With less than a week to go, it really feels like time to get back to thinking about the plants we’ll see in India. One thing we’d hoped to do last year, but didn’t really have time for, was to look at how the way in which plants are pollinated varies with factors such as altitude (see A case study in plant evolution).
In ‘Why are flowers pretty’, I explained how plants go about ensuring that they can exchange pollen with other individuals in a variety of ways, using the wind, insects or animals. One iconic plant we will see early on in our trip, in the Mughul gardens of Srinagar, is Magnolia grandiflora.
Though M. grandiflora is a native of the south east USA, introduced to Kashmir, there are two magnolia species native to the Himlayas; M. campbellii and M. globosa
Plants in the magnolia family (Magnoliaceae) were amongst the earliest flowering plants to evolve, some 100 million years ago. They have tepals rather than separate sepals and petals and these, along with the stamens and carpels (male and female parts, respectively) are arranged in a spiral – indicative ‘primative’ features. Magnolias are pollinated largely by beetles, having evolved before the bees, moths and butterflies which pollinate many other flowers.
Whereas flowers and their pollinators have often evolved together to maximise efficient pollen transfer (think bee orchids), both magnolia flowers and beetles lack many of the adaptations which streamline this process.
Bee orchid flower, Ophrys melifera, with pollinia poised for deposition on the back of an unsuspecting bee
Beetles have jaws adapted for munching plant material rather than delicately supping nectar, like a moth or butterfly, so magnolias have thick, waxy petals to avoid the risk of being eaten in the process of being pollinated.
Meadow brown butterfly supping nectar from a rather chewed buttercup
The ovules and developing seeds are well protected within tough carpels, for the same reason.
Beetle pollinating Magnolia. Image: https://theheartthrills.wordpress.com/tag/magnolia-slope/
We did do a little informal spotting of pollinators last year …
Hopefully we will get the chance to take a more systematic look at the issue this time around and see whether we can determine any patterns in pollinator types.