Wild buckwheat loves to climb up neighboring plants. Its viney growth habit allows it to capture more light easily, at the expense of its neighbor. This is a good competitive trait to have, don't you think? Climbing below on quackgrass plants in soybeans (left), wild carrot (center), and on corn (right).
Seedling leaf shapes (below).
Leaf shapes below (left); on the right, at the bottom is wild buckwheat leaf shapes, on the top part of the right picture are some bindweed leaf shapes for comparison. Although the bindweeds and wild buckwheat are different species, they both are viney and at first glance seem very similar. This is a good example of convergent evolution, two different species adapting the same trait.
Wild buckwheat leaves, stems and seeds (below). Notice the ochrea at the junction of the stem, leaf and seed (below, right). This ochrea is the same as on the other Polygonum spp. like the knotweeds and the smartweeds.
Seedheads showing the triangular seeds (below, left and center). The seedheads flowering on the whole plant (below, right).
The wild buckwheat plants below are spreading across the ground because they have no neighbors to climb up on. No need to be tall if there is no neighbors shading you and competing for light.