Spring is coming…and soon herbaceous perennials will poking their leaves up through the mulch:
Obviously as leaves first emerge they’ll be vertically oriented – but these ones have remained vertical days after emerging. Eventually they’ll become horizontal. But today’s question is – what’s the advantage in remaining vertical? And what’s this phenomenon called?
Answer on Monday – have a nice weekend!
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Linda Chalker-Scott
Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets.
Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019).
In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award.
"The Garden Professors" Facebook page - www.facebook.com/TheGardenProfessors
"The Garden Professors" Facebook group - www.facebook.com/groups/GardenProfessors
Books: http://www.sustainablelandscapesandgardens.com
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Awesome question.
I have never thought about the fact that leaves emerge vertically first and that there might actually be a purpose behind it. Or that there would be a specific name for this.
I would venture to guess that by emerging vertically the leaves have more strength to push through debris to get to the sun. But what causes the leaves to then go horizontally?
I’m looking forward to Monday to find out the answers!
My gut tells me that the leaves remain vertical to optimize photosynthesis in a cool environment and perhaps to help prevent freezing because of less surface area exposed to collecting moisture. I looked around a bit in my books and couldn’t come up with the name for this. Thank you, this is so much fun. I can’t wait for other comments and of course the answers.
I don’t know as I was ever taught about this. My first thought was it is a protective mechanism to give the leaves time to adjust to the environment – harden off – so to speak.
I am interested to hear what this phenomenon is called.
I’d say that because the winter sun is at a lower angle they present a larger surface area to the sun.
Saxifraga!!!
So cute!
Once the weather warms up, I may not get around to solving these puzzlers. I decided it must be a tropism of some sort and a quick search landed me at a really cool site called “Plants in Motion” from the Indiana University Biology Department.
http://plantsinmotion.bio.indiana.edu/plantmotion/starthere.html
I think the phenomenon in your puzzler is likely related to photomorphogenisis, but I will have to tough it out over the weekend before finding out for sure.
What a timely question! I am currently reading Botany for Gardeners by Brian Capone. The question is sure to help me understand what I’m reading. If I can come to a conclusion, I’ll post it here.
My guess is that plants that emerge with a vertical orientation are usually growing in a shady environment. As a result they are stretching for more light… plants shielded from light tended to grow upright at a faster pace to garner more light, and in turn very quickly become larger until they have reached a balance where they have enough light and can then slow down and let their leaves become horizontal. However, I do not have a name for this process. How about “verticalization?”
I would venture to guess that the reasoning behind the vertical orientation has a lot to do with the potential for late snowfall. If the leaves are vertical they stand less chance of being buried under a light snow and having the cells freeze. I can’t recall ever hearing a term for this behavior though.