Here's a breakdown of their geographical origins:

* Asia: Primarily found in Japan, China, Vietnam, and the Philippines.

* Africa: Found in eastern and southern Africa, particularly in countries like Madagascar.

* Oceania: Found in islands like Tahiti and Fiji.

It's important to note that while gardenias are native to these warm regions, they can also be grown in other areas with suitable climates, including:

* Southern United States: Gardenias thrive in states like Florida, Texas, and California.

* Mediterranean regions: Countries like Italy, Spain, and Greece have suitable conditions for gardenias.

* Other temperate regions: Gardenias can be cultivated in greenhouses and gardens in areas with milder climates, provided they are protected from frost.