PlantWatch

Aspen Poplar (Populus tremuloides)

Photo by Elisabeth Beaubien

Also known as: trembling aspen
French name: tremble
Bloom time: March to May
Report for: YK, NT, BC, AB, SK, MB, ON, QC, NB, NS, PEI, NF

General: Deciduous tree, up to 30 m tall. Trunk is smooth with light green or pale bark. Large trees can have black cracks in the bark at the base. Poplar trees are either male or female — only male trees are observed for PlantWatch.

Leaves & Twigs: Leaves are small (3-7 cm long), light to medium green in colour, and round-shaped with a small, sharp tip.

Flowers & Fruit: Flowers are found in catkins, which look like soft caterpillars hanging from twigs; blooming is completed before leaves emerge.
Male flowers: Fuzzy catkins emerge in late winter, and lengthen in early spring to reveal red/pink pollen sacs. These release pollen into the air, and the catkin eventually dries up and falls off.
Female flowers: Catkins turn green and capsules form, to later release fluffy, white seeds.

Habitat: Aspen is common in both dry and moist woods, but cannot tolerate shade.

Sampling: Tag a male tree for observation (see catkin description)

To Observe:

• First bloom: When the catkins on the male tree first start shedding pollen (3-places)
• Mid bloom: When 50% of the male catkins have lengthened and shed pollen
• Leafing: When the first leaves have emerged and unfolded completely (three places)