Polygonaceae, the buckwheat, smartweed, or knotweed family.
Plant: Twining vine, to 4' long, with heart-shaped leaves, and small, elongated clusters of tiny greenish-white flowers. Annual
Flowers: Tiny, greenish-white, about 1/8" long, in spike-like racemes growing from the leaf axils. Mostly with 5 petal-like sepals, but they are difficult to count, and no petals.
Leaves: Technically alternate, but often in small, tight groups of 2 or 3 at nodes, along with flowering stalks, thus appearing whorled or opposite. Heart-shaped (cordate), to about 2.5", petioled, with a pointed tip and notched base.
Fruit: A triangular achene.
Habitat: Fields, waste places, roadsides.
Despite its common name, this Eurasian introduction, though superficially similar in habit to
the true bindweeds (Convolvulus), is a member of the buckwheat family, and is sometimes
known as Wild Buckwheat.
The most obvious differences are the small clustered flowers (as opposed to bindweed funnels)
and the characteristic buckwheat family leaf sheaths on the stems.
The seeds, like buckwheat, are edible, and the plant was cultivated in the past, but the
yield is too low to make a viable modern crop.
The plant is invasive in parts of North America, and sometimes a troublesome weed in
cultivated fields and gardens.
Classically placed in the extended genus Polygonum, the plant has recently been
placed in a separate small genus, Fallopia.
Where to find it:
Uncommon in the park. I have found a single example in the hedgerow on the east side of
the softball field.