Sunday, April 14, 2024

South Dakota Maples—Sugar, Silver, & a Trickster

Sugar Maple in Sica Hollow, northeasternmost South Dakota.

For April's tree-following report I'm sticking with my strategy of following (learning about) South Dakota trees—helpful in preparing our guide to trees and shrubs of the state. This month I chose maples, of which there are three.

South Dakota is not known for its trees. It's largely a prairie state, though much of what was prairie is now fields of corn, wheat, soybeans, hay, sunflowers and more. Most people who visit (i.e., tourists) head straight for the Black Hills in the far west, which are mostly covered in coniferous forest (that's why they look black).

But far eastern South Dakota also is forested. It's part of the immense Eastern Deciduous Forest (EDF) ecoregion, which covers the eastern third of the United States and extends into southeast Canada and northeast Mexico.
Globally, the North American EDF is one of the largest parts of the Temperate Broadleaf Forest Biome (yellow green). Source.
Authorities frequently claim that the EDF reaches its western limit in Minnesota, but they're wrong. It continues into South Dakota where it's best developed in the southeast and northeast corners of the state.
South Dakota land cover. Dark green units in the southeast and northeast are large stands of Eastern Deciduous Forest (modified from Johnson & Knight 2022).
EDF thrives where summers are warm and moist and winters are cold, as is the case in easternmost South Dakota (summers are increasingly dry going west). As the name indicates, the dominant trees lose their leaves each winter. These include oak, elm, basswood (linden), hackberry, and maples.
Eastern Deciduous Forest in northeast South Dakota, with a thick understory of young Sugar Maples hoping to reach the sky.
Of the three maple species in South Dakota, two are native to the far east—Sugar Maple and Silver Maple. However Silver Maple is widely planted, and escapees are occasionally found in the wild as far west as the Black Hills. The botanists who described and named these maples long ago chose very similar scientific names: Acer saccharum and A. saccharinum (thanks, guys, I hope I can keep them straight!). Both mean sugary, referring to the sap (Saccharum is the genus name for sugarcane). However the Sugar Maple's sap is far sweeter (Plant Finder, Missouri Botanical Garden).

These two maples are similar in appearance, enough so that some effort is needed to tell them apart. Both have what we think of as typical maple leaves—palmately lobed, like the fingers of a hand. Fortunately the details differ, which is more easily shown with photos than explained with words. But we intend to do both.

Leaves of Sugar Maple are more shallowly lobed with broader sinuses (gaps) between the main lobes. The sinuses usually are less than half the overall leaf length and are rounded at the bottom.
Sugar Maple, Acer saccharum (Minnesota Wildflowers Information).
Leaves of Silver Maple are more deeply lobed, and with narrower sinuses between the main lobes. The sinuses usually are at least half the length of the leaf and are more pointed at the bottom.
Silver Maple, Acer saccharinum (MWI).
Both trees develop furrowed ridged bark with maturity, but that of the Silver Maple is more flaky, enough to make it look shaggy ... or so they say. Do you have tips for telling these two maples apart? If so, please leave a Comment below.
Sugar Maple, Acer saccharum (MWI).
Silver Maple, Acer saccharinum (MWI)—a bit shaggy?
Now for those readers about fall off their chairs with curiosity ... there is indeed a third maple in South Dakota. But it's a trickster.
Yes, this IS a maple!
It's a maple with lobes so deep that they're leaflets.
This is Acer negundo, the Boxelder—also known as Ashleaf Maple (ash has similar leaves), Manitoba Maple, Γ‰rable Γ  feuilles composΓ©es, and Poison Ivy Tree (not poisonous but leaflets are similar in shape). Instead of palmately lobed leaves typical of maples, it has pinnately compound ones—divided into paired leaflets with one more at the tip.

In contrast with Sugar Maple and Silver Maple, which are uncommon in South Dakota and limited to the far east, Boxelder is common and widespread across the state, and apparently not terribly picky about habitat. Some call it a weed.
The Boxelder I followed in 2018—a bit of wildscaping for this warehouse.

This is my contribution to the monthly gathering of tree-followers kindly hosted by The Squirrelbasket. More news here.

Sources cited

Johnson, W. Carter, and Knight, Dennis H. 2022. Ecology of Dakota Landscapes; past, present, and future. Yale University Press; Biodiversity Institute, U. Wyoming. ISBN 978-0-300-25381-8.

Thursday, March 14, 2024

South Dakota Tree-Following—Prairie Crabapple

Pyrus ioensis. 1913, Curtis's Botanical Magazine. Source.
This month's tree-following report features another tree from South Dakota, part of my effort to learn more about the state's trees. There's a practical reason for this—I'm writing species descriptions and selecting photos for an online Guide to Trees, Shrubs, and Woody Vines of South Dakota.

Having recently worked my way through the challenging Rose Family (see post about the diverse and complicated fruits), a Rosaceaous tree was the obvious choice. I picked one new to me—Prairie Crabapple, Malus ioensis (formerly Pyrus ioensis).

I also wanted to showcase photos from Minnesota Wildflowers (now includes all plants not just wildflowers). It will be a major source of photos for our guide as our states share many species. Almost all their photos are free for non-commercial use (that would be us!), there are tens of thousands to choose from, and the photographers are botanists who know what's needed for identification. The Prairie Crabapple is a fine example (photos below are from the website).

Prairie Crabapples grow as shrubs or trees to 6 m tall, and can form dense thickets from root suckers.

Malus ioensis in bloom, hence the pinkish tinted crowns.
Prairie Crabapple leaves by Katy Chayka, creator and driving force of Minnesota Wildflowers.

With maturity, bark develops irregular ridges or plates that peel away to reveal reddish inner bark.
Prairie Crabapple flowers are typical of the Rose Family, with five showy-but-simple petals surrounded by five sepals. Inside the petals are numerous pollen-producing stamens surrounding a pistil containing ovules awaiting fertilization to become seeds.

Flower bud showing fuzzy sepals. These help with id.
Botanically speaking this crabapple is "armed", in this case with short branches that become sharp-tipped. Technically these are thorns, which are derived from branches or shoots (vs. spines which develop from leaves, and prickles which develop from the outer layer of a stem or branch; there's a Wikipedia article devoted to this topic).
Thorn developed from short flowering shoot.
Fruits of crabapples are pomes, from Old French "pome" meaning apple. Those of Prairie Crabapple are only about 2.5 cm across. They are "edible but barely so" according to Katy.
I'm looking forward to seeing Prairie Crabapple in the wild, of course! But there's a problem. Though multiple sources report it for South Dakota, I found NO specimens in a search of SEINet, the online portal to digital herbaria across the country. And the South Dakota Natural Heritage Program, which tracks rare plants, lists it as "Reported for woodlands of e SD, no vouchers yet found." I may be off on a treasure hunt once spring comes.
USDA Plants shows Malus ioensis in Lincoln, Clay, and Codington counties in South Dakota. Unfortunately no evidence or sources are provided (arrows added).

This is my contribution to this month's gathering of Tree Followers, kindly hosted by The Squirrelbasket. Once again—if you're looking for a good time, I invite you to join us!


Minnesota Wildflowers. Malus ioensis (Prairie Crabapple).

Flora of North America, Malus ioensis.