Common (Translated Scientific) Name: Late-flowering Thoroughwort - Wingstem Depositional Bar Alliance

Colloquial Name: Tall Forb Depositional Bar

Hierarchy Level:  Alliance

Type Concept: This alliance consists of vegetation of active shorelines and depositional bars of streams and rivers in the Central Appalachians and Interior Low Plateau. Examples occur on sandy riverbanks and depositional bars, as well as in sand deposits on bedrock floodplains and boulder bars. The vegetation is maintained by periodic flooding, and flood dynamics vary from low to high rates of sediment erosion and turnover. These habitats experience high rates of sediment erosion and turnover during even moderate floods and are inundated for 3-12% of the year, but are generally exposed for most of the growing season. Vegetation may be sparse during years of more continuous high water during the growing season. In normal growing seasons, the vegetation is a dense growth of tall (1-2 m), fast-growing annual and perennial forbs. There may be some spatial separation within stands between perennial forbs, found on more stable shores and bars, and weedy annuals, found on high-gradient reaches that experience high rates of sediment erosion and turnover. Examples may have a very high cover of weedy and invasive species. Some typical components include Amaranthus spinosus, Artemisia annua, Datura stramonium, Eupatorium serotinum, Polygonum lapathifolium, Polygonum pensylvanicum, Polygonum punctatum, Teucrium canadense, Verbesina alternifolia, and Verbena urticifolia, which are relatively constant and generally contribute most of the cover. Additional, less constant or abundant species include Polygonum cespitosum var. longisetum, Conoclinium coelestinum, Perilla frutescens, Dysphania ambrosioides, Mollugo verticillata, Solanum ptycanthum, Verbena hastata, Urtica dioica ssp. dioica, Solanum carolinense, and Hibiscus laevis. Herbaceous vines may also be numerous, with Calystegia sepium, Cynanchum laeve, and Cuscuta gronovii most frequent. Scattered individuals of shrubby to full-sized flood-tolerant trees (e.g., Platanus occidentalis, Acer saccharinum), as well as saplings of Betula nigra may be present.

Diagnostic Characteristics: This alliance is characterized by dynamic and variable species composition characterized by the presence of Eupatorium serotinum, Verbesina alternifolia, Teucrium canadense, or Conoclinium coelestinum occurring on alluvial depositional bars.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This alliance and its associations are intentionally described as floristically broad units, since colonization of this dynamic environment is often opportunistic, and species composition varies accordingly. Perennial forbs and grasses tend to dominate on more stable banks and bars, and annual species dominate on higher gradient shores with high rates of sediment erosion and turnover. Annual forbs and weedy invasive exotics can be a common component even in areas dominated by perennial forbs. Because of the stochastic and dynamic environment, species composition can be variable among occurrences. Some of the associations in this alliance have many weedy exotics in their occurrences, and further study is needed to determine whether this vegetation should be considered a natural or modified type.

Similar NVC Types: No Data Available

note: No Data Available