As the rainy season becomes the dry season in November or so it's a pretty thing to see big, round, yellowing grapefruits in dark green trees beside shady village homes. That's a typical cluster above. Grapefruits, like oranges and lemons, are citrus fruits, which means that they belong to the genus Citrus. Grapefruit trees are Citrus x paradisi. A Grapefruit's typical citrus leaves with "winged petioles" causing the leaves to look jointed at their bases are shown below:
A sliced-open grapefruit typical of the kind found around Maya homes has a thicker rind and more seeds than those in supermarkets up North, as shown below:
With that fruit's thick rind, many seeds, and relatively dry flesh, you might wonder whether grapefruit trees around homes in Maya villages today might derive from stock brought to the Yucatan by the Spanish during colonial times, long before plant breeders produced cultivars with thinner rinds, fewer seeds and juicier flesh.
In fact, I'll bet that the Yucatan's little Maya villages are great places for finding old strains of many cultivars, maybe strains going extinct out in the world as flashier ones take their place. And maybe some of those old strains have resistance to diseases, or offer flavors or textures, which newer cultivars don't.
We've seen that the technical name for the Grapefruit tree is Citrus x paradisi. The "x" in the name's middle signifies that we're dealing with a hybrid. In other words, there's no "Wild Grapefruit" out in the wild from which today's grapefruit plants have been developed.
The first grapefruits came into being in Barbados in the 1700s when an Orange tree, Citrus x sinensis, was crossed with a Pomelo, Citrus maxima, both taxa originally being from southern Asia. And with that x in the Orange's name, you can see that Orange plants themselves are hybrids.
Studies show that compounds in grapefruit increase the effective potency of certain medicines, particularly those known as statins. This came to light when several deaths from overdoses occurred among people on medication who ate grapefruit. Grapefruit juice also can interfere with etoposide, a chemotherapy drug, as well as some beta-blocker drugs used to treat high blood pressure, and cyclosporine, taken by transplant patients to prevent rejection of their new organs.
Grapefruit juice is powerful stuff!