Eastern Prickly Pear Cactus (Opuntia cespitosa)

 This is the much less common cactus of the Jersey Shore. It has flowers with red centers (always). It can have spines or not. Pretty much all cacti with spines are this, but it can also completely lack spines. Its areoles (the dark spots) have lots of spiny hairs that should be relatively easy to see. 

If the flowers are entirely yellow it should be O. humifusa instead, the more common species. 

Note that there are two weird species of Opuntia on Long Beach Island and Brigantine. One has tiny pieces to it and the other is very upright not sprawling as here. 

East Coast Prickly Pear Cactus (Opuntia humifusa)

 This is the more common cactus on the dunes in NJ. Its flowers have no red in the center. It never has any spines. Its areoles (the dark spots) should not have much in the way of obvious spined hairs (but this is subtle) In the photo here it has little branches in the areoles but not much in the way of the hairs. 

If it has red in the flowers or any spines it is probably O. caespitosa. On Long Beach Island and in Brigatine there are two weird rare (for NJ) Opuntia species.

Christmas Cactus