Which tree has fern-like leaves? Count the divisions first

Midwest and Northeast: honey locust, Kentucky coffeetree, staghorn sumac

Most "fern-like leaves" searches from Michigan, Ohio, Minnesota, Illinois, Pennsylvania and Ontario end at one of these three.

Honey locust is the fern-like tree of Midwestern streets and parking lots. The NC State profile describes alternate leaves 5 to 8 inches long with 15 to 30 oval leaflets about 1 to 1.5 inches each; some leaves are twice-divided with 4 to 7 pairs of side stalks. The small leaflets give the crown its light, lacy shade, and they turn yellow in fall. Wild trees carry stout, three-forked spines 2 to 3 inches long, while thornless selections such as 'Skyline' and 'Sunburst' are the ones usually planted. Reddish-brown, twisted pods 12 to 18 inches long hang on into winter. Honey locust is native to central and eastern North America and is found in Ontario. The locust page separates it from black locust, whose leaflets are fewer and rounder.

Kentucky coffeetree looks like a honey locust drawn at twice the scale. NC State's coffeetree profile gives twice-divided leaves about 3 feet long and 2 feet wide, with 5 to 9 pairs of side stalks and leaflets 1 to 3 inches long. New leaves come out pinkish-bronze in late spring, so the tree is one of the last to leaf out. Only female trees bear the flat, thick, reddish-brown pods, up to 10 inches long. NC State lists the leaves, seeds and pod pulp as poisonous, and warns that the pulp can be mistaken for honey locust's.

Staghorn sumac is a large shrub or small tree that forms colonies along roadsides and woodland edges. The NC State profile describes once-divided leaves 16 to 24 inches long with 11 to 31 toothed, lance-shaped leaflets 2 to 5 inches long, and young twigs covered in reddish-brown hairs, like a deer's antlers in velvet. Female plants carry upright clusters of hairy, bright red fruit. It grows from Quebec, Ontario and Minnesota south to Georgia. The cut-leaf cultivars sold as 'Laciniata' and 'Tiger Eyes' have the most fern-like leaves of all.

The South, Florida and California: mimosa, jacaranda, royal poinciana

Here the fern-like trees usually have showy flowers, and the flower color is the shortcut.

Mimosa (silk tree), pink. The NC State profile describes leaf stalks 10 to 20 inches long lined with pairs of side stalks, 4 to 6 pairs on young trees and 20 to 30 on mature ones, each carrying 10 to 20 leaflets about 3/8 inch long. The leaves fold down at night and in rain, and the leaflets close when touched. The leaves drop after the first frost without changing color. Mimosa is native to Asia and is listed as invasive by the NC Invasive Plant Council, as NC State notes. The mimosa page covers it in full.

Jacaranda, lavender-blue. UF/IFAS gives twice-divided leaves 9 to 18 inches long, with primary leaflets about 5 inches long and around 20 secondary leaflets about 1/4 inch each. It flowers from April to August, mostly in May, and leaves round, flat, hard brown capsules about 3 inches across. UF/IFAS does not consider it a problem species in Florida and gives USDA zones 9B to 11.

Royal poinciana, red or orange. The UF/IFAS fact sheet describes leaves 8 to 20 inches long with 10 to 20 pairs of primary leaflets, each with 25 to 35 pairs of secondary leaflets about 1/2 inch long: the finest-cut leaf on this page. Flowers cover the crown from May to July, followed by dark brown pods 1 to 2 feet long. It grows outdoors only in zones 10B to 11, so in the US it is a south Florida, Hawaii and Puerto Rico tree.

Long leaves that smell: tree of heaven, the sumac look-alike

A fast-growing tree with very long once-divided leaves, on a vacant lot or a highway verge, may be tree of heaven. The NC State profile gives leaves 18 to 24 inches long with 10 to 41 leaflets. The test: each leaflet is smooth-edged except for a notch or a few teeth near its base, and a crushed leaf smells foul, some say like peanut butter. Staghorn sumac's leaflets are toothed all along the edge and its twigs are velvety. NC State calls tree of heaven a non-native invasive tree, reported invasive in 30 states and Hawaii, and a host for the spotted lanternfly. The tree of heaven page has the full leaflet-gland test and the walnut and ash look-alikes.

Soft needles that look like a fern: bald cypress

If the "fern" is a tall conifer by a pond or in a parking lot island, it is probably a bald cypress. The NC State profile describes flat, linear needles 1/4 to 3/4 inch long in two rows along each branchlet, giving a soft, feathery look. Unlike most conifers it is deciduous: the needles turn orange to cinnamon-brown and the whole branchlets drop in fall, leaving the tree bare in winter. Knobby "knees" rise from the roots when it grows in or near water, and round, wrinkled cones 3/4 to 1 inch across show in October. It is native from Delaware to Florida and west to Texas, and planted much farther north. Dawn redwood, a Chinese conifer planted in parks, looks almost the same; the bald cypress page sets the two side by side.

Not a true fern-like leaf: cut-leaf Japanese maple

Laceleaf Japanese maples have simple leaves, not compound ones, but the lobes are cut so finely that the leaf reads as a fern frond. Check the twig: Japanese maple leaves grow in opposite pairs, and each leaf, however lacy, joins the twig with one stalk. A compound leaf of a honey locust or mimosa has a long central stalk with many separate leaflets.

Using a photo

A single leaf laid flat on a pale background, with a flower or pod beside it if there is one, is the photo that helps most. Tree Identifier names a tree from one photo, and honey locust, mimosa, jacaranda, royal poinciana, bald cypress, dawn redwood and Japanese maple are among the species in its Collection. It shows no confidence score or list of alternatives, so check the answer against the leaflet sizes in the table. The follow-up chat under each result can answer questions such as how a honey locust differs from a Kentucky coffeetree, and the Tree Map remembers where the tree stands so you can come back when it flowers.