There is no single exact number, because botanists disagree about where one birch species ends and the next begins. Flora of North America, a standard botanical reference, puts the birch genus (Betula) at about 35 species worldwide, with 18 of them in North America. On top of that come many cultivars and natural hybrids. For a home landscape, though, only a handful of birches matter.

Table of Contents

The short answer: Flora of North America counts about 35 birch species worldwide, 18 of them in North America. Birches hybridize freely, which is one reason counts vary between references. The ones most often planted in North America are river birch, paper birch, European white birch, gray birch, sweet birch and yellow birch.

Why the count varies

Flora of North America notes that birches hybridize freely, so specimens are often difficult to identify, and it calls the genus taxonomically difficult because of high variability and frequent hybridization. Some references split populations into more species, others lump them together. The same reference groups birches into three broad lines:

Large trees with dark or peeling bark, including yellow birch, sweet birch and river birch.
Small to medium trees with white bark that often peels in sheets, including paper birch and its European counterpart.
Dwarf shrubby birches of cold, northern regions.

Flora of North America describes birches as trees or shrubs of cool, moist places across the northern temperate, boreal and arctic zones, from stream banks and lakeshores to damp woods.

The birches you are most likely to meet

These are the species The Morton Arboretum profiles for home landscapes. Sizes are Morton’s mature ranges.

Birch	Mature height	Bark	Bronze birch borer (per Morton)
River birch (Betula nigra)	30 to 40 feet	Salmon-pink to reddish-brown, peeling	Resistant
Paper birch (B. papyrifera)	50 to 70 feet	White	Some resistance
European white birch (B. pendula)	40 to 50 feet	White	Very susceptible
Gray birch (B. populifolia)	20 to 40 feet	Chalky white on older trees, does not peel	Some resistance
Sweet birch (B. lenta)	40 to 50 feet	Shiny red-brown when young, darker and scaly later	Some resistance
Yellow birch (B. alleghaniensis)	60 to 75 feet	Silvery bronze, peeling in small strips	Some resistance

River birch

Morton calls river birch a popular, fast-growing native tree for the home landscape, with salmon-pink to reddish-brown bark that peels to reveal lighter inner bark. Morton lists wet soil among the conditions it accepts, and it is resistant to bronze birch borer, the insect that kills many stressed white-barked birches. Morton notes iron chlorosis (yellow leaves) is common in high-pH soils. See why river birch leaves turn yellow.

Paper birch

The classic white-barked native birch of the north. Morton says it has lovely white bark and yellow fall color but is not a good tree for tough sites, and shows some resistance to bronze birch borer. It prefers full sun, acid soil and moist, well-drained conditions.

European white birch

Also sold as silver birch. Morton says it is very susceptible to bronze birch borer and that this has limited its use in recent years, even though it was once planted widely. If you want white bark in a hot or dry area, a borer-resistant species or cultivar is a safer bet.

Gray birch

A narrow, pyramidal native of cool climates. Morton says older trees develop chalky white bark that does not peel, with black triangular patches under the branches, and calls it a good selection for poor soils. It lists gray birch at 20 to 40 feet with some resistance to bronze birch borer.

Sweet and yellow birch

Both are larger forest natives with darker or bronze bark. Flora of North America notes that some birch twigs have a wintergreen taste and odor, and Morton says crushed sweet birch stems smell like wintergreen. Morton lists yellow birch as one of the larger birches, up to 75 feet tall and wide.

How to tell them apart

Bark is the quickest clue, but young trees of several species look alike, and leaf shape, catkins and twig scent help. For a step-by-step guide, see how to identify birch tree species. If you are not sure whether you have a birch or an aspen, read the difference between birch and aspen.

Picking a birch for your yard

The Royal Horticultural Society notes that birches range from tall specimens that can eventually reach 40 feet or more down to compact forms for small spaces, and that hard pruning does not suit birches, so it is best to choose the right size from the start. A few practical rules from the profiles above:

Wet or heavy soil: river birch is the most tolerant.
Hot summers or a history of borers: favor river birch or a borer-resistant species over European white birch.
Cool, moist sites with acid soil: paper birch and yellow birch fit.
Small yards or poor soil: gray birch, which Morton recommends for poor soils, or a compact cultivar.

Whatever you choose, steady moisture and a cool, mulched root zone keep birches healthy. See how much water birch trees need and common birch diseases and pests.

Key takeaways

Flora of North America counts about 35 birch species worldwide, 18 in North America; counts vary because birches hybridize freely.
The common landscape birches are river, paper, European white, gray, sweet and yellow birch.
River birch is resistant to bronze birch borer; European white birch is very susceptible, according to The Morton Arboretum.
Choose a species that fits your site and space, since birches do not take hard pruning well.

Sources

Betula, Flora of North America
Paper Birch, The Morton Arboretum
River Birch, The Morton Arboretum
European White Birch, The Morton Arboretum
Gray Birch, The Morton Arboretum
Sweet Birch, The Morton Arboretum
Yellow Birch, The Morton Arboretum
How to grow birch, Royal Horticultural Society

Top photo: Cayambe, CC BY-SA 3.0, via Wikimedia Commons

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