This shrub has been in the yard forever & I've never known what species it is:
formatting link
would seem to be some kind of Crataegus species or Hawthorn, but there are other rose-family trees, even some Prunus, which get just as thorny, & I've just never been certain. Here's another shot of it showing the leaves better:
formatting link
comparing it to a common Russian hawthorn the differences are many:1) It has smaller-than-average white flowers in May, & they are inconspicuous compared to similar blooms of Russian hawthorns, chokeberry, &c.
2) It has regular-looking hawberries except slightly compressed rather than round.
3) It has elongated leaves rather than ferny or lobed as most hawthorns.
Other traits:
1) The thorns are a good two inches long & sharper than the dickens
2) It is an old shrub but only about twelve or fifteen feet tall, so not something that ever becomes a tree.
3) This one has a vase-shaped multi-trunked
-paggers