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|Family: Sapindaceae||View Description||Dichotomous Key|
|Genus: Acer||View Description||Dichotomous Key|
|Species:||View Description||Dichotomous Key|
Acer glabrum Torr.
Habit: Shrub, small tree, < 6 m; dioecious (or staminate plant with some bisexual flowers). Leaf: 3-lobed (or 3 sessile leaflets) 1/4--3/4(1) of leaf length, at least outer side toothed, teeth 3--22, acute to obtuse; abaxial surface pale green, glabrous. Inflorescence: terminal, ascending, flowers 3--8, appearing after leaves. Flower: petals 2--3 mm, +- = sepals. Fruit: wings spreading (0)70--120°, rarely touching, parallel.
Unabridged Note: Acer glabrum is a very variable sp., but the pattern of variation is confusing. The species has been divided into as many as six varieties, but most of the variation probably results from local selection and clinal variation, not divergence that can be recognized taxonomically. Justice (1995, 2002) follows some earlier authors in restricting the name Acer glabrum var. glabrum to Rocky Mountain populations, and separating populations from California and southern Oregon as var. torreyi (Greene) Smiley based on supposed differences in the venation and form of the lobe apex and marginal teeth (var. glabrum with leaf lobes and marginal teeth acute, and fine venation clearly visible and forming regular areoles, and var. torreyi with leaf lobes and marginal teeth usually broad and apically rounded, and fine venation "somewhat obscured" and less regular). I find these characters more variable in both regions than Justice's accounts suggest. There are no constant differences between plants from the two regions, however. Plants from around the type locality in Colorado tend to have short-acuminate lobes and long, sharply acute teeth, but some California specimens approach this morphology (especially from the Klamath region), and California specimens with acute teeth and lobes are fairly common (especially in the Klamath region). Plants from Wyoming, Utah, southeastern Idaho and southernmost Montana generally have blunt teeth and lobes, and are generally indistinguishable from California specimens. Given the variability of these characters and the absence of consistent differences between the named taxa, I see no valid basis for excluding California plants from var. glabrum. Some older references key all plants with compound leaves to var. neomexicanum (Greene) Kearney & Peebles. Compound leaves do occur rarely in California, but these plants are not referable to var. neomexicanum which is found in CO, New Mexico. Justice (1995, 2002) gives characters that define the variety adequately. Acer glabrum var. douglasii (Hook.) Dippel is found from northern and eastern Oregon, southern Idaho, south-central Montana north to southern Alaska. This variety has been reported for California, but all specimens seen named as var. douglasii from southern of Lane County, Oregon have been misidentified. Acer glabrum var. douglasii differs from our California plants as follows:
eFlora Treatment Author: Alan T. Whittemore
Jepson Online Interchange
Previous taxon: Acer circinatum
Next taxon: Acer glabrum var. diffusum
Citation for this treatment: Alan T. Whittemore 2017. Acer glabrum, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=11736, accessed on April 27, 2017.
Citation for the whole project: Jepson Flora Project (eds.) 2017. Jepson eFlora, http://ucjeps.berkeley.edu/eflora/, accessed on April 27, 2017.