Archive for May, 2013
Currently blooming at the Smithsonian Gardens Greenhouses is a remarkable, large-growing epiphyte endemic to Borneo; Dimorphorchis rossii. As its name suggests, this formidable plant boasts dimorphic flowers, or two different flower forms on the same inflorescence.
The proximal flower morph (typically the first one to three flowers of the inflorescence) is a bright golden yellow and emits a strong fragrance during the day. The distal morph is white with faint pink spots, but has no detectable scent.
Flower dimorphism often occurs as a reproductive strategy (called sexual dimorphism) in plants, with one “male” flower morph containing the pollinia and one “female” flower morph containing the stigma. Dimorphorchis rossii and the other four species in the genus Dimorphorchis are rather unusual because both flower morphs contain male and female reproductive structures.
It is not fully understood why these plants produce bisexual dimorphic flowers, but one hypothesis posits that the strong fragrance and bright color of the yellow flowers serve to attract pollinators for the entire inflorescence, including the non-scented white flowers. This hypothesis is grounded in the idea that producing any sort of pollinator attractant (such as a nectar reward or the chemical compounds for floral fragrance) is energetically costly for the plant, and selection will favor plants that achieve the desired result (pollination) with less energy expenditure.
Another idea is that these dimorphic flowers act as pollinator insurance. The diurnally fragrant yellow flowers may entice a daytime pollinator while the odorless, white flowers farther down the dangling inflorescence (a pollinator syndrome indicative of bat pollination) attract a nocturnal pollinator. It has also been speculated that Dimorphorchis’ pendulant inflorescences, which often reach the ground, are a way for a crawling pollinator, such as a beetle, to travel up the flower spike from the forest floor.
At this point, there is no documented evidence for any of these theories. Dimorphorchis rossii (like most orchids) has not been extensively studied and is a prime example of how much there is still to discover about the ecological relationships surrounding these fascinating and rather mysterious specimens.
-Julie Rotramel, Orchids Collection Contractor
This post was originally published on Smithsonian Science.
Non-native plant species pose a significant threat to the natural ecosystems of the United States. Many of these invasive plants are escapees from gardens and landscapes where they were originally planted. Purchased at local nurseries, wholesale suppliers and elsewhere, these plants have the potential of taking over large areas, affecting native plants and animals and negatively changing the ecosystem. In recent years an increase in travel and international trade has rapidly introduced many new non-native species to the United States.
“While not all non-native plants are bad, some imported species are bullies that crowd out native plants and damage the diverse ecosystems that many living things depend on,” said James Gagliardi, a horticulturist with Smithsonian Gardens.
Plants with the highest invasive potential are prolific seeders and vigorous growers which have the ability to adapt well to a variety of conditions. Native species have not evolved alongside these plants and have trouble competing. With few predators and little competition for resources, these new plants can displace native flora, reducing plant diversity until a landscape is no longer able to support longstanding native plant, animal, and insect communities.
Here is James Gagliardi’s list of six plant invaders in the U.S. with suggestions of native stand-ins to plant in your garden:
1. Purple Loosestrife (Lythrum salicaria)
Origin: Europe and temperate Asia
Arrival: Purple loosestrife was introduced to the United States in the early 1800s for ornamental and medicinal uses.
Impact: Now growing invasively in most states, purple loosestrife can become the dominant plant species in wetlands. One plant can produce as many as 2 million wind-dispersed seeds per year and underground stems grow at a rate of 1 foot per year.
Native Alternatives: Blazing star (Liatris spicata), American blue vervain (Verbena hastate) and New York ironweed (Vernonia noveboracensis)
2. Japanese Honeysuckle (Lonicera japonica)
Origin: Eastern Asia
Arrival: One of many invasive varieties of honeysuckle in the United States, Japanese honeysuckle was brought to Long Island, NY, in 1806 for ornamental use and erosion control.
Impact: The plant has become prolific throughout much of the East Coast as it adapts to a wide range of conditions. Japanese honeysuckle is an aggressive vine that smothers, shades and girdles other competing vegetation. Many of the birds eat the fruit of this plant, thereby spreading the honeysuckle’s seeds.
Native Alternatives: Trumpet creeper (Campsis radicans) and coral honeysuckle (Lonicera sempervirens)
3. Japanese Barberry (Berberis thunbergii)
Arrival: Japanese barberry was introduced to the United States in the 1800s as an ornamental. Seeds of Japanese barberry were sent from Russia to the Arnold Arboretum in 1875 as an alternative to European barberry (Berberis vulgaris), which had fallen out of favor as it was a host to Black Rust Stem—a serious fungus effecting cereal crops.
Impact: The shrub has the ability to grow in deep shade and is particularly detrimental to forest lands in the Northeast. The heavily fruiting plant forms dense thicket, crowding out native plants, and its seeds are easily spread by birds.
Native Alternatives: Shrubby St. Johnswort (Hypericum prolificum) and winterberry (Ilex verticillata)
4. Norway Maple (Acer platanoides)
Arrival: The plant explorer John Bartram first introduced the Norway maple to the United States from England in 1756. The widely adaptable tree quickly became popular and was planted in towns as a shade tree and in rural communities.
Impact: The Norway maple displaces native trees and has the potential to dominate a landscape in both the Northeast and Northwest. It displaces native maples like the sugar maple and its dense canopy shades out wildflowers.
Native Alternatives: Sugar maple (Acer saccharum) and red maple (Acer rubrum)
5. English Ivy (Hedera helix)
Arrival: The introduction of English ivy dates back to the early 1700s when European colonists imported the plant as an easy-to-grow evergreen groundcover.
Impact: The planting and sale of English ivy continues in the United States even though it is one on the worst-spread invasive plants in the country due to its ability to handle widespread conditions, particularly on the east and west coasts. English ivy is an aggressive-spreading vine which can slowly kill trees by restricting light. It spreads by vegetative reproduction and by seed, which are consumed and spread by birds.
Native Alternatives: Creeping mint (Meehania cordata), Allegheny spurge (Pachysandra procumbens) and creeping phlox (Phlox stolonifera)
6. Kudzu (Pueraria montana var. lobata)
Origin: China, Japan and the Pacific islands
Arrival: Japan introduced Kudzu to the U.S. at the Philadelphia Centennial Exposition in 1876. It was first promoted as an ornamental plant and later as a forage crop in the Southeast. One million acres of Kudzu were planted in the 1930s and 1940s by the Soil Conservation Service to reduce soil erosion on deforested lands. It was not until the 1950s that it was recognized as an invasive.
Impact: Once established, Kudzu grows at a rate of up to one foot a day and 60 feet annually. This vigorous vine takes over areas in the Southeast by smothering plants and kills trees by adding immense weight and girdling or toppling them.
Native Alternatives: Carolina jessamine (Gelsemium sempervirens) and Virgina creeper (Parthenocissus quinquefolia)
On March 11, 2013, Smithsonian Gardens received accreditation from the American Alliance of Museums (AAM), a designation that confers a high mark of distinction for a museum. Accreditation signifies excellence to the general public as well as to the greater museum community, the public garden community, and other cultural organizations.
Smithsonian Gardens (SG) began the accreditation process in 2007 by undertaking an Institutional Assessment through AAM’s Museum Assessment Program (MAP). The assessment provided an overview of Smithsonian Gardens’ entire management and operational practices and involved three distinct phases—self-study, peer review, and implementation. Using the outcomes of the MAP assessment, Smithsonian Gardens launched an intensive strategic planning process which resulted in an organizational name change (it had formerly been known as Horticulture Services Division) and a refined mission.
Armed with SG’s FY2010-2015 Strategic Plan http://www.gardens.si.edu/about-us/docs/SmithsonianGardens-Plan.pdf , Smithsonian Gardens undertook the AAM accreditation process in 2010. To earn accreditation a museum first must conduct a year of self-study and then host a site visit by a two-person team of peers. AAM’s Accreditation Commission, an autonomous body of museum professionals, considers both the self-study and site visit report to determine whether a museum should receive accreditation.
Of the nation’s 17,500 museums, only 1,000 are currently accredited, and only 3% of the latter are public gardens. In the D.C. metro area only two other public gardens have attained accreditation status: the United States Botanic Garden (www.usbg.gov) and Green Spring Gardens (www.fairfaxcounty.gov/parks/greenspring).
Accreditation recognizes high standards in individual museums and ensures that museums uphold their public trust obligations. Developed and sustained by museum professionals for over 40 years, AAM’s museum accreditation program is the field’s primary vehicle for quality assurance, self-regulation and public accountability.
AAM’s Characteristics of Excellence are the standards by which all museums can and should strive to achieve in ways appropriate to their resources. To best serve their communities, it is essential that museums be committed to institutional improvement and maintaining the highest standards in collections stewardship, governance, institutional planning, ethics, education and interpretation, and risk management. AAM accreditation signifies excellence and accountability to the entire museum community, to outside agencies and to the museum-going public.
For more information about the American Alliance of Museums and its Accreditation Program, including a complete list of accredited museums, please visit www.aam-us.org .
-Sarah Hedean, Horticulturist
In celebration of National Public Gardens Day, join us on Friday for Earth Matters to Smithsonian Gardens – Garden Fest 2013! This year’s Garden Fest is inspired by the National Museum of African Art’s exhibition, Earth Matters: Land as Material and Metaphor in the Arts of Africa.
At Earth Matters to Smithsonian Gardens – Garden Fest 2013!, visitors of all ages can participate in fun and lively activities focused on interacting with the earth. Help create an ephemeral land art installation with materials from the many Smithsonian Gardens with artist Emily C-D, listen to live music, make a seed bomb, journey on an ancient expedition with the help of petrified wood, fossils, amber, and gardens tools, or dance Zumba! Smithsonian Gardens will also hold a plant container design contest, host a photo shoot for our Shutter-Bug Collection on Pinterest, and offer informal workshops on composting. There will be demonstrations highlighting the connection between Smithsonian Gardens’ irrigation plan and the Smithsonian weather station, and learn about the many tomato varieties that are grown in Smithsonian Gardens’ Victory Garden.
Stop by during your lunch break or after work to hear great live music, for a snack or drink at the Castle Café (featuring a special garden menu for the event), view the Earth Matters exhibit in the gardens and at the National Museum of African Art – both open until 7pm – and have some fun in the garden at Garden Fest!
Date: May 10th, 2013
Time: 11 am to 7:00 pm
Location: Enid A. Haupt Garden behind the Smithsonian Castle
Metro: Green/Yellow or Blue/Orange lines to L’Enfant Plaza or Blue/Orange line to Smithsonian