Eastern shade-tolerant conifers

Picea mariana (Mill.) B.S.P. - black spruce

Image 1. Upper crown of a vigorously growing sapling showing the branching pattern and fully grown seed cones, mostly on (now) 2-season-old shoots of first-order branches, September: note the sylleptic shoots along the leader.

Image 2.Trees about 80 years old, showing typical narrow crowns with dense, tufts of branches and cones near their tops, September.

Image 3. Trees about 90 years old, September.

Image 4. Inside a 90-year-old stand, showing that many dead branches are retained along the main stems below the live parts of the crowns, September.

Image 5. Picea mariana growing in a mat-like manner in a bog at relatively high and exposed elevation, along with Larix laricina, August.

Image 6. A 2-season-old portion of a lateral branch, showing the typical arrangement of leaves along the shoots: note how a group of leaves hides the terminal bud when viewed from the side, September; terminal buds of all spruces have leaves around their bases that separate them from the nearest (distal) lateral buds.

Image 7. A terminal pollen-cone bud close to the bursting stage, late May or early June.

Image 8. A pollen cone shortly after its emergence from a distal lateral bud, late May or early June: the individual microsporophylls are evident.

Image 9. Pollen cones at the pollen-shedding stage, early June: note their erect orientation. The elongated structure at the left is an insect-caused gall growing from a distal lateral bud.

Image 10. A full-grown, terminally located pollen cone shortly after pollen has been shed, early June: note the extended axis at the base of the cone that carries the pollen-bearing part of the cone clear of the bud scales, and the more-distal axis extension that has separated the microsporophylls.

Image 11. Distal-lateral pollen cones after pollen shedding, and a new terminal shoot extending from its bud, mid-June.

Image 12. An erect, receptive seed cone in a distal lateral position, early June.

Image 13. Receptive seed cones in lateral positions along distally situated first-order, 1-year-old shoots, early June: note that vegetative buds are swollen but not yet burst.

Image 14. Erect, receptive seed cones in early June showing how the tips of the ovuliferous scales (cone scales) are reflexed and serve to direct pollen into the interior of the cone: small bracts subtending cone scales are visible.

Image 15. Seed cones with scale tips appressed to close the cone, and beginning to become pendent, mid-June, as vegetative buds burst.

Image 16. Pendent, almost full-grown seed cones in late June when elongation is also almost complete on shoots close by.

Image 17. Seed cones in a slightly earlier stage of development than that shown in No. 16 (shoot elongation is less advanced) showing how considerable parts of the bases of many cones are involved in the mechanism of movement of the cone from its erect state at receptivity to its later pendent state: this provides the bent cone base typical of many cones of Picea mariana(see No. 78).

Image 18. Full-grown seed cones, and nearer the base, "open" cones from two years previous, mid-July.

Image 19. Mature seed cones clusterd at the top of the crown of a bog-grown tree, September.

Image 20. An "open" seed cone, in June following maturation: many cones of Picea mariana open only slightly, if at all, in their first winter, and opening progresses over many subsequent years.

Image 21. Fire-killed Picea mariana with many seed cones evident: such cones provide a post-fire source of seed.

Image 22. A fire-killed stand of Picea mariana, with tufts in some crowns where cones provide seeds.

Image 23. A portion of the crown of a fire-killed Picea mariana with open seed cones.

Image 24. Seeds of Picea mariana: those at the right have had seed wings removed, and those at the left show upper and lower surfaces to display how the wing base covers one side of the seed and clasps two edges of the seed on the other side; the fine markings on the scale bar indicate millimetres.

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