Monday, June 18, 2007

Heartsease pansy Viola tricolor

I am an amateur naturalist attempting to find out something about everything in my garden.

Spreading their way along the front flower-border of my garden are numerous little Heartsease pansies (Viola tricolor). Photo 1 (click to enlarge) shows a solitary plant flowering in early April and photo 2, taken more recently, a patch of its joyously sprawling compatriots enjoying Oxfordshire's recent combination of warm, wet weather. As was the case for the California poppies I wrote about recently, I am in no doubt about the identify of these plants since it was me that grew the first of them from a packet of seed some few years ago.

A tough little creeping perennial, Heartsease is the wild ancestor of the myriad cultivated pansies you can find in your local garden centre. As I learnt from reading the site of the American violet society, amongst the first persons to take a horticultural interest in Heartsease was the British Admiral Lord Gambier (1756-1833) who, when he wasn't battling the Napoleonic fleet, was busy with his gardener William Thompson, breeding the first hybrid pansies. I have to say that I prefer the original, but each to their own!

From my copy of The Englishman's Flora (Geoffrey Grigson, publ. Paladin) I learn that there are dozens of alternative names for my pansy, including the poetic Love-In-Idleness the name used by Oberon in Shakespeare's A Midsummer Night's Dream (Act II, scene 1) when he describes the power the flower has as a love potion:

And maidens call it love-in-idleness
Fetch me that flower; the herb I shew'd thee once;
The juice of it on sleeping eyelids laid
Will make or man or woman madly dote
Upon the next live creature that it sees.

Can anyone out there tell me if this works?!

A name that doesn't get a mention in the book above is 'Johnny Jump Up', the name used in the U.S. I understand.

V. Tricolor is a member of the (approximately four-hundred strong) Viola genus of flowers. The rather asymmetrical (the technical term being zygomorphic) arrangement of the five petals is believed to make it an example of a highly evolved flower. The streaks on the lower petals are supposedly there to act as nectar guides for pollinating insects, these being (in the Netherlands at least, according to a scientific paper I came across by Veerman and Zon, 1964) mainly bumblebees and the Silver 'Y' Moth (Plusia gamma).

There are some excellent sites (this one for example) on the internet describing the botanical details of flower structure. The name and purpose of one structure has eluded my (decidedly non-expert) attempts to identify it however, namely the two white 'lips' that can be seen in the centre of the flower in photo 1 (click to enlarge). Under magnification (photo 3, 40x) these remind me of white-tentacled sea-anemones. No doubt an embarrassing display of botanical ignorance, but can anyone tell the name and purpose of these curious structures?

7 comments:

R2K said...

I love this work so much. I must admit some envy at the quality of your micro-images. My SEM images are a source of great pride to me, but obviously the Proscope images while cool and fun, are not nearly as good as a real quality 'scope. If only my compound or stereo (dissecting) microscopes had a tri head or some camera attached, I could try to get shots like these. With your permission, since I have now hit the end of my latest image set (And need a bit of time off.), I would like to make a post about your page. If you agree, it would be great if I could show one set of images from you (perhaps the most recent). Really top notch work here.

Henry Walloon said...

Many thanks for your too-kind comments. Your own blog makes great reading also.

No problem at all - I'd be pleased and flattered for you to do as you suggest (I ask only that people don't sell my humble snaps themselves for profit and quote their source).

If I may be so presumptious, amongst my own personal faves are the May12th pollen image and the Jan27th moss-leaf cells...but take your pick. As mentioned in the text however, sadly beautiful May19th mite SEM isn't one of mine.

R2K said...

Can you share with me what type of microscope - camera you use? (And sorry if you explain this in the blog and I simply missed the post).

Your images, if posted, will fall under my image policy that states, among other things: "Anyone found using these images in any way without credit and permission, or selling them with or without credit, will be subject to aggressive action on my behalf including litigation."

Henry Walloon said...

Thanks for the comment r2k: my microscope is a Westbury SP30 and my camera is an Olympus 'mu' [the Greek letter] 300 3.2Mpix digital.

Heidicrafts said...

I request permission to use your first pansy image for an Artist Trading Card that I am composing. You can see examples of my ATCs at my blog, listed in my profile.

I will credit you and your blog on the card. These art cards, the size of football cards, are not for sale, only for trading with others. I'm working with a theme of Midsummer Night's Dream, showing your flower and Shakespeare's text.

I can send you a link when I'm done, if permission is granted.

Henry Walloon said...

Heidi

It's a beautiful flower isn't it, and I'm flattered you liked my photo.

I've left a message on your blog to say please go ahead and use it.

Mike Hardman said...

Hi Henry,

Some nice piccies and interesting blog; thanks.

You ask about the beards in the throat of the heartsease flowers...

They are called trichomes.

They help disloge pollen from visiting insects' heads and probosces, whence it falls and collects (somewhat precariously) in the narrowest part of the throat. That is just below the opening on the stigma, which is where the pollen has to get to to enable germination. The pollen may get into that opening directly from the visiting insect (eg. various species of bee), but the trichomes help. There is scope, however, for variations and alternatives to that idea.

The insects have to collect pollen to take to the next flower as well, of course. So things can get a little confused. But generally, in order to reach the reward (the nectar at the end of the spur), the insect has to push against the head of the stigma. And it is that push that causes the stigma to kink and break the box formed by the stamens surrounding it. If the time is right, the stamens will have already shed their pollen, so that box will be filled and ready to dump the pollen onto the insect's proboscis on its way out. There is often a narrow groove in the base of the throat to help concentrate the pollen where the proboscis is most likely to have entered.

But sometimes, the insects cheat! Bumble bees can nip a hole in the spur and sup the nectar directly, thereby not participting in the pollination process. Which might be cunning. ...Because it might induce the flower to keep producing nectar for longer!

Not all species of Viola have the trichomes, but they seem to do OK!

Cheers,
Mike Hardman,
Referee for Viola for the Botanical Society of the British Isles, author of the Viola section of the RHS Encylopedia of Perennials (2006), and Viola articles in The Garden and The Plantsman.