The common name pale dogwood presumably refers to the underside of the leaves, which are evident here in both the curled leaves that have turned purplish-red and many of the fallen leaves in the water.
This photograph was taken in UBC Botanical Garden’s Carolinian Forest Garden in late October of 2017. I have my doubts that we will see such colour this autumn. Possibly due to the limited rainfall in the latter half of summer locally, many shrubs and small trees are barely producing anthocyanins. Instead, they are turning yellow or brown and crispy before falling, several weeks ahead of schedule.
Cornus obliqua is native to much of the eastern USA and Canada, although its range does not extend into the southeastern states of the USA. Reaching about 5m (~16 ft.) in height, this shrub species prefers “alluvial woods, river and stream banks, wet meadows, marshes, ditches”; as you may note, these plants are planted in an ideal location within UBC Botanical Garden.
Many references may place Cornus obliqua as a subspecies of Cornus amomum (and another), but the 2017 treatment of Cornus in the Flora of North America seems robust to me, so I’ve opted to follow their naming convention. Given that it was first published as a distinct species by the “softly blacklisted” Rafinesque, I wonder if there has been some longstanding bias (likely inadvertent in later works) against recognizing it as its own species.
Additional photographs are available from the Friends of the Wild Flower Garden, Cornus obliqua; the epithet is also explained on this page, “[it] means ‘lopsided’ or ‘oblique’ and refers to the drupe’s stone pit which is of a lopsided shape, narrowed and pointed at the base”.