis. To enter, you must be on a need to know basis. If I deem you worthy, I drop my wooden tongue, To protect you from the crocodiles among.

Though ages old, I've lost my sting From war call to toddler's toy. Whether steel or slit or snare, Can you hear me? I'm always there

Throughout Egyptian history, this insect's likeness has often been used to make amulets. It shares its name with a German car. It makes up about fourty percent of all known insects.

I’m great in China, I’m divisive in Germany, And I’ll make America great again?