Guava

The history of guava in Taiwan is fairly simple, it was introduced from China in 1694. Its Chinese name is 番石榴 (savage pomegranate). Taiwanese called it 林菝仔(Na-bu-la). Southern Taiwanese dialect puts it as Bala (might have been Portuguese as pointed out by Katy Biggs), and further reverse-translated into Chinese, 芭樂 (Ba-le).

Pearl guava

Presumably, there are 150 different varieties of guava. We know of only 2, Pearl Guava (above) and Red-cored Pearl Guava (or Watermelon Guava) (below). 【Note: The Milk Guava is simply from Pearl Guava trees watered with expired and slightly fermented cow's milk.】

Watermelon guava

Guava is grown in Southern Taiwan in about 6,000 hectares of groves and available year round. Leading in production is 燕巢鄉Swallow's Nest Village in Kaohsiung. Wild ones can be found everywhere in Taiwan, with the fruit the size of a Tankan, still quite edible.

Source: knifeedgeforums.com

Interestingly, the seed-embedded core of guava refuses to be processed in children's small intestines, so the fruit was generally avoided by knowledgeable kids (expert opinions to the contrary notwithstanding). A good alternative use of guava is to turn the perfectly Y-shaped hard-as-steel guava branches into slingshots. Rubber strips cut from the inner tube of a bicycle tire works better than rubber bands (above). Sparrow-hunting with slingshots was a national past time for children in the 50s.

Factoids: (1) Guava and tomatoes are both banned as offerings to the gods/spirits, because the seeds cannot be digested that might displease those being honored. (2) 芭樂票 refers to a bad check, a kite or a dud, an inevitably bounced check.