Highbush Cranberry

Viburnum opulus · also: guelder-rose, pimbina

How to ID it

Shrub with maple-like, three-lobed opposite leaves
Translucent red drupes in flat-topped clusters, each holding a single flat seed
Flat-topped spring flower clusters with showy sterile outer flowers
Cooked fruit gives off a distinctive musky, sweaty smell

⚠ Safety & lookalikes

Not a true cranberry — it's a Viburnum, so don't let the name suggest a Vaccinium.
Two forms look nearly identical: the edible native (var. americanum, formerly V. trilobum) is pleasantly tart, while European guelder-rose (V. opulus) is very bitter and can upset the stomach eaten raw or in quantity. Taste a single berry cautiously — sharply bitter means guelder-rose.
Always cook the fruit (jelly or sauce); don't eat raw berries in bulk, and don't eat the seed.

Harvest

Find these shrubs in damp thickets, woodland edges, and hedgerows; many ornamental plantings are the European guelder-rose. Wait until after the first frosts, when the translucent red drupes have hung in their flat clusters and softened. Pick whole clusters. Taste one raw, warily: acceptable-tart means the edible American form, mouth-puckering bitterness means the European type — cook only, and sparingly.

Prep

Always cook. Simmer the fruit, then press through a sieve to remove the single flat seed and skins. High pectin makes it set into a tart, ruby jelly that pairs with meat like real cranberry sauce. Expect a musky, sweaty odour while it cooks — it fades, and the finished jelly tastes bright.

Notes

One flat seed per berry marks a Viburnum, not a true cranberry. The maple-shaped opposite leaves and flat flower heads are your year-round ID.