29/04/2019
Miracles of nature. Here are leaves of Greenhood Orchids breaking the soil surface from underground storage tubers, in April. Ending their ‘go slow’ summer dormancy.
Why just now? There has been no significant rain yet. Is it akin to the spell that overtook 'Sleeping Beauty' and now they are gently waking? Did an ugly prince or sweet little toad kiss them?
Did they get a WhatsApp / Instagram/ email / Facebook post or catch the radio news that daylight saving had finished? That the day lengths are getting shorter?
Plant dormancy is a growth–stress survival trade-off where everything in the plant slows down. During spring orchid tubers accumulate moisture and starch; then remain in suspended animation over summer, very slowly using up these stores.
I am beginning to regret taking on this topic, FYI. When discussing dormancy in summer-dormant bulbs, there are many more unknowns than knowns.
What we do know: seasonal cues of daylength and temperatures are part of turning on and off dormancy. But this is too simple.
What makes an 12/13-year-old human suddenly get long ‘giraffe-legs’. Not just day length and temperature, me thinks. Hormones, baby! Same with plants – yes, plants have hormones.
Plants have at least 9 different types of hormones (phytohormones). They are the Stop, Grow, Warning, Change, and Ripen traffic cops in plants.
Aha …….finally…., I found a reference to Greenhoods - they have a speed-up-making-that-tuber hormone called Jasmonate.
Now I need a lie down and a strong cup of tea.
Use your favourite search engine to check out “How many plant hormones are there?”