Botany word of the week.*

Marcescence

This is the retention of the dead and dry leaves (and sometimes other parts such as fruit or seed pods) on some deciduous trees through winter.  Persistence, or as I like to think of it: a relentless lingering, somewhat along the lines of my cat’s queries for elevenses, twelveses, oneses, twoses (you get the idea).  Some trees seem to exhibit marcesence as  a trait – oaks are apparently one of them, although our climate isn’t mild enough for most Quercus spp. so I can’t perform a decent study on multiple varieties.  I did take a wander past the row of bur oaks (Q. macrocarpa) that grow near the train station in my neighbourhood, and while there were a few single leaves straggling on the branches, the trees were pretty much completely bare.  But we have to count that as an insufficiently representative sample (which, incidentally, also seems to be my cat’s views on the amount of food I give her).

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There are several theories on what causes marcescence, and what purpose it serves.  I believe in the case of this elm tree (and others like it in our city), the early frosts and severe cold we received back in September led to a failure of the formation of the abscission zone.  (This is an area of separation created by the natural weakening of cell walls between the petiole and the leaf.  While deciduous trees abscise in autumn, conifers do it pretty much all the time.  Another big difference is that deciduous trees normally fling everything off and conifers are, well, waaaaaaay more reserved). The leaves in my photo basically died on the spot and the tree wasn’t quite ready for that to happen. The wind took most of them off but some are still hanging around, waiting for spring like the rest of us.

Some researchers speculate that marcescence is a defense mechanism for the tree, protecting it from the munching of herbivorous predators such as moose and deer (who are going to eat fresh, tender young branch tips over icky dry foliage every time.  You can’t blame them, really).  Another idea is that the dry leaves act like little windproof shawls for the leaf buds, protecting them from winter desiccation.  Perhaps.  Still another thought is that the trees are deliberately generating their own mulch, dropping it at just the right time – spring, not autumn – for maximum moisture retention and as a source of nutrients.  Far-fetched?  Maybe, maybe not.

So what happens in the spring, when the buds of the new leaves break?  The marcescent leaves may remain on the tree, still waiting for a really strong wind to snap them off, or they may be pushed off the tree by the new growth, in which case they are instantly sucked up into a magical vortex so that you never have to rake them up.  

Then again, there are never any guarantees when it comes to magic, so have that rake handy, just in case.

Sources:
Finley, Jim. “Winter Leaves that Hang On.” PennState College of Agricultural Sciences. 2012. https://ecosystems.psu.edu/research/centers/private-forests/news/2012/winter-leaves-that-hang-on.
Gast, Richard. “Marcescence: An Ecological Mystery.” Adirondack Almanack. November 19, 2017. https://www.adirondackalmanack.com/2017/11/marcescence-ecological-mystery.html.

*To be completely truthful, I’m not sure which specific day of the week the Botany Word of the Week will be posted.  Or that it will actually be posted weekly.  It may kind of float around and periodically pop up and surprise you.  Hopefully that’s okay.  

Calgary snapshot: Fish Creek Provincial Park.

Fish Creek Provincial Park is Canada’s second largest urban park (Rouge National Urban Park in Toronto is tops in the country).  Fish Creek features 80 kilometres (50 miles) of trails, the tiniest fraction of which I accomplished this morning.  But what a lovely start to the day!

Air plants.

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So, it keeps snowing here and our cat eats pretty much all my stuff, including my houseplants.  (Of course, she leaves all my hubby’s possessions alone – his newspaper apparently doesn’t taste nearly as delicious as my research notes or my library books).

My solution?  Grow air plants. You do this indoors so the snow doesn’t matter a whit. The air plants I can afford are tiny.  They don’t need soil (soil, another thing Smudge thinks is seriously PAWsome – um, did I just write that?!). I can put them in jars and other decorative containers and hang or place them out of cat reach, which is an actual zone in the house with a fixed length and breadth that has taken me a year to get a solid grasp of.

Anyway, now I fear I may want to collect the darn things.  (The air plants, not cats.  Smudge is ALL the cat).*  I accidentally went to the garden centre the other day (had to take two trains and walk three blocks uphill both ways in the blasting wind) and came home with yet another air plant.  I would have bought the large red one as well (it was RED!) except it was priced at the equivalent of a few hours of my salary and I thought maybe my hubby might be a bit grumpy with me.  So I’m saving up for it.  I’ll tell him it’s cheaper than a new car, and he cannot argue with that.  I just wish they would label the silly things so I would know the cultivars. Tillandsia doesn’t help me; I knew that already.  😉  And I BEG and PLEAD that the ones in some of the grocery stores would be treated with more dignity and not GLUED into their containers.   They cannot be watered properly and they’ll keel over at some point from neglect.  Air plants are not made of plastic.  They are actually alive and need some care.

While meandering through reams of information about air plants for an article I recently wrote, I came across some fantastic titles at the library – if you are interested in this captivating genus, track down Air Plant Care and Design by Ryan and Meriel Lesseig and Zenaida Sengo’s Air Plants.  The Lesseig book, in particular, is brilliant, impeccably researched and extremely detailed.

Do you grow air plants?  

Do you have an indoor cat (or cats)?  What creative solutions did you come up with to maintain your houseplants in the same space as your curious feline?

*Pic here. ♥

Garden snapshot: Parsley.

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When asked about “seriously hardy and reliable” herbs for our climate, parsley is always a ready answer. I grew both Italian (flat leaf, seen here) and French (curly leaf) this year – I love them both and can never decide which one is my favourite. I harvested the leaves from all of my plants in late September and we’ve had two snowstorms and a couple of weeks of hard overnight frosts since then, and they are still merrily growing away. If the weather holds, I will get another handful of fresh leaves yet before winter settles in.  Sweet!  I won’t dig these up to overwinter as I have no room indoors (and they won’t last five minutes with our cat)…but I’ve had parsley overwinter inground in the past so perhaps it will be a gift that keeps on giving next year.

Another type of parsley I’ve grown in the past is root (Hamburg) parsley – our growing season is so short in Calgary that I don’t get really large roots from the plants, but I’ve had decent success with them each year I’ve put them in.  And, as a bonus, you can eat the tops as well.  A hugely versatile plant!

Is parsley a favourite of yours, as well?

End of the growing season….

Had a chuckle when I saw this rhubarb leaf while cleaning up my plot at the community garden…reminded me a bit of a certain Dali painting.

Perhaps I need some more sleep.  😉

Larch trees in autumn.

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It’s easy to see why I adore larch trees, particularly in autumn.

And yes, that is snow in the background! We’ve had two significant snow storms in Calgary since September 29th. The first one dumped 31 centimetres (12.2 inches) of the white stuff on us (which, amazingly, wasn’t a record, although it was close).  More snow is expected early next week so I had better try to get my garlic planted in the next few days!