The Endangered Species Garden established in 1994 with support from Star Enterprises displays rare native plants for the public to view year-round. Plants germinated in our greenhouses are used for display in our Endangered Species Garden and Mercer's Plaza and displays for off-site conservation programs given by Mercer.

Germination and growth to maturity studies at Mercer Arboretum and Botanic Gardens in 1988-89 revealed non-specific soil requirements and ease of cultivation. Seedlings, however, do not tolerate extended periods of submerging. Public educational display plants for the Endangered Species Garden at Mercer are germinated within our greenhouses.In Spring 2002, the River Oaks Garden Club of Houston, TX provided a generous gift to begin the expansion and renovation of Mercers Endangered Species Garden. Plants produced for educational display gardens or for specific restoration and reintroduction projects are produced within Mercers nursery greenhouses and within our Conservation Area. The Conservation Area provides secure, raised beds for mass propagation of plants/seeds. Each bed is provided with independently controlled irrigation and substrates that meet the unique requirements for each species. Seeds from several sites within Harris County collected by Dr. Larry Brown of Houston Community College and Ralph Taylor of the Harris County Flood Control District are stored at Mercer Arboretum and Botanic Gardens. Banked wild-collected seed date to 1988. Mercer also banks subsets of rare seeds collected from field surveys and from propagation work with our collaborating CPC institution, the Lady Bird Johnson Wildflower Center, Austin, TX and the National Center for Genetic Resources Preservation (NCGRP) in Ft. Collins, CO (formerly called the National Seed Storage Laboratories. Seeds from an in-house propagation of 1993 that had been in storage in Mercer's seed bank freezer germinated under greenhouse conditions at ~70% with ~50% survivorship during the Winter of 2001. Plants germinated in our greenhouses are used for display in our Endangered Species Garden and Mercer's Plaza and displays for off-site conservation programs given by Mercer. http://www.cp4.hctx.net/mercer/mplant.htm. This article appeared in Harris County Precinct 4 magazine, Parkscape, Autumn 2001 and reached 33,000 possible readers. Harris County Precinct 4 magazine, Parkscape publishes public information articles about the plant conservation efforts of Mercer Arboretum and Botanic Gardens. 115,000 issues are circulated annually of this quarterly publication. Articles about rare plants maintained at Mercer may be viewed at: http://www.cp4.hctx.net/mercer/mplant.htm.

Genetic studies completed by L. Brown and J.L. Strother (1988) documented disploidy, 2N= 16 and 6 in Hymenoxys texana.

Mercer Botanic Gardens maintains the Harris County Precinct 4 Prairie Dawn Preserve.  This is four acre preserve which shelters four naturally-occurring rare prairie species which includes Hymenoxys texana.  The floods of April and May of 2016 and Hurricane Harvey of 2017 have affected the drainage patterns causing erosion issues on this preserve.  Surveys conducted in April 2018 show that ~1000 more Hymenoxys texana (Texas prairie dawn plants) than the ~60 counted before Hurricane Harvey struck in 2017.  More than 10,000 were counted in 2016 before the floods of April and May 2016.  It is the belief of the Mercer Botanic Gardens that Hymenoxys texana is rebounding.  (Tiller et al. 2018)

Endemic to?saline prairies with cryptogamic soils within the Houston Coastal Prairie. Although nearly 60 sites are known for this species, almost all are threatened by development from the expanding city of Houston. Many of the sites are within 1 km of each other and probably form a single population. Some sites have been destroyed within a year of their discovery due to development.

Competition from woody vegetation heavy grazing by cattle and primarily, urban development (road construction and residential development) of the Coastal Prairies, especially within the Houston city limits where these plants are found.

Since 1986, populations found in Harris and Fort Bend Counties may total ~ 50 sites comprising an unknown number of individuals (Stark 1996).

Genetic studies completed by L. Brown and J.L. Strother (1988) documented disploidy, 2N= 16 and 6 in Hymenoxys texana. Germination and growth to maturity studies at Mercer Arboretum and Botanic Gardens in 1988-89 revealed non-specific soil requirements and ease of cultivation. Seedlings, however, do not tolerate extended periods of submerging. Public educational display plants for the Endangered Species Garden at Mercer are germinated within our greenhouses. The Endangered Species Garden established in 1994 with support from Star Enterprises displays rare native plants for the public to view year-round. In Spring 2002, the River Oaks Garden Club of Houston, TX provided a generous gift to begin the expansion and renovation of Mercers Endangered Species Garden. Plants produced for educational display gardens or for specific restoration and reintroduction projects are produced within Mercers nursery greenhouses and within our Conservation Area. The Conservation Area provides secure, raised beds for mass propagation of plants/seeds. Each bed is provided with independently controlled irrigation and substrates that meet the unique requirements for each species. Seeds from several sites within Harris County collected by Dr. Larry Brown of Houston Community College and Ralph Taylor of the Harris County Flood Control District are stored at Mercer Arboretum and Botanic Gardens. Banked wild-collected seed date to 1988. Mercer also banks subsets of rare seeds collected from field surveys and from propagation work with our collaborating CPC institution, the Lady Bird Johnson Wildflower Center, Austin, TX and the National Center for Genetic Resources Preservation (NCGRP) in Ft. Collins, CO (formerly called the National Seed Storage Laboratories. Seeds from an in-house propagation of 1993 that had been in storage in Mercer's seed bank freezer germinated under greenhouse conditions at ~70% with ~50% survivorship during the Winter of 2001. Plants germinated in our greenhouses are used for display in our Endangered Species Garden and Mercer's Plaza and displays for off-site conservation programs given by Mercer. http://www.cp4.hctx.net/mercer/mplant.htm. This article appeared in Harris County Precinct 4 magazine, Parkscape, Autumn 2001 and reached 33,000 possible readers. Harris County Precinct 4 magazine, Parkscape publishes public information articles about the plant conservation efforts of Mercer Arboretum and Botanic Gardens. 115,000 issues are circulated annually of this quarterly publication. Articles about rare plants maintained at Mercer may be viewed at: http://www.cp4.hctx.net/mercer/mplant.htm.

Semi-protected on 2 sites with a good possibility for management. Current management includes monitoring and seasonal mowing/burning of sites where possible.

Further develop protected sanctuaries within Harris and Ft. Bend Counties.

Expand seed bank. Propagation of seed for reintroduction efforts.