Subspecies of A. saccharum? USDA treat it as a species: http://plants.usda.gov/java/profile?symbol=ACGR3
I have been following the accepted taxonomic divisions as last reported by de Jong (2002), a coauthor of Van Gelderen et al., Maples of the World (Timber Press 1994). De Jong, Piet C., Worldwide Maple Diversity, Proceedings of the International Maple Symposium 2002: 2-11. Section Acer Series Saccharodendron has one species – saccharum, which has seven subspecies. From Van Gelderen (1994), this taxon is Acer saccharum ssp. grandidentatum (Torrey & Gray) Demarais (1952). Interestingly, two other USDA sources - Integrated Taxonomic Information System and Germplasm Resources Network - list the taxon as Acer saccharum ssp. grandidentatum (Nutt.) Desmarais. Photographs: late March 2006; early April 2006; late May 2006; young specimen, private collection.
Acer saccharum ssp. grandidentatum Idaho Botanical Garden, Boise, ID; July 2006. A beautiful photograph of a leaf of this species in October taken in the UBCBG Alpine Garden is at: www.botanicalgarden.ubc.ca/potd/2005/07/acer_grandident.php. Bigtooth maple has a spotty distribution, occurring in mountainous areas from southeastern Idaho and western Wyoming south to Arizona, New Mexico, western Texas, and northern Mexico. It is most common along a north-south axis from southeastern Idaho to central Utah, where it may form nearly solid stands. Farther south, bigtooth maple occurs as isolated populations in numerous isolated mountain ranges. http://www.fs.fed.us/database/feis/plants/tree/acegra/distribution_and_occurrence.htm.
Here are some more "Big Tooth Maple" photos from the San Antonio Botanical Garden taken 8-24-07. Note that this specimen was not identified as var. sinuosum so I presume it is acer grandidentatum var. grandidentatum or acer saccharum ssp. grandidentatum var. grandidentatum if you prefer. Note that the foliage looks different than the other poster's. And interestingly, the Big Tooth I have in my yard is morphologically intermediate between the two - it has many leaves similar to these and some more like the other posters. Also note that this specimen is more compact than usual - I speculate because it's in an exposed situation. I've seen some minimal scortching on this species in Texas when it gets too much hot afternoon sun.
Time to return this thread to being titled Acer grandidentatum, the Acer saccharum subspecies have all been split off again in the new Maples list ;-)
