A coconut rolls down a beach, get carried away from shore by the outgoing tide, washes ashore on a faraway island weeks later, a
nd sprouts into a coconut palm tree. Years later, coconut palms are abundant along the shoreline but rare up the slope of the volcano that occupies the middle of the island. What kind of physical barrier may be preventing coconut palm seeds from dispersing to higher ground?
The official USDA hardiness zone of the Coconut is 10a (meaning it can handle temps of 30-ish Fahrenheit VERY briefly, and can also be seen in very small microclimates in 9b parts of Texas and Florida) but that is only with hot humid summers. In California, the places that have proper moisture and suitable winter temperatures (10a or higher) do not have high enough summer temps. If summer temperatures do not reliably reach 80F or higher, then a Coconut Palm will only live for a few years before it is irreversibly weakened by not having the proper level of sugars built up in its roots, which become malformed and underdeveloped by the lack of ground heat
