Tuesday, 10 April 2012

Fritillaria, obese genes with a chequered natural history


The Snake's Head Fritillary, Fritilleria meleagris, is the latest bulb to show it's floral head this spring. The large purple bells with a chequerboard pattern are hard to miss, even interspersed with the white form of the same species.

The Kew website lists a few other common names that play on the distinctive flower pattern - Chequer Lily, Checkered (Chequered) Daffodil and Chess Flower - but also a few that don't - Guinea-hen Flower, Leper lily and Lazarus Bells. No time to work out what the hell those last three mean.

The scientific name of the genus comes from fritillus, a dice box, which I gather used be chequered, and meleagris means like a spotted guinea fowl. Ah-ha, one of those common names now makes a strange kind of sense.


Fritilleria meleagris was never a wild species at Kew Gardens but did, according to Tom Cope's The Wild Flora of Kew Gardens, grow naturally* nearby at Mortlake. The blooms pictured in this post are the result of a 30,000 bulbs planted a few years back. My pictures are from Princess Walk but it also grows beside Riverside Walk (next to rather large blue flowering bulb that I'll feature in a few weeks...). There are a thousand or two in the Bog Garden at Wakehurst Place too.

In the wild, Snake's Head Fritillary has spread beyond its natural* range of southern England into the rest of the British Isles. It's also a wild plant in much of Europe but often endangered in its native habitat (e.g. it's extinct in Czech Republic and protected in Poland).

In fact nearly half of the 100 species of Fritilleria are Red Listed - i.e. of conservation concern. All of them grow wild in the Northern Hemisphere but some clearly don't grow as much as they should.


My *s above is because it's not certain that the Snake's Head Fritillary was ever native to England. The earliest report of it growing wild was in 1736, while it has been cultivated in gardens since Tudor times (back to at least 1578).

Now it's only as I come to blog about this species, reading up on it from various sources including our very informative Kew Gardens webpage, that I find that there are two subspecies. Only one grows in the UK, subspecies meleagris. It's also the one found throughout most of mainland Europe, except in alpine areas of France and Italy which are home to subspecies burnatii.

What else should you know about this species? Well from work in the Jodrell Laboratory at Kew and elsewhere we know that a species of Fritillaria (Fritillaria shikokiana) has 30 times more DNA than humans have in each cell, making it the largest (diploid) genome reported for a plant. It more than qualifies as one of the so-called obese genomes.

Kew has a wonderfully named research grant running at the moment called 'Evolutionary dynamics of genome obesity'. Fritillaria is the subject of choice to find out why some plants have lots of repeated DNA sequences.

Even our home grown species, Fritillaira meleagris, has a big genome (i.e. lots of DNA). It's a mighty 15 times bigger than our human one. Our website says that if you unravelled its chromosomes it would stretch over 30 metres (compared to our measly 2 metre long thread).

But please don't do this. The Snake's Head Fritillary is a rare and pretty plant, and it needs its DNA.


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