Spicebush Swallowtail

Tragic events of September 11, 2001 have consolidated national pride and promoted the need to preserve American heritage. The United States is blessed with a fabulous diversity of native wildlife, from grizzly bears and giant redwood trees to delicate winged jewels, the butterflies and moths, and myriad of wildflowers. Each of these treasures, no matter how large or how small, deserves a place in this country to enrich lives and to confirm a healthy environment for future generations of Americans.

In 1984, the Center for Plant Conservation (CPC) in St. Louis formed a network of botanical gardens throughout the United States and territories to serve as a seed bank for those native American plants under threat of extinction. In Texas, this responsibility is shared by Mercer Arboretum & Botanic Gardens, San Antonio Botanical Garden, and The Lady Bird Johnson Wildflower Center in Austin.

The work to study these plants, protect their habitats, and relocate endangered plants to secure habitats is accomplished by volunteers, landowners, colleges, universities, and government and private organizations. Funds are also provided by CPC endowments dedicated to these plants.

Spicebush Swallowtail Catepillar (Photo by Carlos Hernandez)

The rare pondberry (Lindera melissifolia), a floodplain shrub, is one of over 15 species maintained for the CPC at Mercer and only exists in the wild in a few midwest and southeast states. Mercer’s pondberry is sponsored by Alice C. Fick of Auburn, Alabama in memory of Kenneth C. Beighley and by the Edward K. Love Conservation Foundation of St. Louis.

Often it is forgetten that America’s native plants are the foundation of the food chains for native animals (and humans). Caterpillars are the immature stage of the life cycle of butterflies, and, often both require very specific plants as their food source. Pondberry and spicebush shrubs (Lindera species), sassafras (Sassafras albidum), and a few additional members of the laurel and magnolia families are native host plants for the caterpillars and native spicebush swallowtail butterfly (Papilio troilus). Spicebush swallowtails follow the ranges of the caterpillars’ native host plants from southern Canada to Florida and west to Oklahoma and Central Texas.

The rare white bladderpod (Lesquerella pallida) and large-fruited sand verbena(Abronia macrocarpa) of East Texas are fully sponsored by CPC endowments by The Quaker Hill Foundation of Wayzata, Minnesota and the Houston families of Sellers J. Thomas, Frank A. Liddell, Jr., and Charles F. Squire for Mercer.

White Bladderpod (Photo by Greg Wieland)

Texas trailing phlox (Phlox nivalis ssp texensis) is currently in reintroduction into its historical range, The Big Thicket National Preserve of the National Park Service (NPS) in Hardin County, Texas. The Garden Club of Houston, River Oaks Garden Club of Houston, Magnolia Garden Club of Beaumont, U.S. Fish & Wildlife Service, The Texas Nature Conservancy, and Sam Houston State, Lamar, and Stephen F. Austin State universities are working together with the NPS to support these reintroductions. Recently, a CPC endowment for Texas trailing phlox has been initiated by a sponsorship from longtime Mercer volunteer, Carol Kobb of Conroe, in memory of her friend, Millie Gaudino of Houston.

Over 500 species in the CPC’s National Collection of Endangered Plants, including those maintained by Mercer, may be viewed and studied at www.mobot.org/CPCVanishing Wildlife of Texas, by John and Gloria Tveten and published by the Endangered Species Media Project (www.vanishingwildlife.com), provides a wealth of information about endangered plant and animal treasures.

 

 

 

 

Anita A. Tiller, Botanist
Mercer Arboretum & Botanic Gardens
Adapted from Parkscape, Spring 2002

Mercer Botanic Gardens is not only active in cultivating and expanding its gardens, but the park continues to grow its role in plant conservation, preservation, and research. To provide much-needed space for these efforts, Precinct 4 has established the Mercer Botanical Center.

“Loss of habitat, introduction of foreign species, and over-collection are putting many of our native plants in danger of extinction,” says Darrin Duling, director at Mercer. Out of 20,000 native plant species in the U.S., 200 species have become extinct and over 750 species are federally listed as endangered or threatened. “Loss of native plant species weakens the natural ecosystem, reduces the beauty and diversity around us, and depletes an irreplaceable gene pool that may hold the cures for diseases,” Duling explains. “The Mercer Botanical Center will help in our efforts to study and conserve these and other species.”

Located in the former Precinct 4 regional office at the corner of Titleist Drive and Aldine Westfield Road, the 3,100-square-foot Botanical Center houses Mercer’s expanding library, an herbarium, archives, a rare native plant seed bank, laboratories, and additional office space and conference rooms for research staff, visiting scientists, and volunteers.

According to Anita Tiller, Mercer’s Botanist and conservation manager, the second floor of the center is dedicated to Mercer’s archives and its rapidly expanding herbarium collection, which contains approximately 5,000 carefully prepared dried plant specimens for reference and research. “Herbarium specimens provide sources of DNA for use in studying taxonomy and the relationship between plants, which serve as the best source of reference material for plant identification,” she explains. She adds that herbarium specimens help to document changes in the distribution of vegetation over time and, in turn, help track changes in climate. Mercer’s herbarium houses collections that include flora from the unique saline prairies found in the Houston metro area and East Texas, as well as specimens from Mercer’s own living garden collections. “We plan to digitize images of our herbarium specimens for online reference,” she notes, adding that the herbarium is available to researchers by appointment and supports herbarium training classes for citizen scientists and students. Due to its nature as a working research facility, it is not open to the general public.

The first floor of Mercer’s Botanical Center houses Mercer’s reference library, laboratories, and staff offices. Dedicated lab space is used for maintaining the seed bank of rare native flora for the National Collection of Endangered Plants and for preparing specimens for Mercer’s herbarium. Future plans include adding a small plant propagation greenhouse for the labs, which will house plants grown for restoration needs.

The Botanical Center also supports research on Precinct 4’s Prairie Dawn Preserve, located near Cutten Road and West Greens Road, which is registered with the Native Prairies Association of Texas. Mercer was awarded a grant by the Lady Bird Johnson Wildflower Center in 2012 to develop a restoration plan for that preserve and the endangered native plant species found there, including the prairie dawn (Hymenoxys texana), Houston camphor daisy (Rayjacksonia aurea), and Texas windmill grass (Chloris texensis). These species can be seen on display in Mercer’s Endangered Species Garden.

“The Mercer Botanical Center gives us the space needed to continue and expand our efforts in helping to conserve rare and endangered plants,” Duling says.

Conserving Rare, Endangered Plants (PDF)

Adapted from Update, Fall/Winter 2014
Harris County Precinct 4
www.hcp4.net/mercer/conservation
Updated July 23, 2015

How Gardeners Can Help Save America’s Vanishing Flora

Long before America became a nation of gardens, it was called a Garden of Eden, blessed with lush, unique native flora. Now, that natural bounty is about to slip through our fingers – but America’s gardeners can help save it. At the Center for Plant Conservation, we’re working to conserve, preserve and restore our most vulnerable native plants. We need the collaboration of green thumbs around the country to make sure that all of our gardens – both planned and natural – can thrive.

What can gardeners do to help preserve America’s vanishing flora?

Horticultural enthusiasts can help imperiled native flora in many ways! Botanical gardens and arboreta such as Mercer Arboretum & Botanic Gardens and the 31 other institutions that participate in the CPC network often need volunteers to help store seed, monitor plants, locate hidden populations, transplant propagules, or care for seedlings in the greenhouse. Or, you could help in the office by recording data.

By becoming a friend of CPC, or by sponsoring a plant in our national collection, you can speed recovery efforts for our nation’s most vulnerable plants and wildflowers. Of the 24-species maintained by Mercer Arboretum & Botanic Gardens for the CPC’s National Collection, most are in need of sponsorship. Visit Mercer’s Endangered Species Garden to learn more about these plants, or visit Mercer’s conservation Web pages at www.cp4.hctx.net/ mercer/conservation.htm. To learn more about endangered plants outside of East Texas, visit CPC’s Web site at www.centerforplantconservation.org, or call (314) 577-9540 for more information.

Gardeners can also help by becoming more aware and spreading the word about the importance of saving our vanishing flora. Did you know that five percent of all native U.S. plants are federally listed as endangered, threatened, or a candidate for listing? Yet many people, including our leaders, know very little about the importance of native flora, and too little is allocated to fund native plant conservation. Our decision-makers need to know that you care about preserving the many benefits brought by native plants. Use your voice at the local or national level to share awareness of the plight of vulnerable native plants.

In your own garden, you can help by avoiding the introduction of invasive exotic species, which take over habitat and crowd out vulnerable natives.

Can Mercer or CPC send me seeds of imperiled plants?

Sorry, but no. Botanists throughout the CPC network of participating institutions collect and store seeds to hold in protective custody for our National Collection of Endangered Plants. Maintaining a complete, genetically representative sampling of seeds is vital to preserve restoration options for the future. Propagated plants are used by conservationists to restore populations of these valuable natural resources to the wild, and to recreate lost habitat. These seeds are needed for conservation work. Plus, distribution of endangered plants is regulated by law, although some nurseries may have permits to sell specific plants.

Is it okay to collect rare wildflowers?

Please do not collect seeds, roots, or other plant parts from imperiled, rare, or locally rare wildflowers or plants. It is illegal to disturb federally endangered plants on public land, and casual collecting can dramatically harm plants that are already at risk! Instead, seek out plants that are lawfully propagated by a responsible nursery – or choose a close relative that is not imperiled for your home garden.

Can I help save endangered plants by growing them in my garden?

In most cases, unfortunately, no. The goal of plant conservation is to maintain the genetic resources of rare and at-risk plants in order to preserve options for restoration to the wild.

Genetic diversity is usually much greater in plant populations growing in the wild. Plants grown in gardens will experience different kinds of genetic shifts than those grown under wild conditions, because they won’t experience the same interactions with soil, animals, weather, and other natural phenomena. Germinating and cultivating imperiled plants to maintain wild levels of diversity is carried out by trained conservation botanists under strict controls that cannot be duplicated in a backyard garden.

Garden versions of imperiled species might even alter the genetics of the wild population if they’re close enough to be cross-pollinated!

On the other hand, a garden of native plants not facing risk of extinction can be a beautiful way to celebrate local natural heritage. See reverse for resources.

 

The National Collection of Endangered Plants

Some wild strains of native plants are closely related to the horticultural varieties that grace backyards and award-winning gardens. And some of these wildflowers are dwindling to dangerous scarcity. You can help ensure long-term care and security of these species by helping to sponsor a plant in CPC’s National Collection of Endangered Plants.

The national collection is a bank of seeds, cuttings and other plant material from more than 600 of the country’s most imperiled native plants. Botanists at CPC participating institutions gather and catalog these plant materials according to strict standards developed by CPC’s Science Advisory Council. The materials are then stored and maintained in protective custody at the participating institution, preserving our options for restoration. Generous donors help support the maintenance and research of plants in our collection.

Is there a relative of one of your garden favorites that needs sponsorship? Check Mercer’s list of plants in need of sponsorship below, or browse the complete collection online at www.centerforplantconservation.org.

 

Resources

♦ You can find native plant nurseries and seed suppliers, native plant organizations, and a database of native plants for every state, all at The Lady Bird Johnson Wildflower Center’s website: www.wildflower.org

♦ Visit Mercer’s Visitor Center and ask for a list of nurseries in the Houston area that stock native seeds and plants.

♦ Study the displays of native plants throughout Mercer especially those in the Endangered Species Garden. This garden is a certified Wildscape Demonstration Garden by Texas Parks & Wildlife Department and The National Wildlife Federation.

♦ Visit The Texas Parks & Wildlife Department at www.tpwd.state.tx.us and The National Wildlife Federation at www.nwf.org, to learn more about landscaping your yard with native plants and “wildscaping.”

♦ Join Mercer as a volunteer and/or become a Master Gardener and learn firsthand how to raise native plants.

♦ Texas Parks & Wildlife, www.tpwd.state.tx.us, will train you how to conserve native plants as a Texas Master Naturalist.

♦ The Native Plant Society of Texas, www.npsot.org, holds regular talks, meetings, and outings as well as distributes a newsletter. It’s a good way to meet other native plant enthusiasts, many of whom will be willing to share their expertise.

♦ Learn more about invasives. Visit the National Park Service’s alien plant pages at www.nps.gov/plants/alien/index.htm . Examine voluntary codes of conduct from the “Linking Ecology and Horticulture to Prevent Plant Invasions” workshop at www.mobot.org/invasives.

Plant Conservation for Gardeners (PDF)

The word endangered is often used to refer to wildlife in danger of extinction. But plants also suffer from situations that dwindle the wildlife population.

The Texas trailing phlox is just one of more than 30 endangered plant species maintained by Mercer.

Loss of habitat, introduction of foreign species, and over-collection are just a few of the threats to the nation’s 20,000 native plant species. Already, more than 200 species have become extinct and over 730 species are federally listed as endangered or threatened. Loss of native plant species weakens the natural ecosystem and depletes an irreplaceable gene pool that may hold the cures for diseases, such as certain forms of cancer.

Mercer Arboretum & Botanic Gardens plays a unique role in saving dwindling plant populations. Mercer works with the Center for Plant Conservation (CPC), and is the only botanic garden in the upper Gulf Coast region certified to care for the CPC’s national collection of endangered plants. In addition, Mercer maintains species from other botanic facilities such as the Arnold Arboretum of Harvard University in Massachusetts; Historic Bok Gardens in Lake Wales, Florida; and the San Antonio Botanic Gardens.

“Restoring the population of a single plant species is a long-term commitment and a big job!” says Dr. Kathryn Kennedy, CPC president and executive director. From collecting endangered seeds in the wild to carefully cultivating and restoring a plant’s gene pool, the process is exacting and costly. Costs include items like field equipment, travel costs, seed cleaning, packaging supplies, and horticultural supplies.

Although Mercer receives annual maintenance funds from the CPC to support plant restoration activities of several species, it is still in need of additional funding to care for additional CPC-endangered plants. Depending on the level of sponsorship, gifts include framed color prints, T-shirts, note cards, and other gifts featuring a sponsored plant. Sponsors are acknowledged in Precinct 4 publications and events referencing their species, honored on plaques at Mercer, and featured on Mercer’s Web site. Sponsorship donations range from $200 to $10,000 for a full sponsorship of a single endangered species.

To view endangered plants in need of sponsorship, please click here.

Anita A. Tiller, Botanist
Mercer Arboretum & Botanic Gardens
Adapted from Parkscape, Spring 2003

Mercer Arboretum & Botanic Gardens is a member of the Center for Plant Conservation’s (CPC) National Collection of Endangered Plants, a network of botanical facilities throughout the United States and territories. The National Collection maintains the largest collection of rare plants in the world. As part of The National Collection, Mercer now banks seed and live plants for 18 species.

Southern Lady’s Slipper Orchid

The southern lady’s-slipper orchid (Cypripedium kentuckiense), also known as Kentucky lady’s-slipper orchid, assigned to Mercer by the CPC in 2002, is a stunning wildflower. Joe and Ann Liggio describe this species in their comprehensive reference:Wild Orchids of Texasas “Perhaps the most spectacular of the 54 kinds of orchids in Texas.” The southern lady’s-slipper orchid is one of the 50 lady’s-slipper orchid species found in Europe, Asia, and North America. This lady’s-slipper orchid has a chicken-egg-sized, cream to golden-yellow, pouch-like petal. The pouch, or “slipper,” is draped by a sepal and flanked by two petals that “dangle to the sides like unfastened shoelaces.” These sepals and petals range from deep maroon to yellow-green with maroon mottling. The flowers may span over eight inches. Sepals and petals are modified leaves that are attached to the male and/or female reproductive structures of flowers. In many flowering plants, the sepals often are green and the showy petals are variously colored; however, when the petals and sepals are similar in appearance, they are then termed tepals. The termCypripediumis derived from Kypris, the Greek name for Venus andpediumfor “little foot” or “slipper.”

The southern lady’s-slipper orchid, the largestCypripediumin North America, may stand over two feet tall and bears three to five eight-inch long pleated leaves that spiral up each side of the stem. This orchid inhabits isolated areas in East Texas, Oklahoma and the southeastern United States. In Texas,Cypripedium kentuckienseoccurs in approximately one dozen locations and is most often found in sheltered ravines with American beech, white ash, black gum, southern magnolia, flowering dogwood, red and chalk maple, big-leaf snowbell, American hornbeam, maple-leaf and arrow wood viburnum, walter’s violet, and slender wake-robin trillium.

The cosmopolitan orchid family is one of the largest and most diverse families of plants. Orchids inhabit every continent except Antarctica. Orchids of temperate regions are primarily terrestrial (root in the ground) and range north into the arctic and to the southern tip of Argentina’s Tierra del Fuego. Most epiphytic orchids (air plants) are restricted to the sub-tropics and tropics, and grow on other plants without harming them. Epiphytic orchids possess specialized aerial roots covered in layers of spongy, water and mineral-absorbing cells.

The vine-likeVanilla planifoliais the most economically important orchid as it produces the pod-shaped fruit (capsule) from which vanilla extract is obtained.Vanillaplanifoliagrows in Florida, the West Indies and Central and South America. The hardy ground orchid (Bletilla striata) is a terrestrial species from China and Japan and is grown at Mercer as a perfect perennial for woodland gardens. Epiphytic orchids receive the most horticultural interest and are bred for their almost limitless diversity in form, scent, and color. Traditional orchids used in prom corsages include theCattleya orLaeliafrom tropical Central and South America and the West Indies. Florists now offer Asian and Australian orchids (Cymbidium,Dendrobium), Moth Orchids (Phalaenopsis), and other species as alternatives for formal events. Many of these exotic orchids are easily grown as houseplants.

Whereas flowers typically offer gifts of pollen or nectar as food to ensure the cross-pollination by their hungry pollinators, many wild orchids offer “romantic” rewards to amorous insects. Males of specific species of wasps and bees are drawn to specific orchid flowers that mimic the females of their species. These flowers mimic the female insect in shape, color, texture, and scent. As the male insect courts one “female” after the next, they effectively cross-pollinate the flowers.

Bees and wasps in search of nectar are pollinators ofCypripedium kentuckiense, which is threatened by logging, development, and by over-collection by plant enthusiasts or collectors of traditional medicines. ThisCypripediumis extremely sensitive to disturbance and as for most orchids, must grow in association with specific soil fungi in order to survive. All orchids produce minute, dust-like wind-dispersed seed that often require several years to produce flowering plants. Interestingly, some people experience an allergic skin reaction after contact withCypripediumorchids.

The southern lady’s-slipper orchid is a unique and fragile treat for visitors to view as a spring wildflower in the proposed woodland habitat of Mercer’s Endangered Species Garden.

 

Anita A. Tiller, Botanist
Mercer Arboretum & Botanic Gardens
Adapted fromParkscape, Winter 2002
Photo by Joe Liggio

Texas Trillium blooms in March at Mercer’s conservation nursery.

Mercer Botanic Gardens is one of 38 leading botanical gardens and arboreta in the United States that collectively maintain over 750 species for the Center for Plant Conservation’s (CPC) National Collection of Endangered Plants. The CPC preserves rare, native (American) plants in a centralized network of botanical institutions within 17 states and the Virgin Islands. In Texas, Mercer Botanic Gardens, San Antonio Botanic Gardens, and The Lady Bird Johnson Wildflower Center share the responsibility for the preservation of rare plants within seed banks or as live specimens. In addition to the CPC institutions mentioned above, The Arboretum at Flagstaff and the Desert Botanical Garden of Arizona maintain the rare mountain and desert species for Texas. To preserve the nation’s rare botanical treasures, Mercer and the CPC’s other member institutions hold partnerships with concerned citizens, private and government conservation organizations, universities, and colleges.

In 2000, the CPC assigned Mercer the maintenance of the Texas trillium, which is over-collected from the wild and under threat from loss of habitat. The name trillium indicates that the arrangement of the flower parts and leaves are in groups of threes. Trilliums, often known as trinity lilies, wake-robins, or wood lilies, are unique spring-blooming wildflowers that form large localized colonies by means of their underground stems and by the germination of their seed.

Found in the Piney Woods of East Texas and in northwestern Louisiana, Texas trillium stands up to 12 inches tall, bears one or three leaves in whorls, and each petal that is 1.25 to 1.5 inches long begin as snow-white and then blush pink to magenta as they age. They complete flowering in the spring and rest during the hot months as underground stems. Shoots reappear from these perennial plants in late winter to early spring in shady, low, and moist wooded stream-banks and sphagnum bogs (baygalls) often with sweetbay magnolia, red maple, black gum, wax myrtle, and Virginia sweetspire trees.

The 43 species of trilliums that grow in North America and Asia are considered by gardeners as among the most beautiful of wildflowers and sentinels of spring by outdoor enthusiasts. Once considered a part of the lily (Liliaceae) family, trilliums are now included in the bunchflower family (Melanthiaceae) due to their unique characteristics. All trilliums bear a whorl of three leaf-like bracts below three colored petals. The showy flowers serve as signals to their pollinators and the odor of the flowers vary among the species. Trilliums with sweet smelling flowers signal to butterflies, bees, and wasps, whereas species like stinking trillium (T. foetidissimum), the Latin word for fetid or foul, of Louisiana and Mississippi signal to their pollinators, the flies. Species including the stinking trillium that are pollinated by flies often have dull brown or maroon flowers and the smell mimics rotting flesh. Often called birthwort, beth root or Indian balm, certain trilliums contain chemicals that are used medicinally as astringents, coagulants, expectorants and uterine stimulants. The plants, however, are generally considered toxic.

Partners assisting Mercer with the maintenance of the Texas trillium for the CPC include Stephen F. Austin State University, the Texas Nature Conservancy, the Coastal Crossroads Chapter of the Texas Native Plant Society, Lady Bird Johnson Wildflower Center, and Texas Parks & Wildlife Department (TPWD). Mercer’s conservation volunteers and partner biologists monitor wild populations for the Texas Natural Diversity Database Program and help collect seed stock for the CPC National Collection of Endangered Plants. The Texas Natural Diversity Database Program is a member of NatureServe, an international network of natural heritage programs and conservation data centers found in all 50 U.S. states, Canada, Latin America and the Caribbean.

In addition, Ohio’s Cincinnati Zoo & Botanic Garden’s Center for Research of Endangered Wildlife (CREW), also a certified CPC participating institution, has worked in partnership with Mercer for several years. CREW applies state-of-the-art technology to preserve the genetic diversity of rare exotic and native animals and plants. Dr. Valerie Pence heads the plant tissue culture and cryogenic (long-term freeze storage) laboratories.

Several of the rare plants maintained at Mercer including the Texas trillium are a challenge to propagate. All trilliums are notoriously difficult to germinate from dry seed. Reportedly, one batch of dry seed requires over 20 years to germinate after planting! Fresh seed from trilliums usually require two spring seasons to germinate and require several years of growth prior to bloom. Because of this, Dr. Pence and CREW are developing methods to generate cultures of trilliums from sections of the underground stems and from the embryos within fresh seed. Mercer has successfully coaxed Texas trilliums to bloom within the conservation section of the shade nursery (see photo), and is testing short-term storage techniques of the underground stems by extending their dormancy at refrigerated temperatures.

Future plans at Mercer include developing a public display of rescued Texas trilliums in the Endangered Species Garden that displays a number of America’s native endangered plants on a seasonal basis. In 2004, Texas Parks and Wildlife and the National Wildlife Federation awarded Mercer’s Endangered Species Garden the Best of Backyard Habitats certificate. In 2009, the North American Butterfly Association certified the garden as a butterfly garden. Mercer’s Endangered Species Garden serves as an educational tool for the importance of “wildscaping,” demonstrating the use of permanent water and food sources, composting, and organic management methods to benefit wildlife. Common native plants complement the rare species in this display garden and provide examples for home landscapes.

Adapted from Harris County Precinct 4’s Parkscape, Summer 2002
Anita A. Tiller, Botanist
Mercer Botanic Gardens
Photo by Suzzanne Chapman
Updated February 28, 2012
www,hcp4.net/mercer/conservation


References

Case, F. W., Jr. , and R. B. Case. 1997. Trilliums. Portland, Ore.: Timber Press. 285 pp.

Center for Plant Conservation (CPC). 2012. National Collection of Endangered Plants. www.centerforplantconservation.org

Diggs, G. M., Jr., B. L. Lipscomb, M. D. Reed and R. J. O’Kennon. 2006.Illustrated Flora of East Texas. Vol. 1 Introduction, Pteridophytes, Gymnosperms and Monocotyledons. SIDA, Bot. Misc.16. Fort Worth: Botanical Research Institute of Texas. 1594 pp.

Farmer, S.B. and E. E. Schilling. 2002. Phylogenetic analysis of Trilliaceae based on morphological and molecular data. Syst. Bot. 27: 674-92.

Flora of North America North of Mexico 2002. Edited by Flora of North America Editorial Committee, vol. 26, New York and Oxford University Press, New York. 723 pp. available on-line: www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=133668

Judd, W.S., et al. Plant Systematics A Phylogenetic Approach. Second Edition. 2002. Sinauer Associates, Inc. Sunderland, MA. 576 pp.

Lawrence, G. H. M.. Taxonomy of Vascular Plants. 1951. Macmillan. New York. 823 pp.

MacRoberts, M. H., and B. R. MacRoberts. 2001. Bog communities of the West Gulf Coastal Plain: A profile. Bog Research Papers in Botany and Ecology 1:1-151.

Poole, J.M., W. R. Carr, D. M. Price and J. R. Singhurst. Rare Plants of Texas. 2007. A&M Univ. Press College Station, TX. 640 pp.

Reid, C. 2004. Rare plant species of Louisiana- May 2004. Baton Rouge: Louisiana Natural Heritage Program.

Singhurst, J. R., E. S. Nixon, W. F. Caldwell and W. C. Holmes. 2002. The genus Trillium (Liliaceae) in Texas. Castanea 67:316-23.

Large-Fruited Sand Verbena

Mercer Botanic Gardens is one of 38 leading botanical gardens and arboreta in the United States that collectively maintain over 750 species for the Center for Plant Conservation’s (CPC), National Collection of Endangered Plants. The CPC preserves rare, native (American) plants in a centralized network of botanical institutions within 17 states and the Virgin Islands. In Texas, Mercer Botanic Gardens, San Antonio Botanic Gardens, and The Lady Bird Johnson Wildflower Center share the responsibility for the preservation of rare plants within seed banks or as live specimens. In addition, the CPC institutions, The Arboretum at Flagstaff and Desert Botanical Garden of Arizona, maintain the rare mountain and desert species for Texas. In order to preserve the nation’s rare botanical treasures, Mercer and the CPC’s other member institutions hold partnerships with concerned citizens, private and government conservation organizations, universities, and colleges.

The large-fruited sand verbena (Abronia macrocarpa), listed as endangered by the federal and Texas governments in 1988, is one of Mercer’s “charter” species. In 1990, the large-fruited sand verbena received full sponsorship for the CPC through generous donations from The Quaker Hill Foundation. The large-fruited sand verbena benefits from annual sponsorship stipends directed to Mercer for equipment and supplies for the plant’s recovery.

First discovered in 1968 by doctors Helen and Donovan Correll and described as a new species in 1972, Abronia macrocarpa occurs only in the sand dune habitats of post oak savannas in three east-central Texas counties: Freestone, Leon, and Robertson. The large-fruited sand verbena is an herbaceous perennial and is extraordinarily well-adapted to drought conditions by virtue of its persistent taproot and ability to remain dormant during the hot summer months. The magenta, golf-ball-sized flower heads of this wildflower typically appear following spring rains, and they produce an intense, sweet perfume at dusk. Fall rains occasionally stimulate a second bloom season.

Contrary to its common name, the large-fruited sand verbena is a member of the four-o’clock (Nyctaginaceae) family that includes the popular garden annual four-o’clock (Mirabilis) and the sub-tropical vine bougainvillea. In the United States, members of the Nyctaginaceaefamily mostly occur in the southern and Pacific regions.

Although hummingbirds typically pollinate bougainvillea, moths are important pollinators of many of the four-o’clock species and the sweet-scented Abronia macrocarpa. Mercer’s conservation partners, Dr. Paula Williamson and her students at the Texas State University-San Marcos, and Gena Jannsen of Janssen Biological, study the genetic diversity and biology of the endangered Abronia and monitor wild populations for the Texas Diversity Database Project. These partners also collect seed stock for the CPC’s National Collection of Endangered Plants. The Texas Natural Diversity Database Program is a member of NatureServe, an international network of natural heritage programs and conservation data centers found in all 50 U.S. states, Canada, Latin America and the Caribbean.

Dr. Williamson and her research group documented that hawk and noctuid moths are attracted to the perfume released from the open Abronia flowers at dusk. Pollination by these moths occurs until the Abronia’s flowers close in the morning. Cross-pollination between individual plants of this wildflower is required for the production of fertile seeds within Abronia macrocarpa’s characteristic large, five-winged fruits called “anthocarps.” The wings on the anthocarps serve to assist dispersal of the seed by wind. However, researchers have found that seed are rarely dispersed more than a foot from the mother plants. Ants are instrumental in gathering the seed and uneaten seed will germinate in the ants’ underground nests.

During April of 2010, Elizabeth Saunders, Ph.D., candidate of Southern Illinois University Carbondale, visited Mercer’s Endangered Species Garden. By means of a portable vacuum pump, she captured the scent from the open flowers of Abronia macrocarpa. Saunders is studying the relationship between pollinators and the chemical makeup of the scents of the 20, or so, species of sand verbenas found in North America. Her studies hope to reveal insights about the evolution of floral scents and its relationship with pollinators.

Abronia macrocarpa’s restricted occurrence within sites under threat from commercial development and invasive plant species has made wild populations of the plant especially vulnerable. Successful partnerships currently underway with private landowners where the large-fruited sand verbena exists in the wild will help preserve this endangered plant species.

The large-fruited sand verbena typically blooms during March and April and is displayed with other rare Texas plants in Mercer’s Endangered Species Garden. Awarded the Best of Backyard Habitats certificate by Texas Parks and Wildlife and the National Wildlife Federation in 2004, and certified as a butterfly garden by the North American Butterfly Association in 2009, the Endangered Species Garden serves as an educational tool for the importance of “wildscaping,” demonstrating the use of permanent water and food sources, composting, and organic management methods to benefit wildlife. Common native plants complement the rare species in this display garden and provide examples for home landscapes.

Anita A. Tiller, Botanist
Mercer Botanic Gardens
Adapted from Parkscape, Summer 2001
Photo by Suzzanne Chapman
Updated February 28, 2012

References

Center for Plant Conservation (CPC). 2010. National Collection of Endangered Plants. www.centerforplantconservation.org

Flora of North America North of Mexico. Volume 4. 2003. Edited by Flora of North America Editorial Committee. Oxford University Press, New York. 559 pp. Available online: www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=100040

Judd, W.S., et al. Plant Systematics: A Phylogenetic Approach. Second Edition. 2002. Sinauer Associates, Inc. Sunderland, MA. 576 pp.

Lawrence, G. H. M. Taxonomy of Vascular Plants. 1951. Macmillan. New York. 823 pp.

Poole, J. M.; Carr, W. R.; Price, D. M.; and Singhurst, J. R. Rare Plants of Texas. 2007. A&M Univ. Press College Station, TX.

Williamson, P.S.; Bazeer, S.K. 1997. Self-incompatibility in Abronia macrocarpa(Nyctaginaceae). Southwestern Naturalist. 42: 409-415.

Williamson, P.S.; Muliana, L.; Janssen, G.K. 1994. Pollination biology of Abronia macrocarpa (Nyctaginaceae), an endangered Texas species. Southwestern Naturalist. 39: 336-341.

Williamson, P.S.; Werth, C.R. 1999. Levels and patterns of genetic variation in the endangered species Abronia macrocarpa Galloway (Nyctaginaceae).American Journal of Botany. 86, 2: 293-301.

Rare Houston Camphor Daisy

Mercer Botanic Gardens is one of 38 leading botanical gardens and arboreta in the United States that collectively maintains over 750 species for the Center for Plant Conservation’s (CPC) National Collection of Endangered Plants. The CPC preserves rare, native (American) plants in a centralized network of botanical institutions within 17 states and the Virgin Islands. In Texas, Mercer Arboretum & Botanic Gardens, San Antonio Botanic Gardens, and The Lady Bird Johnson Wildflower Center share the responsibility for the preservation of rare plants within seed banks or as live specimens. In addition to the CPC institutions mentioned above, The Arboretum at Flagstaff and the Desert Botanical Garden of Arizona maintain the rare mountain and desert species for Texas. To preserve the nation’s rare botanical treasures, Mercer and the CPC’s other member institutions hold partnerships with concerned citizens, private and government conservation organizations, universities, and colleges.

The CPC assigned Mercer the maintenance of the Houston Camphor Daisy in 1996. The unique prairie habitat that the Houston camphor daisy thrives in is vulnerable to development as well as invasive species, namely the Chinese tallow tree. Prior to development, periodic natural fires and ranging herds of bison reduced competition from other plants and maintained open prairie habitats. Historically, the Houston camphor daisy occurs on “pimple mounds” or “mima mounds,” or natural bare spots in the native coastal prairies. Today, periodic mowing, carefully managed cattle grazing, and prescribed burns help to maintain prairie habitats. This tap-rooted annual grows to 20 inches tall and has branched stems that bear elongated, smooth-edged or sparsely-toothed, one to two inch long leaves. The Latin word “aurea” used to describe Rayjacksonia aurea denotes the golden-yellow color of the ray and disc flowers. The bright yellow heads of the Houston camphor daisy grow to just over one-half inches across and cover the plants in the fall.

Composed of approximately 25,000 members, the Asteraceae family is also called the composite, sunflower, or daisy family and occurs worldwide, except in Antarctica. With approximately 620 species recorded in Texas, the Asteraceae family is one of the largest families of plants in Texas.

In the composite family, blooms are typically arranged as a “head” composed of many small flowers attached to a base also known as the “receptacle.” In many composites, including the Houston camphor daisy, the outer or marginal flowers of the head have a single, showy, petal-like strap and are referred to as “ray flowers.” The interior, tube-shaped flowers are called the “disc flowers.” The “petal” of a daisy is actually a petal-like strap from one individual ray flower. The ray flowers form a circle at the outer margin of the daisy’s head and the many disc flowers form the center of the head. Common garden favorites including sunflowers, asters, and daisies are composites that often display the ray and disc flower arrangement shown by Rayjacksonia.

In addition to ornamental merits, the Asteraceae family provides important food sources: sunflowers (Helianthus, a crop native to America), lettuce (Lactuca), artichoke (Cynara), safflower (Carthamus), salsify (Tragopogon), chicory and endive (Cichorium). Other Asteraceae plants of economic importance include the Chrysanthemum coccineum, which provide the insecticide pyrethrum, and red dye safflower (Carthamus tinctoria).

In the Asteraceae family, the single seed produced from a fertile flower is enclosed within a dry, thin-shelled fruit named an “achene” or “cypsela.” The fruits produced by the ray and disc flowers are crowded within each head of a Houston camphor daisy. Sunflower seeds are popular examples of the fruits formed by members of the composite family.

The three annual herbs identified as Rayjacksonia, Houston camphor daisy, viscid camphor daisy and Gulf coast camphor daisy, occur only in North America. All three display yellow flowers and emit an aromatic camphor-like odor that reportedly repels browsing deer. The viscid and Gulf Coast camphor daisies occur in the Rio Grande and Gulf Coastal Plains, and extend into the central and southern states and Mexico. The rare Rayjacksonia aurea, however, occurs only in Harris and Galveston counties as a pioneer plant of barren soils.

The Houston camphor daisy is often associated with the rare Texas windmill grass (Chloris texensis) and prairie dawn (Hymenoxys texana), which Mercer also maintains for the National Collection of Endangered Plants. These three plants are endemic (native) to the coastal plain of southeast Texas, and are part of over 300 plants that are endemic to Texas and found nowhere else on Earth. Texas supports a vast diversity of butterflies, birds, and other wildlife that migrate through and inhabit the state’s prairies. The wildlife is directly dependent upon the nectar, forage, and seed provided by Texas prairie wildflowers and grasses.

Conservation volunteers, partners, local botanists including Dr. Larry E. Brown of the Houston Community College and Spring Branch Science Center, and biologists with the Texas Parks and Wildlife Department, Harris County Flood Control District, the U.S. Fish and Wildlife Service and the U.S. Army Corps of Engineers monitor local wild populations of Rayjacksonia aurea as well as other rare Harris County species for the Texas Natural Diversity Database Program. These volunteers and partners also help collect seed stock for the CPC National Collection of Endangered Plants. The Texas Natural Diversity Database Program is a member of NatureServe, an international network of natural heritage programs and conservation data centers found in all 50 U.S. states, Canada, Latin America and the Caribbean.

In addition to the rare Houston camphor daisy and prairie dawn, 76 other rare wildflowers in the family Asteraceae remain on the Texas rare plant watch list and include other species maintained by Mercer for the National Collection of Endangered Plants: white fire-wheel (Gaillardia aestivalis var. winkleri); rough-stem aster (Symphyotrichum puniceumvar. scabricaule); slender gay feather (Liatris tenuis); and bog coneflower (Rudbeckia scabrifolia). The rare Houston camphor daisy typically blooms from late September through December and is displayed with other rare Texas plants in Mercer’s Endangered Species Garden that was awarded the Best of Backyard Habitats by Texas Parks and Wildlife and the National Wildlife Federation in 2004, and certified as a butterfly garden by the North American Butterfly Association in 2009. The Endangered Species Garden serves as an educational tool for the importance of “wildscaping,” demonstrating the use of permanent water and food sources, composting, and organic management methods to benefit wildlife. Common native plants complement the rare species in this display garden and provide examples for home landscapes.

In 2005, the Houston Camphor Daisy received full sponsorship for the CPC through generous donations from Anita Tiller in memory of Michael H. Tiller, Aveda Cosmetics, Crouch Environmental Services, Inc., Lakewood Forest Garden Club, and Suzzanne Chapman in honor of Blanca and William Othon. The Houston camphor daisy benefits from annual sponsorship stipends directed to Mercer for travel costs to collect seeds, equipment and supplies for the plant’s recovery.

Adapted from Parkscape, Fall 2001
Harris County Precinct 4
Anita A. Tiller, Botanist
Mercer Botanic Gardens
Photo by Suzzanne Chapman
Updated February 29, 2012

 

References

Center for Plant Conservation (CPC). 2010. National Collection of Endangered Plants. www.centerforplantconservation.org
Flora of North America North of Mexico Volume 20. 2006. Edited by Flora of North America Editorial Committee. Oxford University Press, New York. 666 pp. Available online: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=128032

Judd, W.S., et al. Plant Systematics A Phylogenetic Approach. Second Edition. 2002. Sinauer Associates, Inc. Sunderland, MA. 576 pp.

Julien, P. 2001. Monitoring the threatened Houston daisy. The Texas Nature Tracker, Spring newsletter, p. 5.

Lane, M. A. and R. L. Hartman. 1996. Reclassification of North AmericanHaplopappus (Compositae: Astereae) completed: Rayjacksonia gen. Nov. Amer. J. Bot. 83: 356–370.

Lawrence, G. H. M. Taxonomy of Vascular Plants. 1951. Macmillan. New York. 823 pp.

Linam, L. A. 2000. Two for the prairie…gophers and daisies. The Texas Nature Tracker, Spring newsletter, p. 10.

Nesom, G. L. 2000. Generic conspectus of the tribe Astereae (Asteraceae) in North and Central America, the Antilles, and Hawaii. Sida, Bot. Misc. 20:1-100.

Poole, J.M., W. R. Carr, D. M. Price and J. R. Singhurst. Rare Plants of Texas.2007. A&M Univ. Press College Station, TX. 640 pp.

Rosen, D. J. and C. A. Yeargan. 2004. Survey for Rayjacksonia aurea andChloris texensis, Harris County Precinct 2, 24-acre prairie preserve, 23 November 2004. Texas Parks and Wildlife Files, Austin.

The white bladderpod was registered in 1987 as a federally endangered species.

The Center for Plant Conservation (CPC) preserves rare, native American plants in a centralized network of 38 botanical gardens within 17 states and the Virgin Islands. In Texas, Mercer Botanic Gardens, San Antonio Botanic Gardens, and The Lady Bird Johnson Wildflower Center share the responsibility for the preservation of  rare plants within seed banks or as live specimens. In addition, the CPC institutions, The Arboretum at Flagstaff, and the Desert Botanical Garden of Arizona maintain the rare mountain and desert species for Texas. In order to preserve the nation’s rare botanical treasures, Mercer and other CPC member institutions hold partnerships with concerned citizens, private and government conservation organizations, universities, and colleges.

Mercer maintains White Bladderpod (Physaria pallida) formerly known as Lesquerella pallida, a dainty, winter annual wildflower for  the CPC’s National Collection of Endangered Plants. White Bladderpod plants reach a maximum height of two feet with gray to yellow-green foliage. The Latin word “pallidus,” meaning pale, describes the less than one-inch-wide white flowers the plant bears in the spring. Each flower has a yellow eye and produces a ¼-inch pea, or “bladder-shaped” fruit in late spring to early summer.

Dr. M. C. Leavenworth discovered Physaria pallida on small prairies near San Augustine, Texas in the 1830s. The rare plant only occurs in the wild in San Augustine County, Texas, and grows on open, rocky outcrops of unusual geological regions called Weches formations. Weches formations are bands of ancient marine sediments that lie parallel to the Gulf Coast from Sabine to Frio Counties. In East Texas, these alkaline “islands” of soil contrast the surrounding acid soils of the Pineywoods. The thin top layer of these alkaline sediments contains fossilized calcium-containing marine shells and covers a layer of clay. In San Augustine County, this clay traps water and remains saturated during rainy periods. The clay then becomes very dry during the heat of the summer. The seeds of Physaria pallida normally germinate in the Weches clay after fall rains and the plants overwinter as small tap-rooted plantlets.

Because the White Bladderpod is isolated within this very unique habitat, it is vulnerable to development, mining and is threatened by competition from other plants. Prior to development, periodic natural fires would reduce competition from other plants.

The White Bladderpod’s cousin, Zapata Bladderpod (Physaria thamnophila), is another very rare Texas native and occurs only in Zapata and Starr counties in West Texas and Tamaulipas, Mexico. In addition, four other uncommon kinds of Physaria occur in Texas.

The White Bladderpod is a member of the large family of plants named the Brassicaceae Family. Over 4,000 members of this family occur worldwide and are often referred to as the Mustard or Cabbage Family. The cross-like arrangement of the four petals found on the flowers of the Mustard Family inspired the former botanical name, the Cruciferae Family. The family is also characterized as bearing two-chambered fruits called capsules or siliques.

Sixteen other rare wildflowers in the family Brassicaceae remain on the Texas rare plant watch list and include: Cardimine macrocarpa, Draba standleyi, Leavenworthia texana, Rorippa ramosa, two kinds of Selenia, Sibara grisea, six kinds of Streptanthus, Thelypodiopsis shinnersii, and two kinds of Thelypodium.  Leavenworthia texana, Texas Golden Glade Cress,  shares habitat with White    Bladderpod in San Augustine County, and also occurs in Sabine and Nacogdoches Counties. Like the White Bladderpod, Texas Golden Glade Cress and six other rare members of the Brassicacea listed above, are “endemic” to Texas, that is, these unique plants only occur in Texas. These wildflowers are important in that they provide nectar, forage, and seed for butterflies, birds, and other Texas wildlife. Mercer maintains seed of Texas Golden Glade Cress for the CPC’s National Collection of Endangered Plants, but this plant presently is not on display at Mercer. To view rare plants maintained by Mercer, visit www.hcp4.net/mercer/conservation.

The Brassicaceae Family is also economically important as food crops: mustard, kale, brussels sprouts, broccoli, cabbage, cauliflower, and turnips (kinds of Brassica),  horseradish (Armoracia), Japanese horseradish (Wasabia),   radish (Raphanus),  and watercress (Nasturtium) to name a few. In the 1960s, Canadian horticulturalists bred the nutritionally popular culinary oilseed crop, canola, from the Rapeseed plant, a member of Brassica group. Seeds of certain kinds of Physaria are currently under study as a source of fine oil for industrial and cosmetic use.

Many plants in the Mustard Family contain compounds that are irritating to animals eating them, and several  Shepherd’s-purse (Capsella), Mustards (Brassica and Barbarea), and Peppergrass (Lepidium) often are considered weeds.

Approximately 90 kinds of Physaria occur in North America and Greenland. The yellow-flowered Alpine  Bladderpod (P. alpina), a native of the Rocky Mountains, is grown in rock gardens of cool climates. The common Texas native, Big-flower Bladderpod (P. grandiflora) also bears yellow blooms and is used in sunny flower borders on well-drained soils. Other popular garden members of the Brassicaceae family include ornamental Cabbage and Kale (Brassica), Sweet Alyssum (Lobularia), Nasturtium (Tropaeolum),   Honesty (Lunaria), Wallflower (Erysimum), Basket-of-gold (Aurinia), Stock (Matthiola), Rocket (Hesperis), Candytuft (Iberis), and Rock Cress (Arabis).

Stop by Mercer’s Endangered Species Garden from January until May to see the White Bladderpod covered with snow-white flowers and again in late spring and summer when they are covered with bladderpods.

In 1999, Dr. and Mrs. Sellers J. Thomas, Jr.; Mr. Frank A. Liddel, Jr.; Dr. and Mrs. Charles F. Squire of Houston; and the U.S. Fish & Wildlife Service generously sponsored the White Bladderpod for the CPC. The White Bladderpod benefits from annual sponsorship stipends directed to Mercer for equipment and supplies for the plant’s recovery.

Adapted from Harris County Precinct 4’s
Parkscape newsletter, Winter 2001 issue
Anita A. Tiller, Botanist
Mercer Botanic Gardens
Photos by Suzzanne Chapman
www.hcp4.net/mercer/conservation
Updated February 28, 2012

References

Flora of North America North of Mexico Volume 7. Jan. 2007. Edited by Flora of North America Editorial Committee. Oxford University Press, New York. pp. 600 Available online: www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10120&key_no=8

George, R.J. 1987. The herbaceous flora of three Weches Formation Outcrops in eastern Texas. [M.S. thesis]: Stephen F. Austin State University, Nacogdoches.

Halstead, L. 2003. Conservation Area Plan for the San Augustine Glades, March 2003. The Nature Conservatory, San Antonio, TX.

Judd, W.S., et al. Plant Systematics A Phylogenetic Approach, Second Edition. 2002. Sinauer Associates, Inc. Sunderland, MA. pp. 576.

Lawrence, G.H.M.. Taxonomy of Vascular Plants 1951. Macmillan. New York. 823 pp.

Mahler, WM. F. 1987. Leavenworthia texana (Brassicaceae), A New Species from Texas. SIDA 12(1):239-242.

Mahler, WM. F. 1981. Notes on rare Texas and Oklahoma Plants. Sida 9(1): 239-242

Nixon, E.S.; Ward, J.R.; Lipscomb, B.L. 1983. Rediscovery of Lesquerella pallida (Crucifarae). Sida. 10: 167-175.