Saturday, March 29, 2008

White tipped bristle moss Orthotrichum diaphanum

I am an amateur naturalist trying to learn something about everything living in my garden.

Photo 1 shows another of my garden-wall-top's community of mosses. For this photo I was fortunate to be able to borrow a fancy digital camera. I'm most impressed with the close-up ability, as compared with the results from my own humble little 'point and click' camera, normally responsible for the snaps on this site. The Walloon bank balance may need to take a hit at some point!

Photo 2 (click to enlarge) shows a 40x magnified view of a single leaf. Distinguishing features are the circular leaf cells, the central vein that fades out just before the end of the leaf and the 'recurving' (folding over) of the leaf edge. Another obvious feature is the long, white 'hyaline' (=clear) hair at the end of the leaf. Quite a number of mosses sport such hairs (see my previous postings on S.intermedia, G.pulvinata and T.muralis for example). A pure guess on my part is that these hairs act as condensation sites for droplets of dew, thereby helping the moss to collect water. I've no evidence for this however. Can anyone comment? Anyway, regardless of their purpose, these features taken all together identify my moss as Orthotrichum diaphanum in my trusty copy of British Mosses and Liverworts (Watson, Cambridge).

For those of you unfamiliar with the art of moss identification (which included me when I began this blog a year ago ) clicking on 'moss' under the 'labels' menu on the left this screen and scrolling down, you'll easily be able to compare the leaf shapes of the different species I've blogged so far. You'll see that far from being all the same, different species of moss really do have their own individual and characteristic leaf features (some short and fat; others long and thin; some with hairs; some without etc.) - a strong aid to their identification.

O. diaphanum is a fairly common moss. According to my copy of The Moss Flora of Britain and Ireland (Smith, Cambridge) "[it] has been found on such unlikely materials as old linoleum, corrugated iron and tarmac". It is most common on trees and wooden fences.

Another feature obvious in photo 1 are my moss's brown setea (fruit stalks and capsules). The site of the Bryophytes and Buildings project - cataloging mosses in Edinburgh, Scotland - has some superb closeup photo's of the capsules and the 'peristome teeth' that are revealed when a capsule loses its lid. Experts use the shape and number of peristome teeth as another aid to species identification. I've read (though I can't remember where) that a moss's peristome teeth act as little mechanical devices, bending and flexing in response to passing air currents and changes in humidity and actually 'reaching inside' the capsule, 'scooping up' the spores therein, and flicking them out, away from the moss. Another of nature's tiny miracles!

Sunday, March 23, 2008

Myrobalan Plum, Prunus cerassifera nigra

I am an amateur naturalist trying to learn something about everything living in my garden.

In my previous posting I talked about the appearance of daffodils here in Oxford heralding the arrival of Spring (though I might add that when I wrote the posting, the weather was warm and sunny, whilst today we're experiencing strong Arctic winds and snow - there is nothing so changeable as the British weather!).

Another pretty indication of Spring's arrival is the masses of blossom breaking out on the trees and hedgerows. One common example, found everywhere in parks and gardens here in the UK, is the blossoming of ornamental 'Myrobalan' Cherry-plum trees. I have one in my garden (at (0,1.1) - see here) - photo 1 (click on photo's to enlarge)

The botanical name for my tree is Prunus cerasifera, and on the basis that the blossom is pink (photo 2) and the leaves purple-red (see photo 3 taken late last summer), it is an example of the subspecies P. cerasifera nigra. (Were the blossom to be white, it would more likely be an example of the second common cultivar: P. cerasifera Pissardii).

Together with showing the toothed leaf margin (another feature aiding identification) photo 4 shows a closeup of one of my tree's 'fruits' (or, to give them their correct botanical name, drupes - see my previous explanation here). I've no idea what, if any, culinary use it's possible to make of these. Can anyone comment?

Though I intend to make an effort to observe more carefully this year, I also don't know what animals, if any, like to eat the drupes. I guess blackbirds, squirrels and pigeons, at least, might give them a try.

For completeness, photo to 5 shows a closeup my tree's bark, and photo 6 a view of the buds in late January, a few weeks before they blossomed.
And that would appear to be that! Those who follow my postings will know that I normally make some effort to link to websites providing interesting snippets of information on the 'lifeform' under discussion. When it comes to Myrobalan cherry-plums however I've drawn something of a blank! There is a fair amount of scientific literature out there devoted to trying to sort out the genetic relationships between all the various plums, cherries, peaches, apricots and almonds that constitute the Prunus genus. Specifically on the Myrobalan's however, I've found next to nothing of say which the amateur naturalist like myself might find interesting (any suggestions anyone?)

I'll therefore end with my own observation: returning to the closeup of the blossom in photo 2 it's apparent the flowers have 5 petals (5 fold symmetry). Recently I watched a streaming lecture on the physics of crystals on the superb M.I.T., open course-ware, website (as you do!). The lecturer, one Prof. Wuensch, explained that star-fish have evolved five legs since objects with a 5-fold symmetry lack an 'easy' or 'weak' direction along which to tear or rip them (if startfish had, say, 4 legs they'd present a weak axis along which a fish could easily tear them into two, symmetric, 2 legged sections). I will end my posting therefore with The Walloon Myrobalan Blossom Conjecture:

Fruit-tree blossom commonly has 5-petals to make it more difficult for birds (such as Bullfinches) to dismember it.


Friday, March 21, 2008

daffodil narcissus

I am an amateur naturalist trying to learn something about everything living in my garden.
Spring has sprung here in Oxford in the U.K. One of the cheeriest signs of its arrival is surely the great profusion (I'll spare you references to "hosts of golden-" etc.!) daffodils that pop up in our gardens, woodlands and on roadside verges. Photo 1 shows some of those appearing anually in my garden.

In fact, a number of different types of daffodil appear at this time of year in my garden. That I should find more than one is perhaps no surprise since, as I learn from the Warwick Daffodil Genetic Resource webpage, breeders have developed a staggering 25,000 daffodil cultivars! The Royal Horticultural Society site hosts a searchable database. The same site also gives details of the horticultural code system used by daffodil aficionados (narcissists?!) to label varieties. In brief, it works like this:

Firstly, decide which of the 13 divisions of daffodil yours belongs to. In the case of the daff in photo 2, though not obvious from the photo, I measured the central 'trumpet' (corona') as longer than the outer petals ('perianth segments'). This puts it in Divison 1. By contrast, the corona of the daffodil in photo 3 is more than 1/3, but less than the full length of the petals, putting it in Divison 2.

Next, write down a letter for the colour - White, Green, Yellow, Pink, Red or Orange - of the perianth segments. So, photo 2 becomes 1Y, and photo 3 2W. (There are rules on the RHS page above for what to do if your daffodils petals are multicoloured)

Finally, repeat for the corona (adding a hyphen '-'). So finally photo 2 = 1Y-Y and photo 3=2W-Y.

Simple! (Or at least that's my understanding - as always, my amateur identifications come with a health warning - I'm always happy to be corrected. )

Of course it's also possible to be more 'botanical' about things - working through phrases like 'dentate coronal rim'. The ultimate goal must surely be to pin down one's daff's to one of the >25000 listed varities. Breeders have come up with some great names - "Her Majesty Queen Alexandera"; "This Little Piggy" and "Singing Pub" being three that caught my eye. I'd be delighted if any expert out there can tell me the name of the daffodil's in Photos 2 and 3 .

For those interested in doing more than simply naming their daff., the definitive textbook would appear to be "Narcissus and Daffodil, The Genus Narcissus" (Edited by Gordon R. Hanks, publ. CRC Press). I don't own a copy, but rather helpfully, the publishers have put a substantial chunk of the book online. From this I learn that there are about 80 species (as opposed to sub-species cultivars) of Narcissus, forming part of the Amarillidacyeae family of plants that also includes the snowdrops and lillies. Something I'd not really considered was how bulbs grow and expand. The book gives a rather detailed account of this and explains that each year new flesh appears in the centre of the bulb, with progressively older flesh being found further out from the centre. The very oldest flesh ends up as the papery, thin skin one often finds on the outer surface of bulbs. Finally, it seems that daffodil bulbs contain some rather nasty, toxic, alkaloid compounds. This no doubt explains why, although bulbs in my garden commonly get dug up and eaten (by, I assume, squirrels or badgers), this never seems to happen to my daffodils. Britain's wild daffodil is Narcissus pseudonarcissus.

The 1st March is St. David's Day - the patron saint of Wales - and it's common for people to wear a daffodil buttonhole.

I'll leave two last words to William Shakespeare:

When daffodils begin to peer,
with heigh' the doxy, over the dale,
why, then comes in the sweet o' the year.
The Winter's Tale (Act 4, Scene 3)

and from the same play

That come before the swallow dares,
and take The winds of March with beauty
The Winter's Tale (Act 4, Scene 4)