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Ptilimnium capillaceum

(Michx.) Raf.

Mock Bishopweed

G5Secure Found in 2 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
UnknownThreat Impact
Identity
Unique IDELEMENT_GLOBAL.2.129035
Element CodePDAPI1Y010
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderApiales
FamilyApiaceae
GenusPtilimnium
Other Common Names
herbwilliam (EN)
Concept Reference
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-06-13
Change Date1988-08-04
Edition Date2025-06-13
Edition AuthorsN. Ventrella (2025)
Threat ImpactUnknown
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Number of Occurrences> 300
Rank Reasons
Ptilimnium capillaceum is an annual forb occurring in forest openings, pine savannas, bottomlands, swamps, brackish and freshwater marshes, pond- and lake- shores, ditches, pastures, and wet places of eastern North America and the West Indies in the Bahamas, Cuba, and Puerto Rico. In In North America, it is found from Massachusetts, New York, and Missouri south to Florida and Texas. There are over 1,000 occurrences rangewide, which are potentially threatened by development, water diversion, alteration of hydrology, erosion, succession, recreational activities, invasive species, and other threats in some places. Little is known about threats and trends, but with a large range extent, high number of occurrences, abundant habitat, broad habitat preferences, and no obvious intrinsic vulnerabilities, Ptilimnium capillaceum is considered secure.
Range Extent Comments
Ptilimnium capillaceum occurs in eastern North America and the West Indies in the Bahamas, Cuba, and Puerto Rico (FNA 2024). In North America, it is found from Massachusetts, New York, and Missouri south to Florida and Texas (Weakley and the Southeastern Flora Team 2025). Range extent was estimated to be over 2.7 million square kilometers using herbarium specimens, photo-based observations, and NatureServe Network occurrence data collected between 1994 and 2025 (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Occurrences Comments
By applying a 1 km separation distance to herbarium specimens, photo-based observations, and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are more than 1,000 occurrences rangewide (GBIF 2025, iNaturalist 2025, NatureServe 2025, RARECAT 2025, SEINet 2025).
Threat Impact Comments
Although threats are not widely documented, Ptilimnium capillaceum is likely threatened by development, water diversion, alteration of hydrology, erosion, succession, recreational activities, invasive species, and other threats in some places. However, they are considered negligible given the broad range and large number of occurrences of the species and its somewhat flexible and abundant habitat, as well as no obvious intrinsic vulnerabilities.
Ecology & Habitat

Habitat

Ptilimnium capillaceum occurs in "moist depressions in openings of mesic to dry forests or pine savannas and flatwoods, open bottomlands, swamps, seeps, brackish and freshwater marshes, shores of ponds and lakes, ditches, low pastures, fencerows, [and] other wet places" from 0-300 m in elevation (FNA 2024).

Ecology

Ptilimnium capillaceum produces flowers in May through August and fruits from July to September (FNA 2024).
Terrestrial Habitats
Forest/WoodlandForest - Conifer
Palustrine Habitats
HERBACEOUS WETLANDFORESTED WETLANDRiparian
Other Nations (1)
United StatesN5
ProvinceRankNative
KentuckyS1Yes
DelawareS4Yes
MississippiSNRYes
LouisianaSNRYes
New JerseyS4Yes
GeorgiaSNRYes
MissouriSHYes
District of ColumbiaSNRYes
MarylandSNRYes
PennsylvaniaSXYes
New YorkS3Yes
FloridaSNRYes
IllinoisSNRYes
ConnecticutSNRYes
MassachusettsSNRYes
ArkansasSNRYes
OklahomaSNRYes
TennesseeSNRYes
North CarolinaS5Yes
Rhode IslandS2Yes
South CarolinaS5Yes
VirginiaS5Yes
AlabamaSNRYes
TexasSNRYes
Threat Assessments
ThreatScopeSeverityTiming
Unknown/undetermined———

—

Plant Characteristics
DurationANNUAL
Economic Value (Genus)No
Roadless Areas (2)
North Carolina (1)
AreaForestAcres
Pond Pine BCroatan National Forest2,961
Texas (1)
AreaForestAcres
Winters BayouNational Forests in Texas730
References (8)
  1. Flora of North America Editorial Committee (FNA). 2024. Flora of North America north of Mexico. Vol. 13. Magnoliophyta: Geraniaceae to Apiaceae. Oxford Univ. Press, New York. xxiv + 566 pp.
  2. Global Biodiversity Information Facility (GBIF). 2025. Global Biodiversity Information Facility (GBIF) data portal. Online. Available: https://www.gbif.org/ (accessed 2025).
  3. iNaturalist. 2025. Online. Available: https://www.inaturalist.org (accessed 2025).
  4. Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
  5. NatureServe. 2025. NatureServe Network Biodiversity Location Data. NatureServe, Arlington, Virginia.
  6. <p>NatureServe's Rapid Analysis of Rarity and Endangerment Conservation Assessment Tool (RARECAT). 2025. Version: 2.1.1 (released April 04, 2025).</p>
  7. Southwest Environmental Information Network (SEINet). 2025. Collections Databases. Online. Available: https://swbiodiversity.org/seinet/collections/index.php (accessed 2025).
  8. Weakley, A.S., and Southeastern Flora Team. 2025. Flora of the southeastern United States Web App. Edition of February 18, 2025. University of North Carolina Herbarium (NCU), North Carolina Botanical Garden, University of North Carolina, Chapel Hill. Online. Available: https://fsus.ncbg.unc.edu (accessed 2025).