What type of wood is pressure treated deck lumber made from?

Question

I've been redoing the decking floor and buying 5/4 x 6" premium pressure-treated boards from the local big box stores (HD or Lowes). It's not of great concern but I'm interested in what type of wood these boards are made of? I did some searching and think it may be cedar or pine. The stores do not indicate the type. There are the stamp markings but it doesn't tell me much. I bet someone savvy with wood could just tell from the grain.

When I buy these boards, what type of wood is typically used and can it vary?

Answer 1

Grade stamp says SYP == Southern Yellow Pine. Sometimes known as "hard pine" for reasons that become obvious when you use it and other kinds of pines.

Ones with other grade stamps would be other woods. SPF is the terribly unhelpful "Spruce, Pine, or Fir" where "Pine" would mean White Pine or perhaps(?) Red Pine, but not Southern Yellow Pine.