Ask Mr. Smarty Plants

Well you have me confused. Because your question came from Oregon, I am assuming you are talking about a river in Oregon, but Google thinks the Hudson River is in New York and Wikipedia says there is one in Georgia as well as New York, but not Oregon.

So ... here's how you find the answer to your question.  Visit our Native Plant Database, scroll down the page and perform a Combination Search for whichever state you are thinking of. You will have to do separate searches for trees, shrubs, herbaceous plants and grasses, each time narrowing the search to the conditions you would find along/in a river (moist and wet).  A list of plants will be generated with links to detailed plant information pages.  Those pages are linked to the USDA website, where you can see in which states and counties the plant is present (not necessarily native, but present).

For example:

When I search: Oregon/shrub/moist /wet, a list of 90 plants is generated.

Amelanchier alnifolia (Saskatoon serviceberry) is one of the first ones on the list. When I click on it's USDA symbol AMAL2 it takes me to this page on the USDA site which shows me that the plant is present in a lot of the US and Canada.  It is present in every county in Oregon but not New York.

This is a fairly involved process and I recommend that before you start you do more general  internet search on riparian plants for the state or area in which your Hudson River flows. Here's a link to a field guide for riparian plants of New Hampshire which may be helpful if you are referring to the NY Hudson River, as the plants will likely be native to New York as well (you can verify on our database). Keep in mind that our database will give you only native plants.  There will be many non-native and invasive plants present in the river as well.  You will find information about invasive plants as well as recommended native replacements at this Gardensmart website.

I hope this guidance is helpful; your question is too broad to be able to give you a concise answer with a list of plants.