Hawthorn
The name Hawthorn refers to any plant in an entire genus (Crataegus). Good luck to anyone trying to narrow an individual tree down to its exact species. Depending on which botanist you ask, you'll be told that there are over a thousand species or only one species (or any number in between) of hawthorn. This apple species is native to North America, Europe, and parts of Asia. The features of this tree can vary greatly between subspecies and cultivars. So how can you recognize this common tree?
General Shape
If you have ever seen an apple tree (which is closely related), you'll know the form. The tree itself doesn't get very large, generally, and the angled limbs tend to branch out fairly low. The branches are also bent, and bent again, and bent again, like they can't decide where they're headed. The limbs are thin, and the twigs tend to be rough and knobby. The bark is a dull gray.
Fruits
The fruits vary in size, depending on which hawthorn they're on. Some hawthorns have large apples the size of crabapples, while others bear fruits resembling currants.
Leaves
The leaves vary in shape greatly. Some resemble apple leaves, but nearly all are wider and lobed. Unfortunately the one leaf characteristic that screams "Hawthorn!" is a disease that creates round orange spots on the leaves. Don't worry too much; generally the disease is more of an annoyance than a threat to a healthy hawthorn.
Thorns
Most hawthorns have thorns (hence the name). They can be quite long and thin, and rather annoying to climb through. There are thornless cultivars as well, but they're not common.
Basically, a hawthorn is an apple with attitude. She can rain flower petals upon you, or scratch you for getting too close. She commands a gentle respect and rewards you for it.