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How was the modern poinsettia created by an infection?

By Chelsie Vandaveer

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KIller Pick: Kaleidoscope Dutch Dinner Plate Dahlia Collection, Barlow Columbine—>Click here.

Royal Red Hydrangea, Variegated Weigela, Three-Seasons of Beauty Garden—>Click here.

In Mexico, the poinsettia (Euphorbia pulcherrima) becomes a large shrub. With annual sales around 300 million dollars (US), the poinsettia has become a familiar plant. But the modern poinsettia would seem strange to the Aztecs who revered it.

The cultivation of poinsettias in the U.S. and Europe began after 1825. The plants were leggy with few heads of red bracts (restricted-branching). In 1923, Ecke Nursery in California had a poinsettia cultivar with numerous short branches (free-branching) that would bear many heads of red bracts. The new poinsettia came from the old poinsettia, but there was a drastic change in the morphology (the form of the plant).

How did the poinsettia get it's name? Click link to find out.

Poinsettia (Euphorbia pulcherrima) Plant of the Week 12/24/2001
Poinsettia Holiday Desktop

About the same time as the free-branching poinsettias were introduced, poinsettia mosaic virus (PnMV) was found infecting all of the free-branching and many of the restricted-branching poinsettias. Was the virus the cause of the free-branching and if so, why didn't the infected restricted-branching poinsettias start forming more branches? Was something else happening to the plants?

Nurserymen noticed several things about PnMV. If poinsettia cuttings were heat-treated the virus was not passed to the new plant. Meristem (undifferentiated actively growing tips) tissue culture also did not have the virus when taken from an infected plant. But both of these reverted to a restricted-branching habit. And someone noticed that periwinkle (Catharanthus roseus) did not catch PnMV when in the vicinity of infected poinsettias.

Dodders (Cuscuta spp.) are parasites in the morning glory family. Dodder also acts as a disease vector between susceptible plants. Using dodder as a bridge between infected free-branching poinsettias and periwinkles, plant scientists at Ball FloraPlant and the USDA hoped to pass to the periwinkles any other causative agent knowing the periwinkles were immune to PnMV.

After a few months, the periwinkles began growing bushy. The causative agent was a phytoplasma. Phytoplasmas are bacteria-like organisms that lack a cell wall and live only in the phloem tissue of plants and a few insects. They change the way a plant grows usually to the detriment of the plant, but not always. Poinsettias could now be infected with the phytoplasma from the periwinkle and become free-branching without catching the poinsettia mosaic virus.

Colorado State University Extension Service has a photograph and an excellent article about dodder (Cuscuta spp.). To view the photograph and learn more about dodder, click on the link:

http://www.coopext.colostate.edu/TRA/dodder.html

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Unique Professionally Designed Gardens

Springhill Nursery®

Spring Hill Nursery has unique gardens professionally designed by experts to take the guesswork out of gardening. Whether you are looking for a three season garden, foundation garden, or a garden to attract hummingbirds and butterflies, Spring Hill Nursery has created a step-by-step design just for you. Click here - $20 off your first order at Spring Hill Nursery!

Kaleidoscope Dutch Dinner Plate Dahlia Collection

Breck's Bulbs®

These exotic giant bicolour Dahlias would steal the show in any garden! And you will love them in your garden. Each #1 clump produces huge, vibrant 5-9" flowers on a plant that grows 2-4' tall. The blooms are magical, like giant, glowing garden torches waving in the breeze. We've selected 4 of the most spectacular hybrid Dahlias ever grown in Holland for Breck's Kaleidoscope Dinner Plate Dahlia Collection.

Plant them after the danger of frost has passed. These giant Dinner Plate Dahlias celebrate long, warm days in the sun, well-drained soil and protection from strong winds. They begn flowering in early summer and keep on blooming well into the fall - until the lingering frosts tell you winter is on its way. Lift in fall for winter storage. In spring, divide the multiplying tubers for additional plantings.

Each Collection includes 2 each of the following:

Pretty in Pink - Huge fantastic pastel flowers are 5-7" across. Immense size and prolific blooming make this one of the finest Dahlis. Grows 3-4' tall.
Seattle - Incredible 7-9" golden yellow blooms with contrasting white tips are more intense than sunshine. Grows 2.5 - 3' tall.
Procyon - Radiant shades of red grace the tips of vibrant yellow petals. Bold and colour-fast for months. Grows 3 - 3.5' tall.
Mystery Day - Big, skyrocket purple and white blooms make a big impact in your garden. The 7" flowers are glorious all season long! Grows 3 - 4' tall.
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Barlow Columbine Mix

Breck's Bulbs®

A must for every flower arranger! Masses of nodding flowers in red, blue, pink and black hang gracefully from tall stems complemented by handsome, lobed leaves. Each uniquely shaped bloom is comprised of layer upon layer of petals, much like a dahlia. Carefree plants return year after year, adding old-fashioned charm to cottage gardens, traditional borders and flower arrangement. Blooms can last 3 to 4 weeks! Space #1 plants 2-3' apart in sun or partial shade. Grows 34-36" and blooms mid to late spring. Zones 3-9. Aquilegia vulgaris Free $25 off any order of $50 or more at Brecks Bulbs

Royal Red Hydrangea

Springhill Nursery®

Hydrangea hortensis compacta - Blazing 4" flower heads decorate trouble-free shade-loving shrubs that grow 3-6' high. Plant 4' apart.

Add luster to your landscape with this Royal Red Hydrangea shrub. Hydrangeas are among the world's most beautiful and carefree shrubs. There is nothing as stunning as hydrangeas blooming en masse to bring life to a shady area, and they thrive in sunny conditions as well.

The Royal Red Hydrangea not only makes a dramatic hedge, but also is excellent as solo specimens. The splendid floral clusters enliven the plants for months on end, from midsummer to early fall. In more severe climates, hydrangeas enjoy some protection, making them ideal for planting against walls or foundations. Flower heads remain attractive into winter and are great in dried arrangements. Shipped in 4" pot. Deer tend to avoid. Zone 5 to 9

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Variegated Weigela

Springhill Nursery®

Bird lovers, this flowering shrub is for you! Gracefully arching shrub boasts densely clustered, 1" funnel-shaped pink blooms which are especially attractive to hummingbirds. Flowering lasts from late spring into fall. The foliage is as distinctive as the pink flowers; its oval leaves are variegated - green edged with creamy white.

This outstanding shrub will be a charming addition to any home environment, but is especially well-suited to withstand city conditions; and its compact size (4-6' high with a 5' spread) fits most urban landscapes.

Hardy. Pest and disease resistant. Requires only a minimum of care to yield years of beauty. Superb as a solo specimen, or plant two or more together to create a colorful hedge. Space plants 5' apart. Shipped in 4" pots. Zone 4 to 9

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Three-Seasons of Beauty Garden

Springhill Nursery®

We asked our garden experts at Spring Hill to take a typical 12'x12' bed and show how it could be planted with perennials and shrubs to provide a continuous display of floral and foliage color from spring, all through summer, and until the hard frosts of fall-and here's the impressive result! It's an easy-to-adapt idea that will give any area of approximately 140 sq. ft. (10'x14') around your home a truly professional look-with a minimum of work and without a serious drain on your pocketbook.

This spectacular parade of color starts in spring and continues all through summer and into the fall. The Fantasia Mums are not like regular Cushion Mums you buy from local garden centers, which die off after flowering. The Fantasia Mums are extra free-flowering and sufficiently hardy to come back again each year. The shrubs in this selection are also special-a Variegated Weigela for color that starts in spring and continues all season, a Forever Pink Dwarf Hydrangea for summer, and a Dwarf Burning Bush that colors-up in autumn.

SPRING: This Three-Seasons Garden doesn't wait for summer to produce beautiful color. Blooming begins in spring with the gorgeous pink blossoms of Variegated Weigela, followed by Poker Primrose and Pink Dwarf Bleeding Heart.

SUMMER: All summer long, your Three-Seasons Garden will be alive with the colorful blooms of Daylilies, Black Eyed Susans, Pink Mist Scabiosa, Orange Glory Flowers, Blue Butterfly Delphinium and Forever Pink Dwarf Hydrangea, adding their floral beauty to the interesting assortment of foliage textures which will enhance any setting.

FALL: The color parade of your Three-Seasons Garden doesn't stop when tinges of fall fill the air. Three different varieties of Fantasia Mums will provide multitudes of colorful blooms week after week all autumn long, augmented by the dramatic red foliage of your Dwarf Burning Bush.

1 Garden includes 30 prime quality perennials.

Click here for $20 off your first order at Spring Hill Nursery! [More Gardens...]