Ask Mr. Smarty Plants

In order to make a positive ID we would need a photo of the plant; if you could send one that would be ideal.  Otherwise, when faced with an id question like this one the description gives us enough clues that we can make some guesses and provide links to our Native Plant Information Network so that you can zero in on the plant yourself.

However, in this case, you haven't provided enough clues.  I think you are right that it is not Mahonia as that plant is quite coarse in texture with leathery, prickly holly-like leaves and the berries are definitely not in a cone-shaped cluster.  There is no Mahonia native to New Jersey but there are a couple that are available in the nursery trade in your area: Mahonia repens (creeping barberry)and Mahonia aquifolium (hollyleaved barberry) Both of these are native to the west and have purple berries resembling grapes.

As I gloss through the database, searching for plants that are native to New Jersey, the only one I come across that has red berries borne in that manner is the Sambucus racemosa var. racemosa (red elderberry).  That guess is a real stab in the dark and I would be amazed if that is your mystery plant.

Have a look through the NJ plants and if you don't find it but can provide a photo and more information about the plant, we'd be happy to give it another try. Instructions for submitting photos are on the Mr. Smarty Plants plant identification page.

Mahonia repens

Mahonia aquifolium

Sambucus racemosa var. racemosa