I have bought a Chaenomoles plant which appears to be doing well and I have noticed what resembles a small apple is hanging off the end of one branch. What is this and should I do anything?
That would be the reason that Chaenomeles were an early favorite of farmers when it was first introduced into the U.S. -- that fruit is actually edible when it ripens in the fall. This article contains more information about Chaenomeles fruit:
Read more at Gardening Know How: Flowering Quince Care: How To Care For A Japanese Flowering Quince https://www.gardeningknowhow.com/ornamental/shrubs/flowering-quince/japanese-flowering-quince.htm