London and Labrador are at the same latitude, yet why do palm trees grow in London?
The answer lies in the oversimplification of latitude as the only factor in natural environment for vegetation. First, the palm trees in London did not spring up from a wilderness, and would not flourish without the man-made environment supplied and maintained for them year-round. Second, such factors as moisture, ground acidity, and extremes of temperature must be factored in. Florida, for example, has a constantly moist atmosphere as well as plenty of sunshine, but even there they are not “native” to that climate, but are sustained in civilization. Labrador’s climate allows for occasional extremely low temperatures, anathema to palms, while England’s climate rarely sustains low temperatures, partly because of the neutralizing effect of being surrounded by the ocean, and partly because of England's relatively low altitude. Labrador’s climate generally is too cool to support full tree growth; precipitation is also minimal, mountain ranges affect the precipitation, and the climate is more arctic than temperate.