Aceraceae / Sapindaceae

Intermountain Flora, v. 3A, p. 308

• 1. Leaves compound.
• 2. Leaves palmately 3-foliolate; leaflets sessile or equally short-petiolulate; autumn foliage bright red; indigenous species, rarely cultivated; a phase with small thichish leaves 1-3 cm wide, from Tooele to the south, is assigned to var. diffusum. Acer glabrum

Acer glabrum	Acer glabrum	Acer glabrum	Acer glabrum	Acer glabrum var. diffusum	Acer glabrum var. neomexicanum

• 2' Leaves pinnately 3-7-foliolate; leaflets petiolulate or at least the terminal leaflet petiolulate.
• 3. Lateral leaflets petiolulate; bark more or less thick and furrowed, not flaky, light brown to gray; flowers appearing with or a little before the leaves; leaflets 3-7; tree mostly 5-12 m tall; autumn foliage yellow; common in our range. Acer negundo

Acer negundo	Acer negundo	Acer negundo	Acer negundo

• 3' Lateral leaflets sessile; bark thin, separating in papery flakes, cinnamon-brown; flowers appearing after the leaves; leaflets 3; ornamental shrub or small tree; autimn foliage yellow to orange, rarely scarlet; native of China. Acer griseum

Acer griseum	Acer griseum	Acer griseum	Acer griseum

• 1' Leaves simple.
• 4. Sinuses between the principal leaf lobes rounded to obtuse, the margins of the lobes within the sinuses entire.
• 5. Main leaf lobes obtuse to narrowly rounded.
• 6. Main leaf lobes with 1 pair of rounded lobes or none; wings of the fruit widely spreading; autumn foliage golden-yellow; native of Europe and W Asia. Acer campestre

Acer campestre	Acer campestre	Acer campestre	Acer campestre

• 6' Main leaf lobes with 2 or more pairs of obtuse to narrowly rounded lobes; wings of the fruit divaricately ascending; autumn foliage yellow to bronze or red; indigenous species. Acer grandidentatum

Acer grandidentatum	Acer grandidentatum	Acer grandidentatum	Acer grandidentatum

• 5' Main leaf lobes acute, often caudate-attenuate.
• 7. Wings of the fruit divaricately ascending; sepals united; petals wanting; petioles with a clear sap; autumn foliage yellow to orange or scarlet; native to E N. America. Acer saccharum

Acer saccharum	Acer saccharum	Acer saccharum	Acer saccharum

• 7' Wings of the fruit widely spreading, more or less horizontal; sepals and petals distinct; petioles with a milky sap; autumn foliage yellow; native to Europe. Acer platanoides

Acer platanoides	Acer platanoides	Acer platanoides	Acer platanoides

• 4' Sinuses between the principal leaf lobes acute, the margins of the lobes within the sinuses serrate.
• 8. Undersurface of the leaves pale green to silvery; planted as shade trees.
• 9. Flowers appearing long before the leaves; inflorescences in dense lateral clusters; native to E N. America.
• 10. Petals present, sepals distinct; leaves incised mostly less than half the blade, lobes broadest at the base; fruit 1.2-2 cm long; barks not especially silvery; autumn foliage scarlet to orange. Acer rubrum

Acer rubrum	Acer rubrum	Acer rubrum	Acer rubrum

• 10' Petals lacking, sepals connate, the calyx merely lobed; leaves incised more than half way to the base, the lobes much narrowed at the base; fruit 4-7.5 cm long; bark of upper branches silvery white; autumn foliage yellow. Acer saccharinum

Acer saccharinum	Acer saccharinum	Acer saccharinum	Acer saccharinum

• 9' Flowers appearing with or after the leaves; inflorescences elongate panicles; leaves pubescent beneath; autumn foliage yellow to brown; native to Europe and W Asia. Acer pseudoplatanus

Acer pseudoplatanus	Acer pseudoplatanus	Acer pseudoplatanus	Acer pseudoplatanus

• 8' Undersurface of the leaves green; flowers appearing with or after the leaves; planted (except A. glabrum) as ornamental shrubs or small trees.
• 11. Leaves 3-(5)-lobed; wings of the fruit ascending, nearly parallel.
• 12. Lateral leaf lobes nearly equal to the middle lobe in size; indigenous species. Acer glabrum

Acer glabrum	Acer glabrum	Acer glabrum	Acer glabrum

• 12' Lateral leaf lobes much smaller than the middle lobe; native to E Asia. Acer ginnala

Acer ginnala	Acer ginnala	Acer ginnala

• 11' Leaves 7-9-lobed; wings of the fruit widely spreading.
• 13. Blades cut more than half way to the base, the lobes narrowed below the middle, long-acuminate; autumn foliage yellow-orange; native to E Asia. Acer palmatum

Acer palmatum	Acer palmatum	Acer palmatum

• 13' Blades cut to about 1/4 the distance to the base, the lobes not narrowed below at the base, short-acute to obtuse; autumn foliage brilliant red-orange; native to the Pacific Northwest. Acer circinatum

Acer circinatum	Acer circinatum	Acer circinatum	Acer circinatum