Three Geraniums

Herb Robert, Geranium robertianum, on my street in Hayes, 12 May 2013.

I am taking part in the London Flora Project, which aims to update our knowledge of which plants can be found in the Greater London area.  I have a square kilometer to survey that includes my house and street, and I am finding that it sharpens my perceptions and improves my knowledge of what surrounds me.

Yesterday I found three species of Geranium on my own little street, growing in the verge or in cracks in the paving and asphalt.

So here they are, starting with  a well-known woodland plant, Herb Robert (above).  The leaves are finely divided, and in dry or sunny places are often tinged with red, as here.  It has pretty pink flowers, or sometimes white ones.  (There's a white one in this post: Spring at Keston).

Shining Crane's-bill, Geranium lucidum, on my street in Hayes, 12 May 2013.

This next plant is one of several specimens growing in the cracks.  Look how shiny it is compared to the Herb Robert!  The flowers are quite similar, but the leaves are very different.

I thought of this as a tall woodland plant and I was very surprised to see it here, hugging the ground, but looking around on iSpot I can see several observations in similar places.

Flower of Shining Crane's-bill, Geranium lucidum, on my street in Hayes, 12 May 2013.

The third geranium is a tiny, humble thing that hides in the short grass in a mown verge. The flowers of this one are noticeably different, in that the petals are deeply notched so that one looks like two.  It actually has only five petals, like the others.

Dove's-foot Crane's-bill, Geranium molle, on my street in Hayes, 12 May 2013.

That's true of several Geraniums. There are two possibilities when identifying a plant that looks like this; it could either be Dove's-foot Crane's-bill or Small-flowered Crane's-bill.  You can sort them out by counting the stamens, in theory, but in practice they tend to fall off easily, and if some are missing the count will come out oddly.

Closeup of Dove's-foot Crane's-bill, Geranium molle, on my street in Hayes, 12 May 2013.

So you need to look at the hairs on the flower stem.  If they are all short, it's a Small-flowered.  Here, there are some short and some longer, so it's a Dove's-foot.

So, three wild Geraniums just outside my door!  I am pleased.

Another Insectivorous Plant

Flower of Butterwort, Pinguicula grandiflora, on my balcony in Hayes.  12 May 2013.

I have had no luck with Butterworts in the past.  Twice I have bought one and watched it slowly die.  But nevertheless, I tried again.

In January 2012 I bought a few small hibernacula of Pinguicula grandiflora.  These are the form the plant takes when it hibernates in winter, like little green buds.  It makes a bunch of little offshoots during the year, and these are what I bought, in their winter form.

They grew, and then they disappeared, only halfway through the year.  Well, I had seen some Sundew species do something like that, so I thought they might still be viable.  I put them out on my balcony and kept them wet.  And waited.  Squirrels dug them up, and some of them disappeared completely.  I was not too hopeful, but when I looked under the surface this spring I found lots of little hibernacula.  This time I just left them outside, though I put a few into different pots, some of them indoors.

Butterwort, Pinguicula grandiflora, on my balcony in Hayes.  12 May 2013.

The squirrels dug them up again, and I pushed them under again.

Now they have all come up, and the ones that are outside are all flowering!  So the answer to cultivating these is: leave them outside, keep them wet, keep the squirrels off them, but otherwise ignore them. 

Butterwort, Pinguicula grandiflora, on my balcony in Hayes.  Detail of leaf with trapped insect.  12 May 2013.

This is how they eat insects.  They are not spectacular like Venus Flytraps or Sundews.  At most, the leaf edges can curl up a little.  But a close look  at the leaves shows that they are covered with sticky-tipped hairs, smaller than a Sundew's but the same kind of thing.  When an insect gets stuck, glands in the leaves exude digestive juices, and the result is absorbed into the plant.

Wikipedia says the flower stems are long so that pollinators are kept well away from the leaves and don't get eaten, but I notice that the flower stems of mine are also covered with sticky hairs, so I am not convinced.

Tiny Beauty

Drosera pulchella on my windowsill in Hayes.  7 May 2013.

This exotic bloom is a miniature, only 12 mm across.  It's a Sundew from south-western Australia.  The whole plant that it belongs to is only  2 cm across.  I posted a photo of it here:
Drosera pulchella.

Here's another shot showing the slender flower stalk and the rosettes of the parent plant.  As you can see, it's an insect-eater, though because of its size it can only catch very small insects.  It gets the occasional fruit fly from the kitchen.

Drosera pulchella on my windowsill in Hayes. 7 May 2013.

Heterostyly

Pin-eyed and thrum-eyed primroses on "Primrose Bank" off Cudham Road.   29 March 2011.

A few flowers have a very interesting method of ensuring that they do not pollinate themselves, but are always fertilised by pollen from a different plant.  It is called heterostyly, and works like this.

Some individuals have their anthers at the ends of long filaments, and stigmas on short styles.  Others are the opposite; long styles and short filaments.  The best known examples are primroses, like those shown here.  If you can see the round stigma, the pollen-bearing anthers are down out of sight.  A flower that looks like this is called "pin-eyed."

If, instead, you can see a cluster of anthers covered with pollen, then the stigma is out of sight below.  These flowers are called "thrum-eyed."

So, if an insect goes to collect nectar from the nectaries at the base of the petals, pollen will rub off on it in one of two positions.  This position will match the position of a stigma on a different plant, but not on the same plant, not even another flower of the same plant.

Of course this is not perfect, because pin-eyed pollen could rub off onto a pin-eyed stigma as the insect works its way inwards.  But there is more.

Another common heterostylous plant is Forsythia, the bright-yellow-flowered shrub that's popular in gardens and hedges.  It's in full flower now, but when I looked round, I could only find thrum-eyed examples.

Forsythia x intermedia on Saville Row, Hayes.  Thrum-eyed.

This is a cultivated hybrid, propagated by cuttings, so it is quite possible that there aren't any pin-eyed plants of this variety in this locality.  That would explain why they don't seem to set fruit.  Of course the natural species, which I haven't seen, would have both types. They aren't native to Britain.

As well as the heterostylous positioning of pollen and stigma, these Forsythias have another trick.  Their pollen starts off with a chemical that inhibits germination; and pin-eyed and thrum-eyed plants produce different chemical inhibitors.

The stigma of one type of flower has an enzyme that puts the inhibitor from the other type out of action, and allows the pollen to go ahead and germinate.  So if pin-eyed pollen does get onto a pin-eyed stigma, it stays inhibited, and it just can't germinate.  Only thrum-eyed pollen will find a welcome here.  (I don't know whether primroses do this.)

There are even plants that have three different lengths of filament and style, so that the flowers come in three varieties.  One of these is the Purple Loosestrife. I know a few places where this grows.  It flowers later in the year, and when it does, I will see what I can find!

You might wonder why it is important that plants should not be self-fertilised.  Some plants seem to do very well without needing to be cross-pollinated.  The theory is that for heterostylous plants, the genetic diversity provided by regular cross-pollination gives these plants an evolutionary advantage.

[The information about chemical inhibitors in Forsythias comes from an abstract I found on line: "Zur Physiologic und Biochemie der Selbststerilitat bei Forsythia" by F. Moweus, published in the Biologisches Zenralblatt, 1950, vol. 69, pp. 181-197.]

Bees and Flowers

Marsh Marigold, Caltha palustris, in the pond in Spring Park, 24 April 2013.

I was in Spring Park recently and I was pleased to see a good display of Marsh Marigolds in the pond.  It's an artificial pond, lined with rubberised plastic to retain water, fed by one of the springs from the hillside it sits next to.

You can just about see, if you enlarge the photo, a dot on one of the flowers a little right of centre.

Bee on a Marsh Marigold, Caltha palustris, in the pond in Spring Park, 24 April 2013.

It's a bee.  A solitary bee, not a hive-dwelling honey-bee. 

Yellow-legged Mining Bee, Andrena flavipes, on a Marsh Marigold, Caltha palustris. Spring Park, 24 April 2013.

In fact it's a female mining bee, so-called because they dig holes in tightly packed earth in which to lay their eggs.  I have shown these bees before, here: Andrena flavipes in Jubilee Country Park and here: Andrena flavipes on Keston Common. The second link shows one of the holes.

This one is a female.  There were males around as well:

Yellow-legged Mining Bee, Andrena flavipes, on a Marsh Marigold, Caltha palustris. Spring Park, 24 April 2013.

This one was feeding on a dandelion near the pond.  Their home is a footpath that runs along the base of the wood.  I would have liked to get a photo of one of the bees entering or leaving a hole, but they are extremely wary when they are on the footpath, which is a reasonable response given the number of people and dogs who go along it quite unaware of their presence.  (The people are unaware; I can't vouch for the dogs, but they ignore them.)

Spring flowers and spring insects!  At last.

On The Grassland

Patch primarily of Primrose, Primula vugaris.    Burnt Gorse, High Elms, 20 April 2013.

So, the last two posts were in Cuckoo Wood.  It will be full of bluebells soon.  Meanwhile, though, there are also early flowers on the patches of chalk grassland in the High Elms estate.

Primroses are among the first flowers people expect to see. 

Primrose, Primula vugaris.    Burnt Gorse, High Elms, 20 April 2013.

But if you look at the top photo, you can also see another early flower.  Several types of wild violet come out in Spring.

Hairy violet, Viola hirta.     Burnt Gorse, High Elms, 20 April 2013.

The fragrant Sweet Violet, the Early Dog-violet and the Common Dog-violet can be found in the woods, and this one typically grows on chalk grasslands.  This Hairy Violet and the Dog-violets are very much alike, but the dog-violets have pointier sepals.

Hairy violet, Viola hirta.     Burnt Gorse, High Elms, 20 April 2013.

The area known as Burnt Gorse, from a name on an old tithe-map, is grassland, but once it gets going you will have to look hard to see the grass amongst all the wildflowers.  Even now, about half of what looks like grass in the top photo is actually small sedges.

More Green Flowers

Green Hellebore, Helleborus viridis.  Cuckoo Wood, High Elms, 21 April 2013.

Following my post on the Moschatel the other day, it struck me how much of the woodland floor is covered with green-flowered plants at this time.

The Green Hellebore is a good example.  It's not exactly common, but there is a nice patch of it right next to those Moschatels.  As you can see, it's right next to the road.

Green Hellebore, Helleborus viridis.  Cuckoo Wood, High Elms, 21 April 2013.

 The flowers droop, but if you turn them up, this is what they are like.  The green spreading parts are sepals, not petals.

I posted a related plant recently - a Corsican Hellebore.

Dog's Mercury, Mercurialis perennis.  Cuckoo Wood, High Elms, 21 April 2013.

This one, on the other hand, is really common.  The woods and hedgerows are full of it. 

Dog's Mercury, Mercurialis perennis.  Cuckoo Wood, High Elms, 21 April 2013.

It's related to the Euphorbias you often see as garden plants, which have clusters of yellow-green flowers. 

As a contrast, here's one with no green at all:

Toothwort, Lathraea squamaria.  Cuckoo Wood, High Elms, 21 April 2013.

This plant is a parasite on tree roots, usually Hazel,  and has no chlorophyll of its own. 

Toothwort, Lathraea squamaria.  Cuckoo Wood, High Elms, 21 April 2013.

 You can find this next to paths and roads too. You have to watch out for it.  I missed it at least twice, but once I had my eye in I saw it next to a path I had walked down earlier the same day.  If you know what you're looking for, you have a better chance of seeing it.