Acer glabrum

Washington. Wenatchee NF: Icicle Creek, along south side of River on trail between Chatter Creek and Jack Creek; 47º19.436, 120º34.626",  2825 ft.  Dense riparian forest on nearly level rocky soil with Abies grandis, Thuja plicata, Picea englemannii, Tsuga heterophylla, Pinus monticola, P. ponderosa, Pseudotsuga menziesii, Larix occidentalis, and understory shrubs Acer circinatum, Amelanchier alnifolia, Alnus sinuata, Arctostaphylos uva-ursi, Berberis nervosa, Cornus sericea, Lonicera involucrata, Menziesia ferruginea, Paxistima myrsinites, Rubus parviflorus, Shepherdia canadensis, Rosa woodsii and herbs Smilacina racemosa, Xerophyllum tenax. 12 July 2010.

Acer macrophyllum
CA: Trinity Co., Trinity Lake
11 May 2009. 

Acer glabrum
Lake of the Island,
Marble Mts. Wilderness, CA
July 2006. 

Trees and Shrubs of Kern County (Jan 2013)

Key to Acer

1. Leaves divided into 3 (-9) stalked leaflets; flowers/fruits dangling........... Acer negundo

1. Leaves deeply lobed; flowers/fruits dangling to erect.................................................. 2

2. Leaves large, 10–25 cm across; flowers/fruits dangling in 20–90 in
long cylindrical clusters........................................................... Acer macrophyllum

2. Leaves not more than 7 cm across; flowers/fruits 3–8 on shortly
branched ascending scapes................................................................Acer glabrum

       Leaf blades 1.4–2.8 cm long, 2–3.5 cm wide; lateral lobes with 3–7
  blunt teeth; petioles <2.5 cm......... ............................................. var. diffusum

       Leaf blades 2.9–5.6 cm long, 3.6–6.3 cm wide; lateral lobes with 5–22
  sharp teeth; petioles >2.5 cm......... ............................................. var. glabrum

Acer glabrum Torrey 1827 var. glabrum. [A. glabrum var. torreyi (A. torreyi Greene 1902) Smiley 1921]. Mountain maple.  Type from Rocky Mts., 1,000 ft elev. above the plain [Sheep Mt. about 7 miles southwest of Waterton on the north side of South Platte Canyon, Jefferson Co., CO]. California montane forests to Oregon,  across desert mountains to Rocky Mountains. Kern Co.: Reported by Shevock to be “uncommon to occasional on a dolomite outcrop in a mixed conifer forest west of Piute Mt.”, 7,500 ft, and also a white fir forest in the Inspiration Point Botanical Area at 7,800 ft near the headwaters of Erskine Creek (CCH).

Acer glabrum var. diffusum (A. diffusum Greene 1902) Smiley 1921. Mountain maple. Deciduous shrub or tree to 6 m; twigs reddish; leaves opposite, shallowly to completely divided into three serrated leaflets; flowering Apr–May, appearing with the leaves, in dangling clusters; fruit a pair of thin wings extending from the pericarp body that closely covers the seeds (samarium), similar to a dragon fly, developing from a 2-celled ovary that separates and diverges in part, each with a separate wing.  California desert mountains to central Utah, generally above 5,000 ft.  Type from near the summit of the West Humboldt Mts., NV. Kern Co.: Kern Plateau and Pacific Crest Trail between Owens Peak and Mt. Jenkins, and on the northwestern slope of Spanish Needle about 2.5 miles southeast of Lamont Meadow (CCH).

Acer macrophyllum Pursh 1814. Big leaf maple. Generally along streams throughout most of California except the Great Valley, below 5,000 ft, north to Alaska. Type from Blue Mts. of Oregon. Kern Co.: A small colony occurring along El Paso Creek in the Tehachapi Mountains, and near the summit of Black Bob Canyon in the San Emigdio Range (Twisselmann).

Acer negundo Linnaeus 1753 [includes ssp. californicum (Negundo californicum Torrey & A. Gray 1838) Wesmael 1890]. Box elder. Southern Canada, across the U.S., to South America . Kern Co.:  Occasional along canyon bottoms and creeks from Lebec to El Paso Canyon, also a small colony in upper Jawbone Canyon just above the Wilderness Ranch (Twisselmann).