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Betula -
by Jingshuang Ma
Not peer reviewed
Last modified: 06/15/2006
Nomenclature
Betula L., Sp. Pl. 982. 1753. Gen. Pl. 422. 1754. LECTOTYPE: Betula alba L., designated by Britton & Brown (1913).
Chamaebetula Opiz, Lotos 5: 258. 1855. TYPE: Not designated.
Key to the species of Betula
1. Multi-stemmed shrub...Betula
pumila
1. Single- or multi-trunked tree...2
2. Bark on mature trunks whitish...3
2.
Bark on mature trunks yellowish-gray to dark reddish-brown or
blackish-brown...7
3. Bark on mature trunks tight, not exfoliating... Betula populifolia
3. Bark on mature trunks
exfoliating into thin strips...4
4. Leaf undersides pubescent at least along veins...5
4. Leaf undersides glabrous...6
5. Leaves cuneate or acute at the base... Betula papyrifera
5. Leaves subcordate at the
base...Betula cordifolia
6. Leaf apices with a long tapering tip...9
6. Leaf apices acuminate without long drawn tip...Betula
platyphylla
7. Leaf blades rhombic-ovate, base broadly cuneate to truncate;
twigs without a wintergreen taste or odor...Betula
nigra
7. Leaf blades ovate to elliptic, base rounded; twigs with a
wintergreen taste or odor...8.
8. Bark of mature trunks exfoliating; leaf undersides without
shiny resin dots...Betula alleghaniensis
8.
Bark of mature trunks not exfoliating; leaf undersides with shiny resin
dots...Betula lenta
9. Leaves deltate or rhombic, bases mostly cuneate; axillary
buds 4-5 mm long, apices acute or acuminate...Betula pendula
9. Leaves ovate,
bases mostly truncate; axillary buds 5-7 mm long, apices obtuse to
acute...Betula ×caerulea
List of Betula Species
- Betula ×caerulea (B. cordifolia × B. populifolia) - excluded species
- Betula alleghanensis
- Betula cordifolia - excluded species
- Betula lenta
- Betula nigra
- Betula papyrifera
- Betula pendula
- Betula platyphylla - excluded species
- Betula populifolia
- Betula pubescens - excluded species
- Betula pumila
