Allium Fever

Ornamental onions are hot patooties.  From big, bold, purple globes to small pink half-moons, there is no end to ornamental onion-y goodness out there with 30+ species and cultivars in the trade.  There’s no substitute for ornamental onions in regards to architectural drama – the perfect geometric foil to wispy grasses, floral spikes, and umpteen daisy-thingies.  The seed heads from the sturdier species will persist and add interest to autumn and winter perennialscapes (not sure if that’s a word).

Art-of-Gardening-COVER-3D-1
Not one but TWO cultivars of Allium on the cover of the fabulous new Chanticleer book…

All are members of the Allium genus, just like those onions sprouting in your kitchen counter veg basket – hence the deer- and small mammal- resistance factor.  However…there are some issues.

  • Can be short-lived.  I have first-hand experience with this – plant, enjoy for a year or two, then…where did they go?
  • Bloom time is rather vaguely defined.  Most catalogs list “early summer” or “late spring” for most cultivars.  But if you want continuous purple orbs, what’s the order of bloom?
  • Can be expensive. Bulbs for some of the mammoth “softball” sizes will set you back $5-$7 each (the bulbs themselves are huge).  This is of particular concern due to the first item.
  • Foliage failure.  For some of the largest species and cultivars, the foliage starts to die back around (or even before) bloom time.  Not a lot of time to put the necessary energy back into that big honkin’ bulb.

We already have a multi-year lily perennialization trial going in conjunction with Cornell and some other institutions.  I thought I might try the same thing with Allium.

Student worker Lauren, after a long day of taking data on a gazillion lilies.
Student worker Lauren, after a long day of taking data on a gazillion lilies.

Unfortunately, I had this bright idea in November – well into the bulb-ordering season.  I tried to compile as complete an inventory as I could, ordering from several vendors.  Ended up with 28 species and cultivars – as much as the space prepared (check out that nice soil!)  could hold, at our urban horticulture center near campus (Virginia Tech is in Blacksburg, USDA Zone 6, about 2000′).  We put five or seven bulbs (depending on size) in each plot, and replicated the whole thing three times.

Ready to plant!
Ready to plant!

We’ll take data over the next three years on time of emergence, bloom time and duration, foliage duration (have a nifty chlorophyll meter that can help quantify that), some growth measurements, and perennial tendencies (or not).  My hope is to end up with a really specific chronology of bloom times plus life expectancy.  Yes, this was just a patented Holly wild hair; luckily I had some general funds to cover it. But I do think our little onion project will be of interest to more than a few folks, whether professional landscape designers or home gardeners.  I know I’m excited to see the results ($30 for five bulbs – yeek)!

 

 

Upside-down growing

I was poking through old photos and came across this oddity:upsidedowntrees

What you are looking at is Japanese maples (Acer palmatum) being grown hanging upside down. I saw this year ago at a nursery in Japan. (You are also probably looking at a disaster of girdling roots in those tiny plastic pots, but that’s another topic) When I asked about them, I was told that they are weeping forms, and grown this way temporarily before being planted in the ground right-side up.
Looking at the image, it makes me think that the particular variety grown here might have a mutation that makes them negatively gravitropic, and so respond to the pull of gravity in the opposite way a normal plant would. (For more on that see my earlier post on gravitropism in corn) Growing them upside down would allow them to produce a fairly normal branching pattern, and then once plants, new growth would, presumably, cascade down from the established trunk and stem.
Anyway. That’s your oddity for the day.
Joseph Tychonievich

Love notes of genetics and physiology for Valentine’s Day

A St. Valentine meme compliments of my "friend" the self-styled Rev. Apostle, and Bishop to the Stars, Joel L. Watts.
A St. Valentine meme compliments of my “friend” the self-styled Rev. Apostle, and Bishop to the Stars, Joel L. Watts.

Ahhh….’Tis the time of year when we celebrate romantic love in homage to a 3rd Century priest who came up a head short for performing unsanctioned Christian weddings.  (It is also of note that St. Valentine, or Valentinius as his friends called him, is the patron saint of bee keepers but, strangely, not of birds, flowers, or trees).

In celebration, many suitors, partners, spouses, fling-seekers, and woo-wishers will flock to florists, grocery floral counters, and even gas stations to purchase flowers, namely roses, that have likewise been beheaded.

Those roses, with all of their tightly wound petals, look nothing wild-type roses. Modern roses are the product of many centuries of breeding that started independently in China and the Mediterranean region.

So if the wild-type rose has a single row of five petals, how do breeders get all of those extra petals?  They can just come from nowhere, you know.

The simple answer is that tissue that turns into stamens in the wild-type flower are converted to petal tissue.  While early (and even contemporary) plant breeders may not understand the mechanism responsible for the doubling (gene expression), research is showing that the same gene is responsible for the doubling in both the Chinese and Mediterranean set of species/subspecies.

In a nutshell, what happens is that the different regions of the flower – sepals, petals, stamens, carpel – develop in response to the expression of a set of genes.  It isn’t just the genes acting alone, though; it is their interaction in the tissues that makes the difference.  These genes are grouped by the floral part they affect and are grouped as A-Function, B-Function, C-Function, and E-Function.

If you want to learn a whole lot more about it than I can ‘splain (it has been a few years since my last plant physiology class), this paper thoroughly explains the gene expression and evolution of the flower.  Their figure depicting the flower model is informative, yet simple.  I’ve included it (and its accompanying caption) below.

The ABCE model of floral organ identity. Sepals are produced where A function acts alone, petals where A and B functions overlap, stamens where B and C functions combine, and carpels where C function acts alone. In the eudicot genetic model Arabidopsis thaliana, APETALA1 (AP1) and APETALA2 (AP2) are the A-function genes, APETALA3 (AP3) and PISTILLATA (PI) together specify B function, C function is specified by AGAMOUS (AG), and multiple SEPALLATA genes provide E function
The ABCE model of floral organ identity. Sepals are produced where A function acts alone, petals where A and B functions overlap, stamens where B and C functions combine, and carpels where C function acts alone. In the eudicot genetic model Arabidopsis thaliana, APETALA1 (AP1) and APETALA2 (AP2) are the A-function genes, APETALA3 (AP3) and PISTILLATA (PI) together specify B function, C function is specified by AGAMOUS (AG), and multiple SEPALLATA genes provide E function.  http://www.pnas.org/content/107/52/22570

 

In the paper “Tinkering with the C-Function: A Molecular Frame for the Selection of Double Flowers in Cultivated Roses” researchers show that in lines from both regions of the world produced double flowers as a result in a reduction of expression of the C-Function gene AGAMOUS (RhAG) leads to double flowers.  In Arabidopsis (every plant lab bench jockey’s favorite model plant), this reduction shifts expression of the A-Function genes toward the center of the plant, turning stamens into petals and carpels into sepals.

Now, one question I get from time to time is “why don’t these roses smell like the old-fashioned roses?”  One answer is that as we breed for looks, we are breeding out genes responsible for scent oil production.  So Shakespeare was actually wrong when he said that “a rose by any other name would smell as sweet.”  That isn’t true these days.

So, I wish you a perfectly lovely Valentine’s Day, no matter how you celebrate. Just remember to whisper sweet nothings of floral gene expressions in your sweetheart’s ear.  And remember to stop and smell the roses – if it is a variety that has a decent scent.

Founding GP under fire… for doing her job.

Susan Harris over at Garden Rant has done a terrific write up of all the details, so I’ll be brief here: Linda Chalker-Scott, the founder and fearless leader of The Garden Professors, is facing possible termination from her job at Washington State because she’s doing exactly what it says in her job description — extension, providing gardening information to the public — instead of bringing in big research grants. Universities love grants because they means money, and educating the public doesn’t. And money, more often than not, trumps little details like actual job descriptions and the educational missions of public land-grant universities.

Again, for the all the details, please see the Garden Rant post, including info on how to help stop this from happening.