Interstate-5 runs the height of the United States beginning at the Canadian border in Washington and ending at the Mexican border in California. If you have driven on this highway anywhere from Washington to northern California, you have probably, at one point, looked out the window and unknowingly seen many trees or shrubs that go by the name Crataegus monogyna or are commonly known as the oneseed hawthorn.
Beautiful but dangerous
In the mid to late spring, the tree produces beautiful clusters of white blossoms. In the late summer and early fall, each tree produces many of clusters of small red fruits and can be quite striking. Because of its aesthetics, the oneseed hawthorn was intentionally introduced into the United States from Europe as a cultivated ornamental tree. They are dangerous from both a biological and physical standpoint. According to the USDA, it is considered invasive in the lower 48 states, Alaska, and Canada and can be propagated through cuttings and roots, but predominantly through seeds. One notable environmental impact of the invasive oneseed hawthorn trees is its competition with native flora for space and nutrient resources. In addition, oneseed hawthorn branches are aptly named because they produce haws and are covered in thorns.
A non-native intruder followed by a native pest
Shortly after its introduction to the west coast of the United States, oneseed hawthorns became infested with an agricultural pest native to the eastern United States, Rhagoletis pomonella, otherwise known as the apple maggot. The native range of the apple maggot has been documented to include Mexico and the southern and eastern United States. However, it has recently been hypothesized that the apple maggot could also be native to the western United States and Utah, historically infesting the native river or black hawthorn, Crataegus douglasii Lindl, and has recently made the host shift to the oneseed hawthorn after its introduction. Oneseed hawthorn fruits can become heavily infested with apple maggots, but this does not necessarily preclude invasivory!
Eating oneseed hawthorn
The USDA PLANTS database indicates that oneseed hawthorn fruits are not palatable to humans. This may be so, but with a little preparation, it can become quite a tasty jelly! When collecting oneseed hawthorn fruits, be careful of the thorny branches and keep the fruit and peduncle intact to prevent premature spoilage. Unfortunately, it is currently mid-April and the fruits will not yet be ripe and ready for harvest for a few months, so check back in the future for a tutorial on how to make oneseed hawthorn jelly.