AMMAN, Jordan — It’s a quiet day in Omar al-Faisal Park, in the impoverished industrial outskirts of Jordan’s capital, Amman. Sandwiched between the runway of a military airport and residential streets, the park seems unimpressive at first glance, but it shelters a little-known gem. Behind a wire fence, trees neatly planted a few meters apart give way to a dense flurry of branches and tangled shrubs. Compact soil has been replaced by a thick mix of straw, earth and decomposing weeds. In spring, dozens of wildflowers blossom along the edges of the garden, swaying to the gentle hum of beetles an…