New Mexico Plants: Soapberry Family



Photos are organized by genus and species. I provide an extended essay for the first species, Rocky Mountain maple. If you're not interested, just scroll past that entry to the other species. You can hover over photo series with your cursor to control the images.

Identifying Rocky Mountain Maples (Acer glabrum)

Rocky Mountain maples are a common species in the mountain West. They form shrubs or trees up to 30 feet (10 m) tall. At first I struggled to distinguish them from boxelders, which are also in the genus Acer, and others may have the same problem, so I'll dive deeper than usual.


First off, what doesn't work for distinguishing Rocky Mountain maples from boxelders: seeds with two prominent wings (samaras) and reddish new twigs and leaf stems. You can find those on both. A better starting point is the leaves, but with a proviso. In folk taxonomy, a maple leaf is supposed to be continuous and to have three main points (as in the Canadian flag and the bigtooth maples shown below). If, instead, each leaf consists of three pointed leaflets, each on its own "mini-stem" (petiolule), that's "supposed to be" a boxelder leaf. Now to explain why I think the photos shown above are of Rocky Mountain maples, despite many boxelder-type triple leaflets. If you need to work this issue out for yourself, the trees are at Capulin Spring in the Sandia Mountains. 


As the SEINET page for the species shows, you can find three-leaflet leaves on Rocky Mountain maples along with more maple-looking leaves. Based on the trees I've seen, you might be hard-pressed to find a classic maple-type leaf on a local Rocky Mountain maple. But keep looking and you'll see that for some leaves on a tree, the apparent leaflets are in fact a single three-pointed leaf. The following notes are keyed to three of the photos.


Note 1: a quick glance suggests that these leaves are dominated by a three-leaflet structure, not the classic maple leaf shape. But look closer.


Note 2: a blowup of part of the photo labeled "See Note 1." To the left is a three-leaflet leaf but the other leaves are three-point leaves, only more deeply notched than you'd expect on a maple leaf.


Note 3: this blowup shows a different part of the photo labeled "See Note 1." Again, deeply notched single leaves, not separate leaflets.


You can also see that when there are separate apparent leaflets, they spring directly or almost directly from the main "leaf stem" (petiole), as opposed to growing from boxelders' fairly long "mini-stems" (petiolules).


What else? On a mature trunk, Rocky Mountain maple bark is smoother than boxelder bark. Also, Rocky Mountain maples tend to be found at higher elevations (7000–9000 feet; 2130–2740 m) than boxelders (3000–7500 feet; 910–2290 m). The trees at Capulin Spring are at about 8800 feet (2680 m), so within the elevation range for Rocky Mountain maples, but not for boxelders.


Let's apply those lessons to a different Rocky Mountain maple, which I found at the crest of the Sandias.


Again, my first impression was of a shrub with three-leaflet compound leaves, but a closer look showed showed that some leaves were whole, yet deeply notched. After a search I found one classic maple leaf, and took pictures of both sides of it.


Bigtooth Maple (Acer grandidentatum)

The biggest concentration of Bigtooth Maple in the Albuquerque area is at the Fourth of July Canyon campground and on the slopes above. Each fall, many Burqueños make the pilgrimage to see the best fall colors around. For a hike that takes in those colors, click here.


Boxelder, Box Elder (Acer negundo)

Look for a leaf consisting of three pointed, toothed leaflets. In the fall, look for the two-winged seeds characteristic of maples. For more detailed ID notes, please see my narrative on Rocky Mountain maples, above. For a hike that takes you to a stand of boxelders, click here.


Golden Rain-Tree (Koelreuteria paniculata)

Golden rain-trees are popular plantings in Albuquerque (and around the world) thanks to their showy flowers, striking fruit, and thick, shapely canopies. The complicated scalloping of the edges of the compound leaves will help with the ID. A few have escaped, hence their inclusion here.


Tropical Soapberry, Amolillo (Sapindus saponaria)

A tree of the southern Plains, west into New Mexico and Arizona and south into Mexico. According to the SEINET web page, it's also known as wingleaf soapberry, western soapberry, or just plain soapberry. Besides amolillo, the Spanish names include abolillo, jaboncillo, boliche, chirrión, amole, guayul, palo blanco, and the intriguing mata muchacho.