Eastern shade-tolerant (one intermediate) broad-leaved species

Betula alleghaniensis Britton - yellow birch

Image 1. Overwintering twig with four male aments (male aments are borne in groups of 3 to 6 near the ends of long shoots).

Image 2. Male aments extended and pendent, with their flowers visible in the axils of their subtending bracts in the pollen-shedding stage, in mid-May, at the end of a long shoot of the previous year, and short shoots emerging from overwintered lateral buds further back down the long shoot: each of the latter bears two expanding preformed leaves, and two of them also bear a terminal female ament extended into its erect, position with its flowers in axils of bracts receptive to pollen.

Image 3. Erect female aments in mid-May, with their flowers evident in axils of bracts, borne on short shoots that also carry two expanding preformed leaves: remains of the bases of male aments shed from positions near the end of the supporting long shoot are also evident.

Image 4. Female aments enlarging following blooming of their flowers, late May.

Image 5. Female ament, remaining erect, with its bracts enlarged and assuming their typical three-lobed shape, late June: the leaves of the supporting short shoot have reached full size.

Image 6. Full-sized female aments beginning to show signs of drying of their bracts in late August.

Image 7. Preformed leaves of a new long shoot expanding at its base as the axis extends and neoformed stipulate leaves form and begin to grow out beyond them, late May.

Image 8. New male aments forming, in late August, at the end and in axils of neoformed leaves near the end of a long shoot.

Image 9. First-year seedlings (September) growing on an old Tsuga canadensis (L.) Carr. log under a high forest canopy: note the two oval cotyledons and the one or two neoformed leaves produced by the seedlings.

Image 10. First-year seedlings, in late June, shortly after germination in mineral soil exposed during logging operations the previous summer: the first neoformed leaves are expanding above the two oval cotyledons of some of the germinants (see also No. 11).

Image 11. First-year seedlings in late June as in No. 10 showing the extended hypocotyls below the cotyledons.

Information provided by:
Dr. G.R. Powell
Faculty of Forestry and Environmental Management at UNB