What kind of flower is this?

It is definitely a Flowering Quince. Perhaps Cydonia japonica rubra?!? I have 2 planted in a front yard flower bed at my home! I enjoy them a lot. Has yours ever gotten fruit on them?

Looks like a flowering Quince to me, Chaenomeles. No clue as to the hybrid. Flowering Quinces are fun to confine in small pots and whack into bonsai shapes.

It's not a quince it's the flower of a pomegranate.(Punica granatum)

You might have a Pomegranate bonsai. Type pomegrante on google images.

That, my friend, is a Flowering Quince shrub.

looks alot like a quince. i am pretty sure most quinces have thorns though

It's quince (Chaenomeles), a shrub:

http://en.wikipedia.org/wiki/Flowering_quince

http://plants.usda.gov/java/profile?symbol=CHSP12

http://www.floridata.com/ref/C/chae_spe.cfm

It looks like a mandeville or in that family.