Acer grandidentatum (bigtooth maple)

Image Source -

Intermountain Flora
Small, scrubby tree or arborescent shrub, mostly 4-8 m tall, the trunks commonly 2 or more together and ascending rather than strictly erect; leaves dark green above, paler and persistently villous or villous-puberulent beneath, especially along the main veins, rarely eventually subglabrate above except for lines of minunte, thick, glandular hairs when very young, mostly 5-11 cm wide, turning yellow to bronze or red in the autumn, palmately (3) 5-lobed to about the middle or a little beyond, the lobes with a few coarse, blunt teeth or lobules, varying to sometimes virtually entire, the central leaf lobe usually (not always) wider near or a little above the middle (at the level of a pair of lobules or large teeth) than at the base; flowers small, borne in loose, corymbiform to subumbelliform clusters from a preformed lateral buds (these often terminal to short spur branches) that may produce a pair of leaves in addition to the inflorescence the pedicels slender and elongate, drooping, mostly 1.5-3 cm long, beset with few to fairly numerous long, loosely spreading hairs at least distally, especially about the base of the flower; sepals 2.5-5 mm long, pale, broad, broadly rounded above, connate to form a shallowly to deeply (and often irregularly) lobed cup, beset with some long hairs like those of the pedicel, at least around the distal margins; petals none; disk extrastaminal; stamens mostly 8; ovary and young fruit beset with long straight hairs; mericarps of the samara each mostly 2.5-4 cm long and 1-1.5 cm wide at the widest part, the seed-bearing basal portions widely divergent, the wings subparallel to more often spreading at a narrow to fairly wide angle.

Cronquist, A., Holmgren, N.H., and Holmgren, P.K. (1997) "Intermountain Flora" pg. 312, vol. 3 part A, The New York Botanical Garden New York.