Thursday, 28 April 2011

Cooking with Nigella

See what I did there?

This is actually about a spice we don't use much in New Zealand, Nigella sativa, sometimes called black cumin.  I needed some for a Turkish recipe—cornbread with raisins—a few weeks ago, and bought a few seeds on TradeMe.  Later I found the local delicatessen had it in stock.

Nigella damascena (the name means from Damascus) is a cottage garden flower we don't grow often enough.  I know it as "love in a mist".  It's a member of the buttercup family Ranunculaceae, but you wouldn't guess that based on its superficial appearance.  It has pale blue flowers, and clusters of fat seed pods (technically follicles) that open at their tops to release the large black seeds.  It's the seeds of N. sativa that are used in cooking, mostly in middle eastern confectionary and as a garnish on bread (Eastern Mediterranean and on Naan bread).  I've got my seeds now, and will sow them soon, in the dark as recommended.  They have quite a strong smell, a bit unusual and hard to describe, and they're a nice addition to the cornbread.

Nigella seeds on the cornbread

Sunday, 24 April 2011

"The warm wind blows gently and the red poppies dance" (Eric Bogle)

New Zealand servicemen's graves, Karori, Wellington

In New Zealand and Australia, we remember the dead of World Wars 1 & 2 on ANZAC day, 25 April.  Gallipoli was the battle that joined our countries at the hip, and forged a close relationship that today sees us helping each other through devastating earthquakes, floods, and bush fires.

My grandfather, Donald Collins, wasn't an ANZAC (Australia and New Zealand Army Corps) because, like all my ancestors, he lived in Britain.  He served in the British Army, King's Liverpool Regiment 1st/5th Battalion, which fought at Givenchy and the Somme.  He survived the war, but he died of erysipelas in 1921 (probably not war-related), some years before the discovery of antibiotics that would easily have saved his life.

Botanically, World War 1 is symbolised by the Flanders poppy, Papaver rhoeas.  Poppies, with their prodigious seed production and rapid growth, were well suited to colonise the bare ground of the battlefields at the Somme, Ypres, and Paschendaele.  The winter mud, churned up by the tanks, the shell bursts, and the tramp of feet and hooves, fertilised with the blood of men and horses, was ready in the spring for the germination of millions of seeds.
Papaver rhoeas, Sete, France.

So the poppy is a symbol widely used in poetry and songs as the emblem of ANZAC day in Australasia and Remembrance Day (Nov 11) in the UK and other countries.

There's not an equivalent plant for World War 2, but I like the hardy weeds that sprang up on the bomb sites in London.  Even with Christchurch in ruins from the Feb 22 earthquake, and the daily aftershocks, it's hard for New Zealanders to imagine living in London and other European cities as the bombs rained down night after night.  Among these special plants is rosebay willowherb (Epilobium angustifolium), which relishes such disturbed sites and is still widespread on waste land in Europe.

Galinsoga parviflora, Otari, NZ.
But I prefer an unassuming weedy member of the daisy family (Asteraceae) called Galinsoga parviflora.  It's a common weed of disturbed ground in many parts of the world, including here in New Zealand, although it's originally from South America.  One funny thing about it, with a wartime link, is its common name: gallant soldier.  It's easy to imagine this name is derived from a mis-hearing of its scientific name:

"'Ere Flo,  wossname of this weed then?"

"Well, I heard some gent called it somefink like gallant soldier!"

However, I'd be interested to know if this name was in use before the war, because that's its common name in the US as well as in Britain.

Weeds are supreme opportunists.  By producing seeds in huge numbers, they're well suited to colonise disturbed ground.  Poppies, willowherbs, and Galinsoga had all the right attributes to make the most of the battlefields, and in doing so they brought a little beauty and new life to the devastated waste lands of human folly, bigotry, intolerance, and greed.

Thursday, 21 April 2011


Cygnet’s my sailing dinghy.
She’s a John Welsford designed “Daniel’s Boat”, made by Peter Murton.  Just a shade over 3m long, with mainsail and no jib.
Very easy to manage, and beautiful to look at.
Why Cygnet?  Well, my family’s business, Garnock, Bibby & Co., was a rope factory and ship’s chandlery in Liverpool, called the “Old Swan Ropeworks”, Old Swan being the suburb where the factory was.  It was formed in 1838 and sold off in the 1960s.
My ancestors were sailors, but I’m only just learning to sail.  So the Old Swan becomes the Cygnet in my generation.

Monday, 18 April 2011

Easter: bring on the marshmallow and chocolate.

Two plants that feature in any secular celebration of Easter are Althea officinalis (marsh mallow) and Theobroma cacao (cocoa).  Before Christianity commandeered it, Easter was a celebration of the (northern) spring, renewal of growth and new birth in the plant and animal worlds.  For a more biblical account of Easter plants, I recommend Hepper's Planting a bible garden (reference below).
A weedy wild mallow (Malva sp.)
photographed in Italy
Mallows are often weedy plants, mostly in the genus Malva (pictured), which gives its name to the family Malvaceae (native members are lacebark, Hoheria, and ribbonwood, Plagianthus).  Hollyhocks and Lavatera are ornamentals in the same family.  The original marsh mallow, Althea officinalis, is called that because it grows in swampy sites in Europe.  Its roots produce a sticky juice that can be used to bind a beaten egg and sugar mix.  Modern marshmallows are made with gelatin in place of marsh mallow root.  The protein in the gelatin holds the whipped bubbles together, producing the sweet fluff that fills an Easter egg.
Theobroma cacao (the genus name means food of the gods) is a tropical tree.  McGee (reference below) has 18 pages on chocolate.  Theobroma fruits are ovoid pods that contain large seeds, the cocoa beans.  These beans must first be fermented carefully in the sugar-rich pulp that surrounds them in the pod.  A series of physical and chemical changes during fermentation reduces the bitterness of the beans and breaks down complex chemicals into simple sugars and a rich array of flavours.  The beans are then dried and roasted.  After roasting, flavours are adjusted by the addition of sugar, vanilla, milk solids, and cocoa butter.  Chocolate should melt evenly into a creamy texture that can solidify again on the outside of an Easter egg. 
Hepper, F.N. 1997.  Planting a bible garden.  Revell.
McGee, H. 2004.  On food and cooking. Scribner.

Orchids: what are they good for?

The word orchid is derived from the Greek word for testicle.  If you've had an orchiectomy, you’ve had a ball (or two) surgically removed.  Most terrestrial orchids grow from a seasonal bulb, so there’s this year’s one that flowers now, and next year’s one that will flower then.  Dig up an orchid and there are two small ovoid bulbs, like a pair of, well, you get the picture.
If you subscribe to the medieval Doctrine of Signatures (and surprisingly many people still do), you’d think orchids should cure all manner of sexual ills, like sterility and erectile dysfunction.  If you subscribe to the homeopathic doctrine of like-cures-like, maybe they’d even be considered useful contraceptives.
So what orchid products are available?  Surprisingly few as it turns out, considering the Orchidaceae is one of the largest families of flowering plants.
I can think of only two commercial products from orchids.
Vanilla is made from the seed pods of the vanilla orchid, mostly Vanilla planifolia, although a couple of other species are grown too.  You can buy cheap synthetic vanilla too, which is a wood by-product.  Vanilla’s an important crop in Tahiti and the Cook Islands, though Vanilla is native to Mexico.
The other orchid crop is less known in most parts of the world.  Salep is an orchid product that’s popular in Turkey and places where Turkish people have moved to, like Germany.  It’s made as a sweet milky drink from ground up orchid bulbs.  But the CITES (Convention on International Trade in Endangered Species) regulations prohibit international trade in orchids, so salep can’t be exported from Turkey to expatriate Turks in Germany and other countries.  As a result, a starch-based substitute has been developed, but it’s not the real thing according to aficionados.  This account of salep preparation is from an excellent Turkish food blog that I follow. 
Given that some of our native New Zealand terrestrial orchids grow like weeds (I’m thinking particularly of Microtis, seeds pictured), wouldn’t it be fun to see if their bulbs can be used to make salep?  (Note added 19 April 2011: Never harvest orchids or other native plants from the wild; the populations aren't likely to be sustainable, and in many areas such collecting is illegal.  But onion orchids (Microtis) pop up often enough in gardens and can be harvested there.)
All orchids have masses of tiny seeds like this.  The seeds don't have an endosperm when they're mature, and they're dispersed on the wind like dust.

Saturday, 16 April 2011

Monocots, eudicots, and basal Angiosperms.

When I was a student, and for several decades after, a remarkable group of very knowledgeable botanists progressively put forward their ideas about how the 250,000 flowering plant species were related to each other.  Foremost in this group were Armen Takhtajan (USSR), Arthur Cronquist & Ledyard Stebbins (USA), and Rolf Dahlgren (Denmark).  Bill Philipson (University of Canterbury) was New Zealand’s main contributor of ideas to this ongoing programme, and Bruce Sampson (Victoria University of Wellington) contributed critical information on flower anatomy and pollen grain structure.  In spite of their considerable combined intellect and knowledge, they never agreed on an overall scheme that was stable.
Two things changed all that in the 1980s and 90s.  First, biologists realised that the centuries-long search for a natural classification meant seeking to discover and name only those groups that had evolved from a single common ancestor.  That significant insight came from East German entomologist Willi Hennig in the 1950s, and it took a while to be applied to plants.  Secondly, cheap and rapid DNA sequencing techniques gave us the abundant and reliable data we needed to begin this search.  One advantage of this explicit, rather than intuitive, approach was that different ideas could be evaluated and compared objectively.
In 1993, a remarkable coalition of 52 botanists led by Mark Chase (now at Kew) published a ground-breaking paper, based on the variation of a gene called rbcL.  This gene, found in chloroplasts, is the DNA code for the structure of the large subunit of a protein called rubisco, which is essential to photosynthesis and very abundant in plants.  Their huge (for its time) data set took over a month to analyse on a Sun workstation.  Later, similar collaborations used other genes, in particular atpB and ribosomal genes, and found very similar patterns. 
In the 18 years since Chase et al. (1993), the family level classification of the flowering plants has been pretty well established and formalised as the Angiosperm Phylogeny Group (APG) system, but a few important problems remained.  In part, these problems could be caused by evolutionary events that followed each other so rapidly that evidence of their history wasn’t left in the DNA of any living species, or they could arise because more recent changes to the DNA have overwritten and hidden that signal. 
One solution was to sequence more genes, widely sampling across the three plant genomes (in the cell nucleus, chloroplast, and mitochondrion).  This month, yet another such grand coalition (just 28 scientists this time) led by Doug & Pam Soltis at the University of Florida, Gainesville, has assembled a remarkable data set of 17 genes for 640 species to address the remaining problems.  Their findings are broadly in agreement with the APG system, but they clarify some important issues.
Since the early 1990s it’s been clear the traditional classification of flowering plants into two large groups must be abandoned.  Most of us learned at school that the flowering plants divide neatly into monocotyledons (with 1 seed leaf) and dicotyledons (with 2).  Modern classifications still recognise the monocotyledons (monocots), including grasses, sedges, orchids, palms, and lilies, which have a single seed leaf, parallel leaf veins, and lack true wood, leaf stalks and taproots.  The problem is that using the opposites of these characteristics to define a second group, the dicotyledons, simply won’t work.  Plants that have 2 cotyledons, wood, taproots, leaf stalks, and net-like leaf veins include not just the remaining flowering plants, but many cone-bearing plants as well.  To find natural groups, we must look for species  that share uniquely evolved features.  In this way, our ideas about classification are based on evolutionarily meaningful evidence, rather than conjecture.  If we look for natural groups, the closest we can get to the traditional dicots is a group that’s defined by the unique feature of having three, rather than one, pore or groove in their pollen grains, a group that’s now called the eudicots or the tricolpates.  Together the monocots and eudicots make up most of the flowering plants. 
But about 3% of the flowering plants are neither monocots nor eudicots.  These fall into a number of small groups and collectively they’re called basal angiosperms.  Although they have two cotyledons, they're no closer related to eudicots than they are to monocots.  One major classification problem has been the order in which the ancestors of the basal angiosperms diverged.
Most of the papers, including this new one, say the first evolutionary split of the ancestors of living flowering plants was between the ancestors of a single living species, Amborella trichopoda, and all the other flowering plants.  Thus, if you wanted to divide flowering plants into two groups, one group would have to be Amborella and the other group would include everything else.  Although many studies find this result, there are some that dispute it.  
Amborella trichopoda grows as an understorey plant in montane forests in New Caledonia (left), and it’s become a bit of a celebrity there.  Why would evolution produce two sister groups with such different evolutionary potentials?  Maybe Amborella is the only surviving remnant of a group that was once much larger, but has mostly become extinct.  Alternatively, there might be something about Amborella that makes it an unlikely group to radiate into lots of different habitats; perhaps it’s always been a very small lineage.
The second major split is also very uneven.  On one side we have just the water-lilies and their close relatives, including a small aquatic plant called Hydatella that until very recently was thought to be a monocot; on the other side, all the remaining flowering plants. 
After that split, a small group of three families, including star anise and its relatives, diverged from the ancestor of all the other flowering plants.  
And then next comes a rather larger group, including among it  a few familiar New Zealand plants like hutu (Ascarina lucida), horopito (Pseudowintera colorata, pictured at right), tawa (Beilschmiedia tawa) and pukatea (Laurelia novae-zelandiae); magnolias and a lot of tropical spices like nutmeg, cinnamon, and camphor belong in this group too.
Those families, from Amborella to Magnolia, are the basal angiosperms, a remarkable and divergent set of plants that have all kinds of interesting and useful features.  But all they have in common is that they’re not monocots (they have 2 cotyledons, leaf stalks, taproots, and net-veined leaves), nor are they eudicots (they have single pores or grooves in their pollen).  They’re not considered a natural group.
In the 17th and 18th centuries, the spices provided by these plants, particularly pepper, nutmeg and cinnamon, drove European exploration and conquest of tropical Asia.  It was said that if a British ship could get to SE Asia and bring back a load of spices without being captured by the Dutch who controlled much of the trade, every member of the crew, from the captain down to the lowliest cabin boy, would be rich beyond the dreams of Croesus.  Even today, spices are high value products, in terms of monetary value in proportion to weight.
Why does any of this matter?  Well, if we can classify related species together in groups, we can make predictions based on those classifications.  This helps in all sorts of economic botany questions, like drug discovery.  It’s also useful to ecologists and evolutionary biologists; if we can classify plants according to their relationship history, we can understand how they evolved and how they have adapted to different environments.  This is a continuation and an application of the questions posed by Charles Darwin: “… from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”
Soltis, D. E. & 27 other authors (2011). Angiosperm phylogeny: 17 genes, 640 taxa.  American Journal of Botany 98: 704—730.

Thursday, 14 April 2011

Plant movements

Plants are stuck in one spot, rooted to the ground, and they don't usually move their parts around much either.  But there are a surprising number of plants that move a bit, although it's often rather slow.  Charles Darwin wrote a book about them.  Many flowers and some leaves fold up at night, for example, and there are seed pods that open quite quickly when a shower of rain comes along to splash the seeds out (especially in the ice-plant family Aizoaceae).  Plants don't have nerves to transmit impulses, nor do they have muscles.  Much of their movement is achieved by changes in turgor pressure, which is the pressure of sap inside the cells.  If cells suddenly swell, or collapse, they can force a leaf or pod to open or close.  Sometimes this works even if the cells are dead, as in some old seed pods.
Perhaps the most spectacular are the traps of the Venus fly trap, Dionaea muscipula, which catch and digest insects in their nitrogen-poor environments.  The traps are specialised leaf tips, and they look for all the world like the gin traps we used to use to catch possums when I was a boy (now illegal, because they're cruel).  They snap shut quickly enough to catch flies and other small insects, which they they digest for their nitrogen.
Our Venus fly trap made a double trap this week. Normally there's just one trap at the end of a leaf, but this leaf has two. I guess something went wrong with the developmental controls, or the patch of cells destined to become the trap got split in two.
Anyway, it seemed a good opportunity to test the signal that shuts the trap. The traps are triggered by a few small hairs on their surfaces. Do the triggers act directly (like a gin trap), or is there a signal sent from the hairs to the closing mechanism? If the latter, then maybe triggering one trap would close them both...