Easter Lilies

With its large trumpet-shaped blooms in pure white color, Lilium longiflorum has become synonymous with Easter. The imagery may be apt for the occasion, but a lot of effort is required to prepare these ephemeral blossoms for a celebration of eternal victory.

While lilies may have long symbolized beauty and purity, the association of this species with Easter is a modern tradition. Easter lilies are native to Japan and in the early 1900s bulbs were imported through Bermuda. The plants eventually made their way to the Oregon/California border with the help of WWI veteran Louis Houghton where they found the perfect climate for thriving. WWII cut off imports from Japan allowing American-produced lilies to take over the domestic market. These plants remain the fourth-most sold potted plant in the industry (behind poinsettias, mums and azaleas). Their market value is more than $35 million annually, and the region between Del Norte County in California to Curry County in Oregon is known as the Easter lily capital of the world. Here 95% of North America’s Easter lilies (>11 million bulbs) are grown.

It may have taken Jesus only three days to rise from the dead, but for the lilies you see blooming today, you must go back three years. On farms in the Easter lily capital of the world where the bulbs are cultivated, Easter lilies have humble beginnings. They are first planted as small bulb leaf or scale. This plant grows for the season and the bulbs are dug up from the ground, graded by size and saved for replanting the following season. This cycle is repeated for another two years. As the plants from these bulbs grow and try to develop flower buds, field workers glide through the fields on special harnesses (so there’s no hours and hours of stooping over) called mechanical creepers and pinch off any buds that form. This is because commercial lily bulb producers want their plants bulking up their bulbs and not expending energy on flower production. Once the flowers are removed, all of the sugar produced by photosynthesis is transported and stored in the underground bulb. This is particularly remarkable in the late summer when the bulbs can have a 1-inch expansion in circumference in just a week or two. Harvesting the bulbs is carefully timed to be just after this growth spurt. At the end of their third growing season, the bulbs have reached commercial grade size and can be packaged and sold to growers that cultivate them for sale as potted plants.

On Easter Sunday these lilies adorn churches and gravestones in splendor worthy of a resurrection celebration. While we may use the flowers as a symbol of the celebration of Christians’ victory over death, there is no everlasting life when it comes to the market value of Easter lilies. Sure, they are perennials and will re-sprout from their bulbs year after year if properly cared for, but they will not naturally bloom at Easter. Of the most popular purchased potted plants, Easter lilies have the shortest buying window of them all- a mere two weeks leading up to Easter when buyers expect plants with blooms and buds ready to burst forth and announce the resurrection. This means that commercial growers must force the plants to bloom in the spring instead of midsummer as is their natural tendency. If they miss their mark on the calendar, they have no commercial value.

How do growers orchestrate this feat of botanical synchronization? I’ve mentioned before on this blog that plants have various ways of keeping time using light (really length of darkness). Plants also have an internal calculator to tally the amount of chilling hours they have received. Together these accounting systems give the plants seasonal information as to when they should burst forth in bloom. After the Easter lily bulbs have been bulked up for three years, growers that prepare them for sale as potted plants ‘force’ them to develop to flowering stage just in time for Easter. This is done by chilling the bulbs near 40 F (but never freezing) for 1000 hours or about 9 weeks during October, November and December. There are a few different ways this can be done before or after potting depending on the facilities available to the grower. Exposure of young plants to long day light conditions in a greenhouse can substitute for up to two weeks of the chilling requirement. This trick is especially useful if Easter is early and it is not possible to achieve full chilling requirements. Keep in mind that the date of Easter can vary by as much as five weeks and Easter lily growers must adjust their calendars accordingly when it comes to plant preparation.

So this Easter, as you celebrate with these lovely lilies, keep in mind that while their flowers may be short-lived, quite a bit of work was invested to ensure they looked just right at just the right time. Continue to care for your plants and the bulbs and the lilies will also rise again- just later on the calendar than when Jesus’ resurrection is celebrated.



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The Flowering Dogwood

Pink dogwood Photo credit: Bridget Campbell

Pink dogwood
Photo credit: Bridget Campbell

Here’s another inspirational plant for the Easter weekend- the flowering dogwood (Cornus florida). The beloved flowers that appear just in time in the spring to remind us of the Cross are not true flowers at all. The white and pink ‘petals’ are actually bracts or modified leaves that surround the clusters of small yellow flowers at the center. This is analogous to poinsettias described previously on this blog.

Legends have linked the dogwood tree to the wood used to make Jesus’ cross, but this association is less literal and more a symbolic reminder of Jesus’ crucifixion. The invariant four-bracts of each blossom resemble the shape of the cross and they each appear to have been pierced at the edges. The inner true dogwood flowers can resemble the thorny cross that adorned Jesus on the cross. Finally, the red berries that ultimately develop there bring to mind Jesus’ blood.

Pink Dogwood Photo credit: Bridget Campbell

Pink Dogwood
Photo credit: Bridget Campbell

Pink dogwood Photo credit: Bridget Campbell

Pink dogwood
Photo credit: Bridget Campbell

Whatever this beautiful botanical may bring to mind, it is definitely worthy of integration in your landscaping plans. This fast-growing medium-size tree is native to North America and thrives in a variety of USDA hardiness zones. Known for its white or pink blossoms in the spring, these trees actually provide beauty year round in different forms. Once spring turns to summer and the blossoms have fluttered away, the foliage colors the landscape a pleasant green. In the fall, the leaves turn red and fruit (drupes) develops into bright crimson clusters. If Good Friday or Easter have failed to inspire you, I should remind you that National Arbor Day is next week, and the flowering dogwood might be a variety to add to your shopping cart or wish list.



*All photos are credit Bridget Campbell, used with permission, all rights reserved.

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A thorn by any other name

When dangerous situations arise for plants, the choice between flight or fight is a simple one. They abide by the stand your ground law and always fight. Such a lifestyle choice means that plants employ a variety of weapons to stave off extinction. Thorns are one of the more obvious botanical defenses. Their appearance is a clear warning not to trample and no herbivore would like a mouthful of sharp spines.

No one will disagree that thorns hurt, but would a thorn by any other name hurt as much? In everyday language usage, we may refer to any sharp plant appendages as thorns, but botanically these sharp protrusions can be thorns, spines or prickles. Their true names are tied to the tissue from which they developed. Thorns are derived from shoot material and are actually branches modified to terminate in a sharp point. Spines are leaves modified to be entirely spike-shaped or barbed along the edges (like holly). Everything else is considered a prickle. So, roses actually have prickles along their stems, not real thorns. Regardless of what term is used, the effect on herbivores and other careless animals that would otherwise trample them is the same.

(A) Thorns and spines are derived from shoots and leaves respectively, and have vascular bundles inside. (B) Prickles (like rose prickles) don’t have vascular bundles inside, so they can be removed more easily. Credit: CASF via Wikipedia

Botanically speaking, Poison’s Bret Michaels was incorrect when he sang “Every rose has its thorn.” I’m willing to give him a pass on accuracy because I’m scared to know how he would’ve rhymed prickle in the subsequent line. Beyond this, modern horticulture is proving him wrong on the entire premise of his song- that all beautiful and good things must have a dark and dangerous side. This may work for the image of a rock star, but plant breeders are diligently trying to disentangle the pretty from the prickly. Some thornless roses are commercially available, but the trait isn’t always stable and thorns can appear when these plants experience certain environmental conditions. For now, the genetics of rose prickles remains a mystery, but eliminating this trait will continue to be the focus of rose breeders and plant scientists.



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Spring-spiration: Plant Color

I’m hosting April’s Berry Go Round blog carnival and the theme is plant color.* So writers of plant science, nature and gardening: whip up something entertaining, informative and colorful (new or old) and submit your links here by the 26th of the month. You can talk about your favorite colors, unusual colors, pigment biosynthesis, how plants use color, how humans have painted new colors onto our favorite plants, color patterns, temporal color changes etc. The canvas is blank and waiting for you. Of course, I’m supportive of posts about all photoautotrophs for those adventurous writers daring to step away from the plant kingdom and delve into algae, cyanobacteria and other microscopic photoautotrophs. Heck, if your post is about fungi, you’ll probably get a pass if it’s colorful enough. I will compile them all together in a link-fest blog carnival by the end of the month.

Spring is definitely here to stay at my latitude, so here are some colorful pictures for inspiration.**

azalea Digitalis Johnny Jump Ups Digitalis Rhododendron bearded iris wisteria iris red clover



*The March Berry Go Round featured posts about Unusual Edibles. Check it out: http://emmacooper.org/blog/march-berry-go-round-unusual-edible-plants

**All photos taken by myself at Afton Villa Gardens in St. Francisville, LA

Palm Sunday

Today is Palm Sunday in the Christian calendar, marking the beginning of Holy Week with Jesus’ return to Jerusalem before his death. Even after one cup of coffee this morning, it is the only Christian holy day I can think of named for a plant. It comes from the fact that palm leaves, a symbol of victory, were used to line the streets as Jesus returned.

Palm fronds from Felix Burton via Wikimedia Commons

Today Christians keep the tradition of processions with palm leaves to mark the spiritual victory celebrated at the end of Holy Week. Notably, these palms are burned after the celebration and the ashes are used in the Ash Wednesday service marking the beginning of Lent. However, palms are not easily found in all climates. In some locales other native plants (willow or live branches) are used as a substitute. Our modern global economy now makes it possible to obtain some kind of palm frond for a more authentic celebration of Palm Sunday.

Unfortunately, unbeknownst to most of Christianity, this tradition is increasingly exploiting the sensitive environment of the rainforest. Xaté palms are prized for their dark green leaves and longevity as cut greenery in floral arrangements. Despite these desirable characteristics, xaté palms are not typically commercially cultivated, but wild-harvested from rainforests in Central America. This practice coupled with the demands for the ideal green filler for the floral industry has resulted in the over-exploitation of this species in its natural habitat. For example, xaté is nearly extinct in Guatemala. In Belize, xaté is still harvested in protected parks because of the logistical difficulties of patrolling these areas. Removal of this one species weakens the complex rainforest ecosystem where it thrives.

Chamaedorea elegans (Bella habit). Location: Maui, Home Depot Nursery Kahului Credit: Forest and Kim Starr

Organizations like Fauna and Flora International are working on initiatives to protect xaté palms in their natural habitats. They are also supporting efforts to develop techniques for effectively growing the palms as a specialty crop because it is a valuable horticulture product for the people of Central America.

So today and other days when you’re using floral arrangements to “Say it with flowers,” try to track the source of your palms. Loss of a beautiful and diversity-rich ecosystem for the sake of a filler or exotic component of a ceremony is no triumph at all.




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Azaleas Announce Spring (and maybe summer and fall)


Azalea after April shower

VID00704In more northerly latitudes, spring may still be sputtering to start with all varieties of showers this April. However, south Louisiana already has plenty of flowers announcing the arrival of spring. One staple of southern landscapes is the azalea, and during the first true warm stretch of spring these plants burst forth in bloom in outrageous splendor that absolutely cannot be ignored.

They seem to shout, “I dare you to tell us that spring isn’t here! We. Are. Spring.” Honestly, I’m not one to argue with them, especially some of the older unpruned specimens that could be their own Rose Bowl Parade float.

George Lindley Tabor Azalea at LSU

George Lindley Tabor Azalea at LSU

While azaleas can be found in just about every private yard in Louisiana, the Baton Rouge campus of LSU offers some real azalea beauty this time of year. I think the LSU Alma Mater must have been written some time other than spring because it makes no mention at all of the azaleas. It begins, “Where stately oaks and broad magnolias shade inspiring halls…” leading one to conjure imagery of a place solemn and reserved for the pursuit of knowledge. The trees are impressive, but in the spring, the campus is decked out in all shades of pink and white.

Azaleas under stately oaks at LSU

Azaleas under stately oaks at LSU

1374375680Nothing about them is modest or reserved in the spring. But as spring turns to summer, they resign themselves to pleasant evergreen foliage for the rest of the year. They are truly the beauty pageant belles of Southern gardens, sparkling for a brief moment in the spotlight before settling down in the suburbs with three kids and a minivan. Fortunately for us, horticulturists and azalea breeders have been working on just this problem; the azaleas, that is, Miss Alabama 2003 will have to turn to someone else to renew her beauty. More specifically, breeders have been identifying and selecting for plants that bloom again in the summer and fall. The most successful of these are the Encore azaleas invented by Robert “Buddy” Lee in Independence, LA. We may not understand how at the molecular level these varieties have been ‘tricked’ into blooming multiple times each year, but I’m sure it has something to do with the plant’s internal clock that keeps track of the seasons and coordinates the timing of their reproduction. Nevertheless, gardeners sure don’t seem to care as long as they can continue to enjoy their favorite flowers. For more information about caring for azaleas in your southern garden check out the links below from the LSU AgCenter and Encore Azaleas.




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^^The most awesome domain name on the interwebz!




Adamantium, for plants!

Researchers have basically created the plant equivalent of Wolverine

Researchers have basically created the plant equivalent of Wolverine

One of the goals of photosynthesis research is to improve plants’ productivity to a level adequate for human food and energy needs. As of now, plants are currently doing a good enough job to reproduce themselves and mostly sustain our biosphere, but we would still like to kick this up a notch. Scientists are using a variety of tools to tackle this problem. The most notable is using genetics- either by breeding new varieties or genetically engineering new traits by manipulating specific genes sometimes between different organisms. Today’s post features another type of engineering to improve plants ability to photosynthesize- nanotechnology.

Researchers at MIT report that plant chloroplasts can be infused with carbon nanotubes to impart increased photosynthetic capacity (as much as 49% greater than unaltered chloroplasts and 30% in whole plants). Much like the X-Men character Wolverine was infused with the metal alloy adamantium to render his skeleton indestructible and give him those awesome retractable claws, plant chloroplasts can be infused with special materials to give them what amounts to photosynthetic superpowers. No, they didn’t use adamantium. The material used in their study was carbon nanotubes fused to cerium oxide nanoparticles aka nanoceria.*

You may be wondering to yourself, “What exactly are photosynthetic superpowers?”**

The nanoceria are able to absorb infrared light, which no native plant pigments can do. Plant pigments like chlorophylls and carotenoids do a good job of covering the visible light spectrum, but this is only half of the incident solar energy beaming down on them all day. The researchers in this study conclude that the boost in photosynthetic capacity is in part due to the fact that the nanotubes absorb light energy beyond the visible range and can then transfer this energy to the photosynthetic machinery. In this way, the nanotubes are acting like an antenna- a giant antenna that doesn’t just boost the signals you’re already getting, but allows access to a whole set of new premium channels.

The nanotubes have a couple of other advantageous side effects as well. The cerium oxide nanoparticles are quite effective radical oxygen species (ROS) scavengers. Remember when I told you photosynthetic organisms have a complicated relationship with light? They need enough of it to live, but too much can be extremely damaging. This is why blasting plants with bright light at all times isn’t necessarily the best way of improving their growth and productivity. Likewise, improving their ability to capture light can also be dangerous. This is all due to the fact that overloading the photosynthetic circuitry with too many electrons can start to generate ROS which in turn irreversibly damage proteins, pigments and DNA they encounter. Since the nanoceria are quite good at scavenging or capturing and inactivating ROS, they also boost photosynthesis by helping out plants’ innate systems for dealing with this problem. Again, like Wolverine, plants have some level of ‘healing powers’ when it comes to dealing with light, but the nanotubes help kick it up a notch. Wolverine’s adamantium doesn’t really help with his healing powers, but coating his skeleton with it means it doesn’t get broken as easily and he doesn’t have to use his healing powers to mend broken bones. In the same way, the nanoceria prevent some damage before it happens so the plants don’t have to waste their resources on repairing damage caused by ROS.

In true superhero style, the nanotube-infused chloroplasts’ powers don’t stop there. They also confer the ability to detect certain chemicals in the environment. Yes, just like Wolverine has heightened senses (if he twitches is nose, he’s knows you’re there!), chloroplasts containing nanotubes do too. Different types of nanoparticles have been developed to detect toxins and pollutants like nitric oxide, sarin gas, and TNT. Integrating this technology into a photosynthetic organism may allow plants to become stealthy biodetectors of these chemicals. No longer would they be merely scenery, but solar-powered secret agents (green-ops?) with skills no training could ever provide.***

These super powers may not be indestructible retractable claws, but it’s a good start down the path to lots of useful applications.

Conclusion: Plants infused with nanoceria definitely qualify as super photosynthesizers, but we still have some work to do to put this into useful practice beyond the lab.

How do nanoparticles and enhanced photosynthesis affect plants over their entire lifespan vs. short experiments in the lab? Does this kind of boost in the light reactions translate into an increase in biomass? Sure, the light reactions could always use some help when sunlight is less than its brightest, but the real rate-limiting pathway is the dark reactions. (I’m looking at you Rubisco!).

How can this technology be translated into field agriculture to boost productivity of crops? Is it worth it? It’s not like you can propagate the nanotubes biologically, but who knows, maybe in the future tractors will be outfitted with attachments to infuse or spray seedlings with nanoparticles. In terms of calculating potential for improving plant productivity, photosynthetic energy conversion remains a variable in the equation that has yet to be thoroughly tapped when it comes to improving crop plants. Using carbon nanotubes to extend the spectrum of useful light into the infrared would definitely help plants breakthrough some yield ceilings we are seeing.

How can we turn our scenery into useful biosensors for pollutants? What kinds of chemicals can they detect and how can that be cheaply and easily measured? Sure, everyone and their grandma has a satellite and a drone these days, but are we really going to have to laser scan our environment every hour? How about a nice color change or wi-fi signal that NORAD can detect?

Speaking of wi-fi, why can’t we engineer plants with nanotechnology that allows them to have other superpowers, like transmitting wi-fi signals? Solar-powered free internet anywhere! Finally, getting plants to release something useful besides oxygen****, and it would go a long way to keep me from going over my monthly data plan limits.

These are all questions and exciting possibilities that will keep photosynthesis researchers like the Strano lab busy for years to come.


*IMHO, ‘nanoceria’ is itself a name worthy of comic book lore. Maybe DC Comics can do a series where Swamp Thing is infused with nanoceria boosting his plant-like powers.

** You must be new here. Welcome.

***K-9 units may be relegated to history. SWAT, move over for SWNTs. (You’ll get it if you read the paper).

****It’s important to me that you catch the sarcasm in that phrase. If you’ve been breathing today, thank a photosynthetic organism.

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(paywall) http://www.nature.com/nmat/journal/vaop/ncurrent/full/nmat3890.html