tisdag 19 januari 2016

Why so early flowering?

I got following question from a reader:

I have a yellow flowered eranthis that always flowers in January in my garden in Scotland. This year they appeared about 1st January when the soil temperature and light levels were minimal. I am curious about the physiology that initiates the process and also the evolutionary factors that caused the plants to chose mid winter to flower. I would appreciate any information.

Best wishes, Tony. 

Continental adaptation and competition
for pollinators are 
key factors for early flowering.

Dear Tony!

I would suggest two reasons for early flowering, both results of evolutionary adaptation. The common winter aconite is a continental floristic element with a typical continental response to seasons. Continental plants start to grow as soon as the first spring heat appears; they respond mainly to temperature and are adapted for clear seasonal changes. When the spring starts in a continental climate setbacks are unlikely so they “know” the spring is for sure. When we move winter aconites from central Europe to maritime Scotland we also move this behavior and they start to grow at the first spring heat there are! Also in southern Sweden there I garden they start to grow in early January since our real winter starts in mid-January and ends in March. Fortunately they are very patient and hardy, so they survive every year and flower in March.

The second answer is, it’s advantageously to flower early because you escape competition of other flowering plants and get all pollinators for yourself! The drawback is if you start to flower too early there are now pollinators awake. The solution of that problem is that many extremely early flowering species have evolved self-pollination or apomixis, so they will set seed without help of pollinators. This is very evident in the two Ranuculaceae genera of Eranthis and Hellebores; you can inbreed both genera and get seedlings in behavior and morphology very close to their parents. All Hellebores breeders today use that phenomenon and most hellebores cultivars you buy are strains and not true clones. Of that reason you also can inbreed cultivars of Eranthis, like double forms, or orange forms.

These two reasons, continental adaptation and competition for pollinators, I would say is the key factors for early flowering in your Scottish garden.

Best wishes

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