Wednesday, 16 October 2013
High up in our Tropical Glasshouse, jellyfish dangle from the stems of a plant named after Napoleon Bonaparte. Well, jellyfish-like flowers, and aren't they just cute!
The genus Napoleonaea was created by the French botanist Palisot de Beuvois in 1804, the same year Napoleon I created himself as Emperor of the French. So an intriguing name for an intriguingly flowered plant.
Napoleonaea is a member of the tropical family Lecythidaceae and includes about eight species, all from Africa. Napoleonaea vogelii is common and widespread species, a small tree (up to 20 metres) found on well drained soils above streams.
The flowers are quite remarkable. One of our IT staff, Joe Ng calls it the jellyfish flower and you can see why. In my two pictures, the outer ring of petals have collapsed leaving two structures formed by sterile male structures (staminodes) - an flared ring of 'spines' and an inner cup. Inside you can see the now widely opened, inner chamber where all the functional reproductive parts of the flower reside.
A paper by Dawn Frame from Montpellier and Sebastien Durou from Toulouse on the biology of this species makes special reference to its insect visitors, including thrips, a small moth, four different kinds of beetle, three kinds of weevil and two kinds of ants. Each of these insects finds a different place to hang out on the flower and the thrips are the ones that seem to do the business - i.e. take pollen from one flower to the next. The rest are freeloaders.
Frame and Durou consider the flowers of Napoleonaea to be 'among the most complex among extant flowering plants'. This complexity, they hypothesise, assists in the passage of insect visitors and whether or not they pollinate the flower. Most insects simply can't reach the functional male bits (the anthers), which are tucked into a protected central chamber until later in the flower's cycle. So the flower segregates rather than excludes insects.
What attracts at least some of these bugs is a chocolaty scent, strongest in the middle of the day. Unfortunately the flowers were up too high for me to savour. In fact Frank Udovicic, Research Manager at the Royal Botanic Gardens, suggested a step ladder might be needed for the height challenged (Frank is very tall, Napoleon of course is caricatured as short) to photograph the flower.
I took mine by holding my phone aloft. I'm not quite sure how Joe Ng, a week earlier, took this but he did manage to capture a flower before the full collapse of the petals.