Physiognomy and Structure: This alliance is dominated by low-growing forbs. Total vegetation cover ranges from low to high across sites but within a specific site cover can vary greatly during a single growing season if the site dries out and most hydrophytes die, exposing mudflats.

Floristics: Polygonum pensylvanicum is typically dominant but some stands contain the exotic Polygonum lapathifolium. Associates in Oklahoma include Ammannia coccinea, Helianthus annuus, Lemna minor, Spirodela polyrrhiza, Stuckenia pectinata (= Potamogeton pectinatus), Utricularia gibba (= Utricularia biflora), and Xanthium strumarium.

Dynamics:  Stands in this alliance are flooded for most or all of the growing season. Some stands dry out in the late summer most years and others only during multi-year droughts. When stands do dry out, some of the wetland plants may be killed, and the soil is exposed for colonization by upland plants. These drying phases add a degree of environmental diversity to the sites and affect the composition and vegetation cover of stands.