CPC Plant Profile: Texas Snowbell
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Plant Profile

Texas Snowbell (Styrax platanifolius ssp. texanus)

This shot shows the flowering plant with its glossy leaves. Photo Credit: San Antonio Botanical Garden
Description
  • Global Rank: T1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Styracaceae
  • State: TX
  • Nature Serve ID: 152043
  • Date Inducted in National Collection: 04/04/1991

Nestling its roots deep into the limestone cliffs of the Edwards Plateau, the Texas Snowbells (Styrax texana) dangles its delicate white flowers over the crystal clear waters of a Hill Country stream below. This is a beautiful, 10-15 foot tall deciduous shrub with heart-shaped leaves, which are green on top and silky white below. Each flower sets fruit, which contain the seeds for future generations of this species. The problem lies in the location of mature trees: most seeds ripen and fall into the stream below and are carried away. Some seedlings do survive but are quickly eaten by deer, wild goats, sheep or rodents. Presently, most wild populations consist of only mature trees. (Cox 2000).

Participating Institutions
CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.
Updates
Center for Plant Conservation
  • 12/03/2021
  • Reintroduction

My [Lois Sturm, Selah Bamberger Ranch Preserve] interest in the Texas Snowbell began in 1994. At the time, I was volunteering at Dolan Falls for The Nature Conservancy. They had recently acquired the ranch on the Devils River in Val Verde County of Texas. Biologists had discovered a large colony of mature plants along the river. This was the largest colony known at the time. Seeing the beautiful bloom and hearing about the snowbell’s endangered status motivated me to action.
After seven years of making landowner contacts, we were making new discoveries and collecting seeds from which we grew plants. The first introduction was in 2003. We have continued planting every year since then and now have 682 plants alive and well in the Nueces and Devils River watershed. Fortunately for us, the area where we planted had adequate rainfall except for 2008. Every plant was protected with a sturdy corral 6 foot in diameter. Each corral is strong enough to keep out cattle, deer and wild hogs and large enough to allow for some future regeneration. In 2008, one of our 2004 introductions produced viable seeds.
Most of our plants are in semi-shade conditions. Historically, there has been no care other than some weeding when taking annual growth measurements. We use weed barrier and “pasta” (cut grass) to slow down moisture loss. Each corral has three plants and an aluminum tag with a number. Records are kept regarding seed collection and grown plants are planted in the watershed from which the seeds were collected.
The germination rate on snowbell seeds is very high. After 60 to 90 days in stratification, we place the seed in a four inch container and within 60 days step the plant up to a one gallon container. It takes two years in the one gallon container to develop a good root system. We have planted them after one year, but with less success.
In 2008 all the ranches we planted on suffered a fifty year drought and record heat. We lost over 50% of the plantings made in October, November and December of 2007. (These have been replaced.) But of great interest is that of over 500 plants that had been planted one year or more, 99% not only survived the drought but also added growth.
Steven Fulton, our ranch biologist, is doing graduate studies on the snowbell to learn what pollinates it, what eats it and what disperses the seed. His findings will be published in 2011.

Center for Plant Conservation
  • 12/03/2021
  • Propagation Research

My [Lois Sturm, Selah Bamberger Ranch Preserve] interest in the Texas Snowbell began in 1994. At the time, I was volunteering at Dolan Falls for The Nature Conservancy. They had recently acquired the ranch on the Devils River in Val Verde County of Texas. Biologists had discovered a large colony of mature plants along the river. This was the largest colony known at the time. Seeing the beautiful bloom and hearing about the snowbell’s endangered status motivated me to action.
After seven years of making landowner contacts, we were making new discoveries and collecting seeds from which we grew plants. The first introduction was in 2003. We have continued planting every year since then and now have 682 plants alive and well in the Nueces and Devils River watershed. Fortunately for us, the area where we planted had adequate rainfall except for 2008. Every plant was protected with a sturdy corral 6 foot in diameter. Each corral is strong enough to keep out cattle, deer and wild hogs and large enough to allow for some future regeneration. In 2008, one of our 2004 introductions produced viable seeds.
Most of our plants are in semi-shade conditions. Historically, there has been no care other than some weeding when taking annual growth measurements. We use weed barrier and “pasta” (cut grass) to slow down moisture loss. Each corral has three plants and an aluminum tag with a number. Records are kept regarding seed collection and grown plants are planted in the watershed from which the seeds were collected.
The germination rate on snowbell seeds is very high. After 60 to 90 days in stratification, we place the seed in a four inch container and within 60 days step the plant up to a one gallon container. It takes two years in the one gallon container to develop a good root system. We have planted them after one year, but with less success.
In 2008 all the ranches we planted on suffered a fifty year drought and record heat. We lost over 50% of the plantings made in October, November and December of 2007. (These have been replaced.) But of great interest is that of over 500 plants that had been planted one year or more, 99% not only survived the drought but also added growth.
Steven Fulton, our ranch biologist, is doing graduate studies on the snowbell to learn what pollinates it, what eats it and what disperses the seed. His findings will be published in 2011.

Center for Plant Conservation
  • 12/03/2021
  • Reintroduction

This project began with the collection of seeds from the two largest knoen populations of Texas snowbells. Seedlings from these seeds were pot grown to 5 to 8 inches high. Twenty-five seedlings were planted at one site and 24 at another. Material from a single source was used at each site. Record rainfall washed away the seedlings at the first site, which was replanted. Wire cages were placed around each seedling when planted. Only seven of the original forty-nine plants died. Two plants flowered for the first time five years after plating.

Center for Plant Conservation
  • 12/03/2021
  • Propagation Research

This project began with the collection of seeds from the two largest knoen populations of Texas snowbells. Seedlings from these seeds were pot grown to 5 to 8 inches high. Twenty-five seedlings were planted at one site and 24 at another. Material from a single source was used at each site. Record rainfall washed away the seedlings at the first site, which was replanted. Wire cages were placed around each seedling when planted. Only seven of the original forty-nine plants died. Two plants flowered for the first time five years after plating.

  • 10/09/2020
  • Reintroduction

Two re-introduction experiments are currently in progress. Plants were grown in greenhouses at the San Antonio Botanical Garden and planted in their historic range with cages to prevent mammal herbivory. (McDonald 1996)

  • 10/09/2020
  • Living Collection

The San Antonio Botanical Garden currently maintains Texas Snowbells in test plots. Plants were grown in greenhouses at the San Antonio Botanical Garden and planted in their historic range with cages to prevent mammal herbivory. (McDonald 1996)

  • 10/09/2020
  • Orthodox Seed Banking

The San Antonio Botanical Garden currently maintains Texas Snowbells in test plots. Seeds have been collected from the wild and sent to the National Seed Storage Lab for long term storage

  • 10/09/2020
  • Seed Collection

The San Antonio Botanical Garden currently maintains Texas Snowbells in test plots. Seeds have been collected from the wild and sent to the National Seed Storage Lab for long term storage.

Cindy Barrett
  • 01/01/2010

Browsing by domestic livestock, exotic game, and native wildlife. Seed and seedling predation. Flooding and erosion. (McDonald 1996)

Cindy Barrett
  • 01/01/2010

When this species was listed in 1984, only 39 plants were known in the Texas counties of Edwards and Real. As of 2002, Texas Parks and Wildlife reports 10 populations in Edwards, Real, and Val Verde counties in Texas. (Texas Parks and Wildlife 2002)

Cindy Barrett
  • 01/01/2010

Two re-introduction experiments are currently in progress. Plants were grown in greenhouses at the San Antonio Botanical Garden and planted in their historic range with cages to prevent mammal herbivory. (McDonald 1996)

Cindy Barrett
  • 01/01/2010

The San Antonio Botanical Garden currently maintains Texas Snowbells in test plots. Seeds have been collected from the wild and sent to the National Seed Storage Lab for long term storage.

Cindy Barrett
  • 01/01/2010

Monitor re-introduction sites. Landowners have shown an interest in new re-introduction studies.

Cindy Barrett
  • 01/01/2010

Collect seed from the various populations for storage at the National Seed Storage Lab. Germination and growth studies.

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Photos
Nomenclature
Taxon Styrax platanifolius ssp. texanus
Authority (Cory) P.W. Fritsch
Family Styracaceae
CPC Number 4162
ITIS 566099
USDA STPLT
Common Names Texas snowbells
Associated Scientific Names Styrax texanus | Styrax platanifolius ssp. texanus | Styrax texana | Styrax platanifolius var. texanus
Distribution Edwards Plateau area of Texas (Edwards, Real, and Val Verde counties)
State Rank
State State Rank
Texas S1
Habitat

Currently found on steep limestone cliffs or bluffs above stream channels in juniper-oak savannas on the Edwards Plateau as well as in creosote bush shrub habitat in the eastern Trans-Pecos basins. (USFWS 1984) Associates often include the Texas ash, sycamore, little walnut, Mexican silktassel, Lacey oak, Texas oak, Mexican buckeye, Texas mountain laurel, Texas persimmon, guajillo, and Ashe juniper. (Texas Parks and Wildlife 2002)

Ecological Relationships

A highly palatable species, the browsing of deer, goats and exotic ungulates are a serious threat to the survival of Texas snowbells.

Pollinators
Common Name Name in Text Association Type Source InteractionID
Other
Insects Suspected Pollinator Floral Link
Reintroduction
Lead Institution State Reintroduction Type Year of First Outplanting
Texas
Texas
Texas
Texas
Texas
Texas
Texas
Texas
Texas
Texas 1987
Texas 1987
Bamberger Group Texas Reintroduction 2003
Bamberger Group Texas Reintroduction 2004
Bamberger Group Texas 2004
Bamberger Group Texas Reintroduction 2004
Bamberger Group Texas Reintroduction 2004
Bamberger Group Texas Reintroduction 2004
Bamberger Group Texas 2004
Bamberger Group Texas Reintroduction 2004
Bamberger Group Texas Reintroduction 2004
Texas 2013
Texas 2013
Unknown Texas Reintroduction Unknown

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