You might think, ‘Because it gets warm, idiot’. Shut up.
The actual answer has to do with the cold, rather than the warmth. The process is called “vernalization”. Plants actually begin this process after a month or so of freezing temperatures, which is a good indicator that spring will be a’comin.
One particular specie of plant, arabidopsis or ‘thale cress’, had it’s entire genome sequenced in 2000. Scientists discovered a gene that they, in a fit of creativity, named ‘COLDAIR’, or in Latin frigida (seriously). COLDAIR gets switched on after that long period of freezing temperatures and progressively turns off a gene responsible for inhibiting flowering, over a period of six weeks.
Then bees do it with them. SCIENCE!
Sources :
How Flowers know it's Spring: http://www.calacademy.org/sciencetoday/how-flowers-know-its-spring/
Vernalization : http://en.wikipedia.org/wiki/Vernalization
5 comments
Antanarive says:
Mar 28, 2011
Yes, and the vernalization can be used for space experiments: you bring up “dry” seeds at ambient temperature. You can keep them for a long time like that. When you want to start the experiment, you put them in a fridge for some time; you take them out back to ambient and they will soon germinate…
jarrettgreen says:
Mar 28, 2011
BRILLIANT!
Kait says:
Apr 8, 2011
How did my grandmother’s indoor christmas cactus bloom at the same time every year?
jarrettgreen says:
Apr 8, 2011
My first knee jerk reaction was that an indoor plant would perhaps have a swapped vernalization – I would think that homes would be colder in the summer due to A/C usage, and heater in winter, but….
“Christmas cactus will bloom if given long uninterrupted dark periods, about 12 hours each night. Begin the dark treatments in about mid-October to have plants in full bloom by the holidays. You can place the plants in a dark closet from about 8 P.M. – 8 A.M. each night for 6-8 weeks or until you see buds forming. ”
In other news, this is how pot is grown too I believe, so you should’ve checked you’re grandmother’s closets.
Hermest99 says:
Feb 1, 2012
Well.. it’s actually mostly because they can measure the lenght of day and night, and they know when the nights become shorter.