Why Crocus Flowers Open for the Sun
So quickly, the Snowdrops (Galanthus nivalis) have passed their peak, but I cannot be sad. Their flowers will last a while longer, and in the meantime the Crocuses are stepping up to the plate.
In my garden, these are mainly Crocus tommasinianus, or Tommy Crocuses. Tommies have a limited color range (mainly purple), but many consider them more resistant to rabbits and other evil garden vermin. Certainly, that has been my experience.
I have a strong childhood memory of a patch of Crocuses near my parents’ house. Every March I would look for them on the way to school. When they bloomed I always felt a little jolt of happiness. And so I have a soft spot for Crocuses to this day.
Anyhow, yesterday Judy went out to take pictures of the garden, including the Crocuses. It was a day of mixed clouds and sun, and I was a little anxious that Judy catch these flowers while the sun shone, as they are likely to close up when it is overcast.
Which made me wonder: why and how is it that Crocuses (and tulips and many other flowers) close up in the absence of light?
A little internet research revealed an answer, or at least a scientific name for the phenomenon: nyctinasty. Nyctinastic flowers close up in the dark either by pumping water out of cells at the base of the petals, or by growing new cells on the outside of the base of the petals, which forces them shut. To open, they grow cells on the inside.
To be honest, it’s not completely clear to me how this mechanism works, but I’m willing to believe that it does.
It’s impossible to know for certain why flowers engage in this behavior (isn’t it odd to think of flowers having behaviors?). The most popular theory is that nyctinasty evolved to protect pollen from dew or rain. Apparently wet pollen is not as attractive to pollinators and/or is not as conducive to pollination.
The other thing that I wonder about: couldn’t they come up with a better name for this phenomenon than nyctinasty? It sounds like something very unpleasant. More evidence that botanists need to hire marketing consultants to review all their naming decisions.
gardeninacity 
Such pretty flowers.
Indeed.
I so agree that botanists need a marketing consultant for naming plants. Your crocuses look so nice in their little clumps. They are happy little flowers. I just wish they lasted longer.
Me too. Fortunately others step forward to provide continuing color.
Ha! I learned a new word – thank you, Jason! (Even though my pronunciation is probably completely wrong…) And, I very much enjoyed seeing your Tommies – I’m a crocus lover too. Especially the dark purple ones. 🙂
The good news is I have no idea what the correct pronunciation would be. Glad you are a fellow crocusphile (that is probably not a word, but you know what I mean).
I believe the proper term is “croconut”
What a strange word. Many flowers do this, and crocus right now is fascinating to watch. especially when the bees come to visit them. Yours are a lovely colour. I have them in all colours.
I haven’t seen any bees yet, I hope they emerge soon.
Jason do you divide your crocuses and spread them out? I wonder if they’re not a bit like daffodils if they are crowded they stop blooming so much?
I never have divided them … that may in fact be the best practice with them. But then, I have never divided my daffs either.
While my Tommies were flowering, we had some very dull overcast days, but warm days, and the flowers opened wide. I did a post about it at the time as I was thinking that they opened by temperature and not by the sunshine. The bees were flying when we had the warm days and the flowers were open ready for them.
I haven’t seen any bees yet this year. I think temperature plays a role as well as light.
Interesting to learn about the opening and closing of some flowers….. such a complicated process going on beneath these lovely bulbs. I agree about the name, sounds terrible. I love your crocuses by the way, I think I have neglected this bulb along the way…
Never too late to start planting! Aren’t you going into your autumn now?
Yes! This weekend all the bulbs are going in!
Our native bloodroot (Sanguinaria canadensis) closes at night and stays closed on cloudy days to protect its pollen. Ever since I learned this, I’ve paid closer attention to those that open and close and it seems a number of the short-lived, early spring bloomers fall in this group.
Maybe because there is more harsh weather in early spring.
I always thought it was to keep the pollen fresh when there aren’t many pollinators about so they don’t waste it.
That would make sense.
Fascinating. Nyctinasty is vaguely reminiscent of old cigarette butts. Pollenbrella (or pollumbrella) would be much nicer.
I agree with you on both points.
Great post! And I agree with you about the name. Sounds like a personality disorder.
Could be a personality disorder, but pagedogs suggests old cigarette butts, which is also plausible.
Ha, yes, weird name. I’ve observed flowers closing at night and on very dull days and thought it was a pollen preserving mechanism. Plants are amazing. Love your jewel-like Tommies.
Thanks. And of course there are the flowers that open only at night, which is the same phenomenon in reverse.
I think warmth must play a role too though as when I brought some indoors they opened up immediately… I bet there’s a weird name for that phenomenon too!
Now I’ll have to go searching for it.
Your Tommies are wonderful. Would love to have some large clumps like that.
Do crocuses grow well in your area?
Yes, I see them in other gardens. I have only a few but should try to add some this year.
I don’t know, Jason…when they let those marketing folks choose names, they can come up with some pretty dorky doozies. Fun info, and another wonky term that will never come up in polite conversation.
Isn’t it delightful how the sight of something like a crocus can carry us back to childhood?
Who says conversations have to be polite?
I do like all your crocus, especially the yellow ones, it’s just struck me that mine are all white, purple and blue.
How fascinating to learn how flowers actually open and close! I’m with you re the word though…..sounds dodgy! I still love cherry blossom as it reminds me of my childhood.xxx
No cherry tree at our house. Flowers and other things that impressed us as children continue to have special meaning when we become adults, I think.
Your Tommies look great. They make me think I should plant more.
Couldn’t hurt!
Flowers that do this really rely on their pollinators. I bet you have noticed all the bees on them. Honeybees get a jump on the season with them. In fact, I see more honeybees than the early native bees getting nectar and pollen. Did you ever notice pumpkin flowers that close at night? Sometimes a squash bee gets stuck in them overnight and is dead by the next morning since the flower only lasts one day. I have looked for bees in crocus, but never found one from the night before. The honeybees are a lot smarter, plus the flower will open and let them out anyway.
We haven’t seen any bees yet this spring, though in the past we have seen bees on the Crocuses and Snowdrops.
That’s interesting. I’ve never thought to look into it, so I’m glad you did.
Glad to be of service.
I’ve always been fascinated by this activity, but I wasn’t familiar with that term. Thanks for the new information! You have a lovely collection of Crocuses!
Thanks!
you’re spot on about the name-giving talents of botanists. Weeeird…
Maybe they just need to get out more.
Well that explains it. Agreed, funny old word.
And rather awkward.
Regardless of process or science, they are a lovely collection of crocuses (crocii?)
Thank you.
Well thank you yet again for a new word. It’ s a beauty. am going to start to casually drop it into conversation when talking to my gardening friends. I bet it will baffle them.
All the best words do!
Well look at that. I knew so many flowers open wide for the sun but never considered the science behind it. Amazing.
Not sure if I’ll be adding to my vocabulary though, nyctinasty… quite a mouthful.
And not a very pleasant-sounding mouthful, at that.
Nyctinasty sounds like an STD. I love crocus, too, although I have no idea what the names of any of mine are. They’re all just ‘the crocus’ and seem to be fine with their status in the chorus instead of lead singer. Spring without crocus would be horrible.
I only know the C. tommasinianus. The rest are C. vernus, I think.
You had me chuckling at the name Nyctinasty…sounds like a disease. And I love those patches of crocus…mine are small due to voles who love the crocus.
Rabbits and squirrels often bite off the flowers of my Crocus but they’ve been left alone this year.