Midwestern Purple Bluets

Houstonia purpurea var. calycosa Gray

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Dicotyledoneae (Dicots)
Rubiaceae (Madder Family)
State Protection
Listed as Endangered by New York State: in imminent danger of extirpation in New York. For animals, taking, importation, transportation, or possession is prohibited, except under license or permit. For plants, removal or damage without the consent of the landowner is prohibited.
Federal Protection
Not Listed
State Conservation Status Rank
Historical (Possibly extirpated) in New York - Missing from New York; known only from historical records (more than 30 years ago), but still some possibility of rediscovery upon further searching.
Global Conservation Status Rank
Secure globally - Both the species as a whole and the subspecies/variety are common in the world; widespread and abundant (but may be rare in some parts of its range).


State Ranking Justification

There are no verified occurrences, 3 historical occurrences.

Conservation and Management



This taxon has not been observed in New York since the 1940's. The sparse habitat information we have from historical records indicate meadows, and sandy old fields (New York Natural Heritage Program 2011). Dry woods, pine-barrens, prairies and bottomlands (Gleason and Cronquist 1991). Dry open woods, slopes and pastures (Fernald 1970).

Associated Ecological Communities

  • Mowed roadside/pathway*
    A narrow strip of mowed vegetation along the side of a road, or a mowed pathway through taller vegetation (e.g., meadows, old fields, woodlands, forests), or along utility right-of-way corridors (e.g., power lines, telephone lines, gas pipelines). The vegetation in these mowed strips and paths may be dominated by grasses, sedges, and rushes; or it may be dominated by forbs, vines, and low shrubs that can tolerate infrequent mowing.
  • Pastureland*
    Agricultural land permanently maintained (or recently abandoned) as a pasture area for livestock.
  • Red cedar rocky summit* (guide)
    A community that occurs on warm, dry, rocky ridgetops and summits where the bedrock is calcareous (such as limestone or dolomite, but also marble, amphibolite, and calcsilicate rock), and the soils are more or less calcareous. The vegetation may be sparse or patchy, with numerous lichen covered rock outcrops.
  • Rocky summit grassland* (guide)
    A grassland community that occurs on rocky summits and exposed rocky slopes of hills. Woody plants are sparse and may be scattered near the margin of the community. Small trees and shrubs may be present at low percent cover.
  • Successional northern sandplain grassland* (guide)
    A meadow community that occurs on open sandplains that have been cleared and plowed (for farming or development), and then abandoned. This community is usually dominated by low, dry turf of sedges and grasses less than 30 cm (12 inches) tall, and include patches of open sand and patches of soil covered with mosses and lichens.

* probable association but not confirmed.


New York State Distribution

Widely scattered.

Identification Comments

Identifying Characteristics

Distinguishing characteristics: leaves oblong-lanceolate, 5-10 mm wide; sepals 3-6.5 mm long at anthesis. Best life stage for ID: in flower or fruit. Characteristics needed to ID: stem with leaves and an intact calyx.

Similar Species

Houstonia purpurea var. purpurea has ovate to lance-ovate leaves, 10 mm wide; sepals at anthesis 1.7-4.5 mm long. It may be better to lump these two varieties since the leaf characteristics vary widely.

Best Time to See

Houstonia is most likely to be found when in flower from June to early August.

  • Flowering
  • Fruiting

The time of year you would expect to find Midwestern Purple Bluets flowering and fruiting in New York.


Midwestern Purple Bluets
Houstonia purpurea var. calycosa Gray

  • Kingdom Plantae
    • Phylum Anthophyta
      • Class Dicotyledoneae (Dicots)
        • Order Rubiales
          • Family Rubiaceae (Madder Family)

Additional Common Names

  • Purple Bluets
  • Southern Bluets


  • Hedyotis lanceolata Poir.
  • Hedyotis purpurea var. calycosa (Gray) Fosberg
  • Houstonia lanceolata (Poiret) Britton

Additional Resources


Fernald, M.L. 1950. Gray's manual of botany. 8th edition. D. Van Nostrand, New York. 1632 pp.

Gleason, Henry A. 1952. The New Britton and Brown Illustrated Flora of the Northeastern United States and Canada.

Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.

Holmgren, Noel. 1998. The Illustrated Companion to Gleason and Cronquist's Manual. Illustrations of the Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York.

Mitchell, Richard S. and Gordon C. Tucker. 1997. Revised Checklist of New York State Plants. Contributions to a Flora of New York State. Checklist IV. Bulletin No. 490. New York State Museum. Albany, NY. 400 pp.

New York Natural Heritage Program. 2010. Biotics database. New York Natural Heritage Program. New York State Department of Environmental Conservation. Albany, NY.

New York Natural Heritage Program. 2024. New York Natural Heritage Program Databases. Albany, NY.

Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.

Weldy, T. and D. Werier. 2010. New York flora atlas. [S.M. Landry, K.N. Campbell, and L.D. Mabe (original application development), Florida Center for Community Design and Research http://www.fccdr.usf.edu/. University of South Florida http://www.usf.edu/]. New York Flora Association http://newyork.plantatlas.usf.edu/, Albany, New York


About This Guide

Information for this guide was last updated on: August 10, 2011

Please cite this page as:
New York Natural Heritage Program. 2024. Online Conservation Guide for Houstonia purpurea var. calycosa. Available from: https://guides.nynhp.org/southern-bluets/. Accessed February 26, 2024.