Populus trichocarpa

The Balsam poplars, which come from North America and Asia, draw their name from the sweet-smelling sticky gum or balsam that covers their bud scales. This becomes noticeable in spring, just as die leaves open, and often the fragrance fills the air and can be detected many yards away from the trees. The species illustrated here comes from Alaska and western British Columbia on the western seaboard of North America; there it is also called the Alaskan cottonwood, because of the downy white hairs on its seeds, which in the mass resemble cotton-wool. The eastern form, P. bahainifeta, ranges east to Labrador.

Most Balsam poplars are grown as ornamental trees, but there is a hybrid race that is recommended for timber production, particularly in the west of Britain, and qualifies for a planting grant (see page 53). This is Populus tacamahaca x trichocarpa '32' anditwas raised by crossing the Alaskan species with another Balsam poplar that grows farther south in British Columbia, Washington and Oregon.

Figure 67 shows the remarkably long female catkins, dark carpels and curiously lobed stigmas, that are typical of the Balsam group. The sticky, fragrant winter buds are dark in colour - blue-black rather than brown.

FIGURE 67

Winter twigs and buds of Western Balsam poplar, with long feathery female catkins opening in April (x|). The single female flower (X6) consists of a lobed green cup carrying a two-valved capsule which is topped by two curiously bi-lobed stigmas. (Basal bract is not shown).

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