Some species are viney. The leaves are usually simple and alternate.
Flowers can be either perfect or imperfect.
They can also be found in cultivated fields, thickets, swampy woods, clearings, wastelands, along roadsides, in prairies, and on rocky, dry or cool and damp slopes. P. careyi is reported to occur on recent burns. Flowering dates for smartweed species vary. Most of the southern species flower in May and June, while their northern counterparts flower from July through November.