I was just thinking of this recently, and now that I have a digital camera, I need to go visit it again.
What I'm referring to is the Bald Cypress. This tree is so rare that there is only a single tree in the entire state. Well, a single tree that wasn't planted by man that is. Down in or on the edge of a cedar swamp in Cape May County there is a single lone Bald Cypress. It's described in a book I have that was written in 1910, and also another book I have from the 1980s.

Bald Cypress 5' 11 1/2", in the NJ Natural Lands Trust preserve

The book from 1910- the full title is "Annual Report of the New Jersey State Museum, Including a Report of the Plants of  Southern New Jersey, With Especial Reference to the Flora of the Pine Barrens.", by Witmer Stone, 1910, but published in 1911. I have two copies of it. Woodrow Wilson was governor of New Jersey when this book came out. His portrait is inside. The book is very thick, with 809 pages, not including the index and the photographic plates in the back after the index.
What Mr. Stone says about Bald Cypress in New Jersey is the following:

"Taxodium L. C. Rich.
Taxodium distichum (L.) Bald Cypress.
Cupressus disticha Linnæus, Sp. Pl. 1003. [Virginia and Carolina].-- Beck, Bot. 338, 1833.-- Gray, Manual Ed. 1, 443, 1848.-- Hollick, Rep. on Forests, 181, 1900.

Upon what evidence the Cypress was credited to New Jersey by Beck and Gray I am unable to say, but more recent works have pretty generally excluded our State from its range, or added it with doubt. Search for it in the swamps of South Jersey failed until Mr. H. Walker Hand pointed out a single tree on the edge of Sluice Creek, not far from Dennisville, and informed me of another that formerly grew further down the stream toward the bay. The suggestion has been made that these trees were brought from farther south and planted here, but we can find no positive evidence of this, while very old residents remember them as being large trees in their youth. The locality is peculiarly suitable for Cypress, and, judging by the number of southern plants that have been discovered on the bay side of Cape May County, the occurrence of the Cypress is by no means remarkable. Dr. Arthur Hollick mentions several trees on the salt marsh near Newark, north of our limits,
 which were also alleged to have been introduced, but proof of the fact was not obtainable, while condtions were just such as prevail in the natural habitat of the species. This is the only other occurrence of the tree in an apparently natural condition in the State."
In my opinion, the trees near Newark probably no longer exist. I have seen and photographed the Sluice Creek tree, since I have a book from the 1980s that tells how to find it. About 3/4 of a mile from here there are two of them along a stream bank, a couple hundred yards off of Route 30, but they are behind someone's house, so I assume they were planted at some point.
When I re-scan my photos of the tree I will post them. When I re-visit the tree I will bring the digital camera and the measuring tape.
Barry