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Monday, May 31, 2010

Cobaea scandens, Cup-and-Saucer Vine

A packet of seeds is still one of the best bargains around and you can germinate, grow and flower this tropical vine - the cup-and-saucer vine Cobaea scandens - in a single season, although in its native tropical America it grows as a perennial. In the UK you can grow it outside against a sunny wall, but it flowers more reliably in a conservatory, where it will quickly climb to the roof, clinging on with slender tendrils.

It's pollinated by bats and at dusk - at about the time that bats would emerge - the flowers emit a musty scen that attracts them. The bats visit for nectar but as they probe the flower those protruding stamens dust their furry chests with pollen that they transport from plant to plant. Cobaea pollen grains have an extraordinarily beautiful pattern of hexagons and pores on their surface when viewed under the microscope.

Pancrace Bessa, Flore des Jardiniers, 1836

Wednesday, May 26, 2010

Eschscholtzia californica, Californian Poppy

Easier to grow than to spell, Eschscholtzia californica, the state flower of California, is the botanical visual equivalent of a perfect, sunny-side-up egg yolk.... and there is an indirect link between orange flowers like this and egg yolks.

Birds can't make the yellow cartenoid pigment that's a component of petal colour in California poppy and many other yellow-flowered plants, so all the yellow pigment in birds' plumage and egg yolks has to come directly from the plant food that they eat, or indirectly from animals that they eat that have in turn eaten plants with the yellow pigment. For example, blue tits that have eaten caterpillars that have eaten plants deposit the yellow pigment in their breast feathers - so a blue tit that has bright yellow feathers is likely to be a good caterpillar hunter. It has been know for poultry farmers to feed orange marigold petals to hens so that they produce eggs with more intensely yellow yolks.  

Mammals can't make carotenoids either so plant carotenoids are the source of vitamin A which is a vital human visual pigment, which is why carotenoids have been genetically engineered into Golden Rice, to help prevent blindness in communities that have low levels of vitamin A in their diet.

Aside from its glorious golden flower colour, California poppy has very attractive glaucous green, feathery  foliage. I grew it in my garden last year and was delighted to find that it had self-seeded and that they seeds had survived our recent hard winter. Little glaucous green seedlings are coming up all over the garden.

Thursday, May 20, 2010

Dandelion, Taraxacum officinale

Even digital botanic gardens have weeds - in the case of mine, dandelions Taraxacum officinale agg. Dandelions are cosmopolitan weeds and long ago the European species was introduced into the United States, where it has become a major weed. Part of this plant's success can be attributed to its reproductive system, where it sets seed without the need for pollination, and its prolific seed production is coupled to an extremely effective wind-assisted seed dispersal mechanism. Back in 2007 two researchers at Purdue University in Indiana, Tamara McPeek and Xianzhong Wang, were curious to know how this plant might fare in future world where carbon dixide levels were double those of today - which is likely to occur around 2080. For the grandchildren of today's gardeners, their findings make ominous reading. The plants produced 83% more inflorescences and 32% more seeds that were larger, germinated better and established faster. Not only that, but they travelled further because their parachute of hairs (the pappus) was larger and carried the seeds further on the wind. Source: Tamara McPeek and Xianzhong Wang (2007) Reproduction of Dandelion (Taraxacum officinale) in a higher CO2 environment. WEED SCIENCE Volume: 55 Issue: 4 Pages: 334-340

Friday, May 14, 2010

Dicentra spectabilis

Dicentra spectabilis, which comes from Japan, is one of those plants that's perfect for planting in a spot where a shaft of early morning or late evening sunlight can illuminate its arching stems of dangling flowers. This is a plant that has alternative common names ...... so what do you see when you look at an individual flower ....?

.... Dutchman's breeches, as portrayed in this image of well-trousered 17th. century Dutch gentlemen....


... a Bleeding Heart?

Guess it depends on whether you are of a romantic disposition (or a cardiac surgeon) ....

Saturday, May 8, 2010

Scopolia carniolica

This sinister plant, Scopolia carniolica, has been lurking in the undergrowth in my garden for several years, slowly spreading via underground stems. The dried-blood coloured flowers, which look as though their tubular corolla has been snipped neatly across with scissors, are not particular notable but it’s the chemical constituents in the plant that are interesting. Scopolia, like many other members of the potato family, is notorious for possessing a wide range of highly poisonous alkaloids. In terms of toxicity, this plant is almost in the same league as deadly nightshade but one particular alkaloid, scopolamine, has given it notoriety. Used in minute doses this compound has been used to treat travel sickness, usually administered in patches that allow it to be slowly absorbed through the skin. At higher doses it’s lethal, but at some point before that delirium and hallucinations set in. Legend has it that witches made a magical ointment from the plant that produced hallucinations of flying when they smeared it on their skin, presumably just before mounting their broomsticks. More recently scopolamine has been tested as a ‘truth drug’ and has often features in spy thrillers..... you know the scenario.....”Ah, so, Mr. Bond, we meet again ..... and this time there will be no secrets’ll tell us everything.... now, you’ll just feel a small prick.... etc. etc.”

Wednesday, May 5, 2010

Pleone bulbocodioides

The very mention of the word 'orchid' conjures up images of exotic flowers from tropical climates that are expensive and difficult to cultivate - temperamental prima donnas of the plant world. That may be true of some of the epiphytic species but this little Pleione ground orchid from southern China couldn't be easier to grow. Provided it's kept dry in winter it's hardy - mine sat in a frozen greenhouse all winter - and the pseudobulbs steadily multiply, gradually filling a pan with flowers that are produced in May, before the leaves expand.