I'm not sure why so many of the flowers are turning brown and shriveling up. I suspect it's a disease or insect damage because other flower pictures on the internet don't show anything similar.

The plant at hand is a shrub or small tree commonly and weedily growing throughout humid, lowland Central America and southern Mexico. It's CASEARIA NITIDA, for which I can't find an English name. It's a member of the Flacourtia Family, the Flacourtiaceae, a family practically unknown to temperate plant-lovers but well represented in tropical regions. Casearia nitida is such a modest-looking, Plain Jane kind of tree that I wouldn't have bothered bringing it to your attention but for one thing:

If you hold one of its leaves up against the sun, you see the interesting details revealed below:

There you see a typical leaf's venation, but within the green areas between veins, the "lacunae", you see lots of bright dots and streaks. Several plant families display such dots -- the Citrus Family (Rutaceae), the Myrtle Family (Myrtaceae) foremost among them. However, those curved streaks are extraordinary. Botanists say that such translucing points are "pellucid." This pellucid dotting and streaking is fairly common in the Flacourtia Family.

Usually pellucid dots are glands filled with aromatic oils. Crush such leaves and typically they emit a pungent fragrance. Casearia nitida's leaves aren't particularly fragrant, though. Still, I suspect that they're filled with chemicals anathema to insects.