Category Archives: Orobanche

Something’s Got a Hold of my Root: Broomrape (Orobanche)

This is a sort of opener for a series on telling similar plants apart, but I also wanted to say something about these remarkable flowers.

Orobanche gracilis - slender broomrape. Its host,the legume Dorycnium, is in the background

Orobanche gracilis – slender broomrape. Its host,the legume Dorycnium, is in the background

This was the first of these striking inflorescences I saw – pointed out to me by CL, who must be developing a botanist’s eye in order to be able to live with me. It’s Orobanche gracilis, slender broomrape, and like all plants in this genus it’s a parasite, living entirely on the water and nutrients of its host plant , which for this species can be any legume (Fabaceae family – anything resembling peas and beans).  The plants are distant relatives of snapdragons and toadflaxes, which you can see in the shape of the flower and the form of the inflorescence.

O. gracilis close up, showing the red markings

O. gracilis close up, showing the red markings

With  its distinctive red markings inside the flower, it’s beautiful in a rather weird way , partly due to the absence of green – the plant has no  chlorophyll at all – and partly because I can’t bring myself to like a plant that preys completely on something else. Its human equivalent must be the thief, the pimp, the drug dealer – I’ll come back to that.

A dry stem of broomrape - O. picridis or O. minor?

A dry stem of broomrape – O. picridis or O. minor?

Within a week or two, I’d found another broomrape, this time in the sand dunes, but all that remained was a dried flower stalk. I’ve since found another, very similar but equally dry, in the next village to mine. So, some detective work needed. I’ve narrowed  the main possibilities for these to two:  Orobanche minor, or O. picridis, since both were tall and slim, with small flowers, and near what looked like a Picris – a species of oxtongue with a small dandelion-like flower. They could be one of each – and O. minor is said to be found near the sea and also parasitises composites like Picris, as well as legumes.

This leads me to the difficulty of identifying broomrapes in general – they’re mostly in shades of yellow through to pink, most have a single spike of whitish flowers, and to make matters worse, most are variable in appearance depending on soil, location and host. But there is one main clue to note: they are usually pretty close to their host plant. This helped me identify the next broomrape I found, on the sauveplaine. There were a couple of small colonies, both next to, even growing through the leaves of their host plant, Eryngium campestre or field eryngo.

Orobanche amethystea just emerging

Orobanche amethystea just emerging

This is Orobanche amethystea, which parasitises a variety of plants, mostly umbellifers like Eryngium (members of the family now named Apiaceae).

O. amethystea growing through leaves of Eryngium

O. amethystea growing through leaves of Eryngium

Orobanche amethystea close up

Orobanche amethystea close up

What about the strange names for these blooms, with their echoes of violence? Broomrape comes from the Latin name for one species parasitic on broom – O. rapum-genistae – rapum (the Latin word for turnip) in this case signifying the root-swelling where the parasite has taken hold. Orobanche comes from orobus (vetch) and ancho (strangle).

I wondered how the life-cycle of Orobanche could work, given that it has to  find a host,  and that cross-pollination must be as rare as the plants. They often self-pollinate, and the flowering heads can each then produce  100,000 tiny seeds. These are the seeds from one of the dried plants – each seed is only a tenth of a millimetre across.

Orobanche and seeds

Orobanche and seeds

The seeds can lie dormant in the soil for years, until stimulated by chemicals from the roots of a living host plant (for more on the  social life of plants, see my post here).  The seed then germinates, sending a small rootlet towards its host root and boring in to the vascular tissue.  This creates a bulge or tuber on the root, from which the flower will eventually arise – after which the broomrape dies. While they are rare in Britain, and often protected, they are a significant problem for agriculture in other areas, principally dry regions such as North Africa and the Near East. Orobanche crenata parasitises broad beans, and it’s estimated that Egyptian farmers lose up to 40% of their crops to this predation. The tiny seeds are easily spread by animals and farm machinery, and the problems there, and in Morocco and Algeria, are increasing.  Farmers will have to pick the flowers before they set seed, and clean tractor tyres to contain the spread.

How to find the jazz in all that? Well, I’ve just been reading  So What, the superb biography of Miles Davis by John Szwed (who wrote the equally brilliant bio of Sun Ra, Space is the Place). Davis comes over as little more than a parasite in his relationships with non-musicians, especially with women.  And a thief and a pimp at times. He was so insecure, so dependent, so demanding, and without them he was cocaine-addled and dormant.  But there’s the life, and there’s the work, and my admiration for and love of the man’s music is undimmed by his portrayal.  Here’s something from just one of the revolutions Miles wrought in music, often, as here, with the help of his friend Gil Evans: the Birth of the Cool, and Moon Dreams.

Coming up next: They’re as alike as two peas – hang on, they are two peas

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Been there, dune that

I’d like to take you to the other patch I’ve chosen in which I’m going to try to list all the species of plants I find. Other patch? Yes, the first was in the previous post.  That was in the hills, this is by the sea, and already the comparison is showing me a lot about each habitat.  Here we are at Marseillan-plage:

The dunes of Marseillan-plage, looking west (promenade up on the left)

The dunes of Marseillan-plage, looking west (promenade up on the left)

The dunes towards the port on the east side - promenade now on the right of the image

The dunes towards the port on the east side – promenade now on the right of the image

The town of Marseillan is a very old port on the Étang de Thau, founded in the 6th century BCE by the Greeks; facing the Mediterranean its neighbour Marseillan-plage is – there are no other words for it – a brash new tourist resort, which has invested a great deal of money in the last year to become, well, even brasher. But it has a botanical jewel in its narrow system of dunes.

Jewel? Doesn’t it look just like a patch of dried-out weeds?  Look closer. There are at least two separate main ecosystems here, separated by the promenade between the town and the harbour: the dunes nearest the sea are the least stable, blown by wind and spray, and only a few species can take the conditions: Euphorbia paralias (sea spurge) which I blogged here, Elytrigia juncea (sand couch grass), and Ammophila arenaria (marram grass) are examples.  The Euphorbia can store water in its stems and fleshy leaves.

Elytrigia juncea - sand couch grass - Chiendent des sables

Elytrigia juncea – sand couch grass – Chiendent des sables

These are the shifting sands – dunes vives in French – pegged down by rows of fencing made of chestnut stakes. These are in place all along the coast, after the damage of a great storm in November 1982 awakened the authorities to the gradual erosion of the coastline by the prevailing east to west currents.

On the town side of the promenade and sheltered by it from the worst of the wind and salt spray, a much more diverse flora has established itself. Although the sand is infiltrated by seawater, there is a layer of fresh water within the sand which lies on top of the salt because it’s less dense, and a plant with roots deep enough to reach this layer can survive. Even so, the plants here in the arrière-dunes show even stronger adaptations to drought than on the sauveplaine. For example, this clump of Paronychia argentea has a low, dense growth habit, and refective silvery bracts round the flowers, creating its own shade underneath.

Paronychia argentea

Paronychia argentea

Many dune plants are covered in a thick downy coat of hairs, which both reflect heat and reduce evaporation, such as this Sea medick (Medicago marina), which is rarely seen away from the coast.

Sea medick - Medicago marina

Sea medick – Medicago marina

Others have leaves reduced to slender leaflets, such as Centaurea aspera (rough starthistle) and Anthemis maritimus.

Centaurea aspera - identified by its 3-spined bracts

Centaurea aspera – identified by its 3-spined bracts, and Anthemis in the background

One unexpected discovery was the dry stem of this broomrape. These plants are completely parasitic on other plants, and can often be identified by spotting the host plant nearby.  In this case the yellow composite is a clue to its probable identity as Orobanche minor (common broomrape), and this species is often found near the sea. The grass in the picture is Lagurus ovatus : hare’s tail or bunny-tail grass, or Queue-de-lièvre.

Broomrape - Orobanche minor? - and yellow composite which it may be parasitising

Broomrape – Orobanche minor? – and yellow composite which it may be parasitising

I’ve found a couple of other broomrapes recently: they’re stunning flowers and I’ll write a post about them soon.

At the foot of the landward side of the fixed dunes, just before the houses begin, the terrain is more fixed, the water is closer to the surface and perhaps some organic matter can accumulate to enrich the sand – at any rate, some plants here resemble those of further inland, or even those of gardens. For example, a stout Lavatera arborea (tree mallow) would grace any front yard, and the wild leeks (Allium ampeloprasum) are the same as those on the sauveplaine.

Lavatera arborea - tree mallow - at the foot of the arriere-dunes

Lavatera arborea – tree mallow – at the foot of the arriere-dunes

Allium ampeloprasum- wild leek - just opening in the dunes

Allium ampeloprasum- wild leek – just opening in the dunes

The Marseillan patch study is now up to 24 species – I’ll work on a list which I’ll set up on another page on the blog here, and keep updated. The close study of two very different areas is fascinating, and it’s showing me that the dune season is much more compressed, with some flowering seasons over before those in the hills have really started. The grasses in the two places are completely different – I’m trying to get a grip on identifying these.  And over the summer I expect to see the real dune specialists which flower most of the year, such as Anthemis, and others yet to be discovered. But the greatest wonder of the dunes is that very different habitats are found only metres apart, and so in ten minutes you can have a good lesson in ecology. I’ll be suggesting this as an important asset to the municipality – there’s been a lot of redevelopment in the town in the last year and I’d hate for this area, which is like a wild park in the centre of town, to be disturbed to lay drainage pipes or to build ice-cream stands. The rest of Marseillan-plage is concrete, with imported palm trees.

Here’s some music from a region I imagine to be as dry and sandy as the dunes. It’s from the album Jama Ko, by Bassekou Kouyate and Ngoni Ba, recorded in Bamako in Mali in 2012, and something I like very much indeed.  This track, Poye 2, also features the bluesman Taj Mahal, a longtime fan of Kouyate.

Coming up next: Close relations: how do you tell them apart?

 

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Filed under Allium, Anthemis, Centaurea, Euphorbia, Lagurus, Lavatera, Medicago, Orobanche, Paronychia