Which tree has white flowers? Start with the month

Callery pear: the one that smells

If a white-flowering tree along a road or parking lot smells like rotting fish in early spring, it is almost certainly a Callery pear. NC State Extension writes that the flowers "emit an unpleasant odor, often described as rotting fish", attributed to chemicals the flowers release to attract pollinators. Bradford is the best-known cultivar, developed in the 1950s; other varieties include Chanticleer, Cleveland Select, Autumn Blaze and Aristocrat.

To confirm it, check the leaves: glossy and oval with serrated edges, turning red or purple in fall. The fruit is small and hard. NC State lists Callery pear's bloom as February to April in the Southeast, ahead of most native trees, which is why wild stands show up as white drifts along highways each spring. Once the original Bradford trees could cross-pollinate with newer varieties, they began setting fertile seed; birds spread it, and the wild offspring can carry thorns up to 4 inches long. Details, look-alikes and state sale bans are on the Bradford pear page.

Serviceberry, dogwood and cherries: the early-spring natives and ornamentals

Downy serviceberry. Look for drooping clusters of 6 to 14 star-shaped white flowers on a small tree with no leaves yet, or with leaves just unfolding. The NC State Plant Toolbox gives a bloom window of March to May, with flower clusters 3 to 7 inches long. Young leaves are covered with fine hairs underneath. Serviceberry grows wild from New Brunswick to Florida and west to Minnesota and Texas.

Flowering dogwood. What looks like four white petals is four bracts, each about 2 inches long and notched at the tip, around a small button of green true flowers, according to the NC State profile. It blooms before the leaves, from March to May. The leaves that follow are opposite, with veins that curve up toward the tip, and the tree carries clusters of glossy red fruit from August to October.

Yoshino cherry and other cherries. The Missouri Botanical Garden lists Yoshino cherry as blooming March to April, with fragrant white flowers, sometimes tinged pink, in clusters of 3 to 6 that open before or with the leaves. Small black cherries about half an inch across follow, and the leaves are toothed, elliptic to oval, up to 5 inches long. Wild black cherry blooms later, April to May in the Southeast, according to NC State. The cherry tree page covers how to tell cherries apart by bark and leaf.

Magnolias: early stars and summer giants

Star magnolia is a small tree, 15 to 20 feet tall, often grown as a large shrub, from Japan. The Missouri Botanical Garden's Plant Finder gives March as its bloom time, with fragrant, star-shaped white flowers in late winter to early spring, each with 12 to 18 narrow, strap-like tepals (petal-like parts). The Garden notes that frost damage to the flowers is a concern.

Southern magnolia blooms much later and is unmistakable. The NC State profile describes fragrant, creamy white flowers 8 to 12 inches across, opening from May to June, with sparse flowering through summer. The leaves are evergreen, leathery and glossy, 5 to 10 inches long, often with rusty-brown fuzz underneath. NC State gives its distribution as Maryland southwest to Texas and southeast to Florida.

Black locust and catalpa: late spring, with pods

Black locust blooms from April to June with fragrant, pea-like white flowers in hanging clusters 5 to 8 inches long. The NC State profile describes alternate, pinnately compound leaves with up to 23 leaflets and flat, purple-brown seed pods 2 to 4 inches long that can stay on the tree through winter. Native to the Appalachian and Ozark mountains, it has naturalized in all 48 contiguous states. For the locusts in more depth, see the locust page.

Northern catalpa is the late-spring answer to "white flowers and long seed pods". The Missouri Botanical Garden's Plant Finder entry lists a May to June bloom of bell-shaped, orchid-like white flowers up to 2 inches long, with purple and yellow spotting inside, in upright clusters. Slender green pods 12 to 22 inches long follow, ripen brown in fall and split lengthwise. Its broad leaves reach 12 inches and are rounded to heart-shaped at the base. For other heart-shaped leaves, see trees with heart-shaped leaves.

How to tell them apart in the field

1. Look closely at one flower. Four notched "petals" around a green button: dogwood. A star of 12 to 18 narrow tepals: star magnolia. Pea-shaped: black locust. Bell-shaped and spotted inside: catalpa. Wider than your hand: southern magnolia. Small, open flowers in clusters: pear, cherry, plum or serviceberry, so go on to steps 2 and 3.
2. Smell it. Fishy: Callery pear. Sweet and fragrant: black locust, star magnolia, southern magnolia, Yoshino cherry.
3. Check the leaves. None yet: star magnolia, dogwood, often serviceberry. Compound: black locust. Huge and evergreen: southern magnolia. Opposite: dogwood.
4. Note the month and your region. A white tree in February in Georgia and one in June in Illinois are not the same list.

A photo while it is in bloom

Flowers last only a week or two, so a photo taken now is worth more than a description later. Tree Identifier names a tree from one photo of the flowers, leaves or the whole crown; flowering dogwood, southern magnolia, black locust and Japanese flowering cherry are in its Collection, and it also names trees outside the Collection, such as Callery pear. Tree Identifier shows no confidence score, so check its answer against the petal count and leaves above. If you allow location, its Tree Map pins the find so you can come back in fall for the fruit and fall color.