Tuesday, 10 May 2011

Lammas flowering

One of the many delightful things about J.R.R. Tolkein's Lord of the Rings is the way he brings in words from other languages or archaic English.  I've never bothered to look many of these up, but I always enjoyed the mystical sounds of them.  One of these words is lammas; the fellowship were given lammas bread by the elves to take with them on their journey.  I never expected to meet this word in my capacity as a botanist.

Lammas is a harvest festival, celebrated in England on August 1st, early autumn there.  It's associated with the bringing in of fruit and grains for the winter.

Yesterday I received an email from my colleague, entomologist George Gibbs, who had observed autumnal flowering in hard beech (Nothofagus truncata) along the Butterfly Creek track, eastern Wellington.  Neither of us had seen this before, although occasional autumn flowers can be seen in quite a few spring-flowering trees and shrubs; I'd especially seen it in Rhododendron in mild autumns.  George followed it up in the literature and reported back to me that Dr Lindsay Poole mentions it in his book Southern Beeches (1987), under the term lammas flowering: "buds can burst at the end of summer in a year in which there is going to be a mast flowering in the following spring.  They ‘are unable to contain themselves …’!    Evidently also occurs in European beeches."
Nothofagus truncata forest, Remutaka Range.
Masting is a phenomenon where some plants flower less frequently than every year.  Usually they flower every three years or some other prime number.  One explanation is that it's a way of avoiding predators by making it hard for them to bulk their numbers up in anticipation of good fruiting years.

Schauber et al. (2002) gathered a lot of information about mast flowering New Zealand trees and came to the conclusion that masting is a phenomenon of plants that lay down their flower buds the season before; if that's a warm summer, the plants will flower spectacularly the following year.  Lammas flowering in Nothofagus supports this idea, as the comment 'unable to contain themselves' implies.  Some of the buds laid down in the warm 2011 summer are tricked into opening early in the mild 2011 autumn.  It shows that next year's flower buds are already present, and we can expect a bumper flowering next spring.

Since I received George's comment, I've noticed lammas flowering in Veronica parviflora on the Victoria University of Wellington campus.  Normally this tree hebe flowers in January/February, but it's flowering right now near VUW Press at the Rawhiti Road entrance to the campus.  I don't think it's a masting species though; it's just that the flower buds are probably laid down the preceding summer.
Veronica parviflora, Johnson's Hill, Wellington
Added 14 May: Wineberry (Aristotelia serrata) is sporadically flowering right now too.


Schauber EM, Kelly D, Turchin P, Simon C, Lee WG, Allen RB, Payton IA, Wilson PR, Cowan PE, & Brockie RE 2002. Masting by eighteen New Zealand plant species: the role of temperature as a synchronizing cue.  Ecology 83:1214–1225.

1 comment:

  1. This year all of our four plum tree varieties had a autumn flowering. Two of theme were nude and scheduled for prunning, i wasn't sure what to make of it and after a casual search we didn't find many horticultural references to the phenomenon, no reference to it in plums. These (all?) plums all have an early spring bloom so i presume they too were laying down next buds for the coming spring and couldn't contain themselves?