Betula (Betulaceae)

Betula occidentalis female catkins
Tree Book, British Columbia

Betula nigra

Betula nigra

Trees and shrubs with round (2-5 cm) toothed leaves, generally smooth bark. Reproduction by papery female and male catkins, seeds winged 2 mm. Temperate to alpine, Northern Hemisphere.

Pollen light micrograph:
Pollen grains spherical - triangular 30 - 35 µm. Pores with chamber separating inner and outer walls (vestibulum).

Pollen scanning electron micrograph (SEM)
Surface scabrate to rugulate (consisting of linear elements).

Production and Dispersal:
Prolific producer with good dispersal.

Pollen well pererved.

Fossil Occurrence:
Cretaceous (Cenomanian Betula ajatensis Bolk.) becoming common in the Miocene (20 My)

    Takeoka, M.,1963.
    On the fine structure of the pollen walls in some Scandinavian Betulaceae. Grana Palynologica 4: 161-188

    Birks, H.J.B.,1968.
    The identification of Betula nana pollen New Phytol. 67: 309-314

    Ives, J.W.,1977.
    Pollen separation of three North America birches. Arctic Alpine Res. 9: 73-80

    Leopold, E.B.,1956.
    Pollen size-frequency in New England species of the Genus Betula Grana Palynologica 1: 140-147.

    Nair, P.K.K.,1961.
    Pollen grains of Indian Plants 1. Bull National Botanic Gardens (India) 53.


Owen K. Davis 01/00