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Dicotyledoneae (Dicots)
Rubiaceae (Madder Family)
State Protection
Federal Protection
Not Listed
State Conservation Status Rank
Global Conservation Status Rank


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*
  • Pastureland*
  • Red cedar rocky summit* (guide)
  • Rocky summit grassland* (guide)
  • Successional northern sandplain grassland*


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 Southern Bluets flowering and fruiting in New York.


Southern Bluets
Houstonia purpurea var. calycosa Gray

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

Additional Common Names

  • Purple Bluets


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

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. 2019. 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 University of South Florida]. New York Flora Association, 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. 2019. Online Conservation Guide for Houstonia purpurea var. calycosa. Available from: Accessed March 25, 2019.

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