Ruellia strepens
Smooth ruellia
Image of Ruellia strepens

Photo by Bradford S. Slaughter 

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Key Characteristics

Forb to 1 m tall of floodplain forests; stem mostly hairless, bearing opposite, ovate leaves on short petioles; flowers tubular and blue to violet in color.

Status and Rank

  • State Status: E
  • State Rank: S1
  • Global Rank: G4G5


County NameNumber of OccurrencesYear Last Observed
Distribution map for Ruellia strepens

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Smooth ruellia is known only from a few sites in rich lowland woods in Lenawee County. The species is more widespread and common south of Michigan in Ohio, where it occurs in riparian forests, thickets, and streambanks. In the Chicago region, this species is known from shaded floodplains in the Kankakee River valley.

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Associated Plants

Trees: Acer saccharinum (silver maple), Carya laciniosa (shellbark hickory), Celtis occidentalis (hackberry), Fraxinus pennsylvanica (green ash), Juglans nigra (black walnut), Platanus occidentalis (sycamore), Ulmus americana (American elm).

Shrubs and Vines: Cephalanthus occidentalis (buttonbush), Toxicodendron radicans (poison-ivy), Vitis riparia (riverbank grape).

Herbs: Ambrosia trifida (giant ragweed), Arisaema dracontium (green dragon), Asclepias incarnata (swamp milkweed), Carex davisii, C. grayi, C. lupulina, C. muskingumensis, C. stipata, C. tribuloides, Elymus virginicus (Virginia wild-rye), Iris virginica (southern blue flag), Laportea canadensis (wood nettle), Leersia oryzoides (cut grass), Persicaria lapathifolia (nodding smartweed), Rumex verticillatus (water dock), Saururus cernuus (lizard's-tail), Symphyotrichum ontarionis (Lake Ontario aster), Teucrium canadense (wood-sage), Viola sororia (common blue violet).


The species likely requires periodic disturbance of the forested canopy, as flowering plants are usually found in partial light in openings and at forest margins.

General Survey Guidelines

Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgment of the investigator.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at [Accessed Sep 24, 2018]


Survey References

Technical References

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