Shrub put in particular island area (10)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

POINT, I, A, with SET = put inserted. Particular can be a noun meaning a point, e.g. a detail on a form. An example of this (originally Mexican) plant appears every Christmas in our house, the red and green one, but I’d have spelt it wrongly if you asked me before this clue; it’s not pointsettia, it’s apparently named after an American chap called Joel Robert Poinsett, who was US Minister to Mexico in the 1820s.