<Tr> <Th> Nebraska </Th> <Td> Eastern Cottonwood </Td> <Td> Populus deltoides </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Th> Nevada </Th> <Td> Single - leaf Pinyon </Td> <Td> Pinus monophylla </Td> <Td> </Td> <Td> 1959 </Td> </Tr> <Tr> <Td> Great Basin Bristlecone pine </Td> <Td> Pinus longaeva </Td> <Td> </Td> <Td> 1987 </Td> </Tr> <Tr> <Th> New Hampshire </Th> <Td> American White Birch </Td> <Td> Betula papyrifera </Td> <Td> </Td> <Td> 1947 </Td> </Tr>

How many types of trees are in the us