Hunting Ceropegia fusca on Gran Canaria

Habitat, nursery/collection and show tours.
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Bassman
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Hunting Ceropegia fusca on Gran Canaria

Post by Bassman » Sun Sep 13, 2009 4:25 pm

This article was first published in the March 2000 journal of the BCSS. It is reproduced here by kind permission of the editor.

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Ceropegia fusca in habitat in Fataga Valley, Gran canaria

It is not always necessary to travel to remote parts of the world in order to see succulents in the wild. If you are prepared to do some research in advance, and are adventurous enough to do a little exploring when you get there, it is surprising what you can find, even in popular package holiday destinations.

In November 1997, I visited Gran Canaria accompanied by Steve Brayshaw and newspaper editor and friend, Richard Butt. The main purpose of the trip was for a well-earned holiday, neither of my companions being particularly interested in succulent plants. However, I knew the island to be the habitat of Ceropegia fusca Bolle, a plant I had grown almost twenty years earlier but had lost after a heater failure reduced it to mush on a bitterly cold January night. Having been unable to find it since, I had decided well before leaving the UK that I couldn’t miss the opportunity to hunt for this interesting asclepiad in its native surroundings.

Known to the Spanish as “cardoncillo,” Ceropegia fusca is one of the Canarian stick-like species first described by the German collector Carl August Bolle in 1861. However, I should mention that the Canarian ceropegias have undergone a recent taxonomic overhaul. In the December 1998 edition of Asklepios, Gordon Rowley proposed that they be reduced to a single species, C. dichotoma Haworth, with three subspecies, according to the following key:

A. Stems and flowers purplish, corolla 2-3cm tall, broad tipped.
ssp. fusca

AA. Stems some shade of green and flowers yellow. Corolla 3-4cm tall, tapered at the tip.

B. Flowers in clusters of 10-50
ssp. krainzii

BB. Flowers in clusters of 2-8
ssp. dichotoma.

If one accepts this classification, the plant should be more correctly referred to as Ceropegia dichotoma Haworth ssp. fusca (Bolle) Rowley, but I have retained the earlier name here purely for convenience. In the Bramwells’ Wild Flowers of the Canary Islands, the authors state that C. fusca can also be found at Medano on Tenerife, however unlike the white stemmed form discussed here, the plants on Tenerife are reported as brown stemmed. On the other hand, C. dichotoma, also from Tenerife, has stems that are morphologically similar but that are distinctively green. Clearly this is a variable taxon with some room for debate as to how it should be treated.

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Euphorbia canariensis growing in the Fataga Valley, Gran Canaria

Lying in the Atlantic Ocean approximately 100 kilometres west of Morocco, the Canaries enjoy year-round sunshine, hence their popularity as a holiday retreat. On Gran Canaria itself, one of the archipelago’s southernmost islands, the daytime temperature in the coastal area of Maspalomas where we were staying was seldom below 30C.

In common with its neighbours, Gran Canaria was formed as a result of volcanic activity. Over the last 20 million years or so it has been subjected to a series of alternating desert and glacial cycles, the resulting erosion forging deep valleys called “barrancos” arranged around a central volcanic core, rather like the spokes of a wheel. This has given the island its peculiar ridged cone shape and it is in one of these valleys, the Barranco de Fataga in the south, that Ceropegia fusca can be found.

On the morning of the trip, armed with a map of the island, we set off in our hired car from Maspalomas travelling north towards the town of Fataga. We were soon thankful we had chosen a car with air conditioning; exposed to the hot, dry winds coming from the Sahara, the Fataga Valley is an extremely arid place, receiving on average only 150-250mm of rain per year. In fact, we were told by one of the locals that some parts of the island hadn’t had rain for 3 years.

As we drove into the valley, we stopped a couple of times in what looked like promising locations. But after scrambling around among the baking rocks for half an hour we found only the ubiquitous Euphorbia canariensis, Senecio kleinia, an abundant shrubby euphorbia which I took to be E. obtusifolia and the very occasional aeonium, probably A. manriquorum.

Resuming our journey, the terrain became distinctly rockier and more mountainous as we climbed towards the island’s interior. Lacking an altimeter, I could only make a rough estimate of our altitude from the map, but I guessed it was when we had reached around 300m, or about 5 kilometres into the valley, that I caught my first sight of Ceropegia fusca, its greyish-white stems standing out quite clearly against the rock-strewn hillsides.

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C. fusca growing among shrubby Euphorbia balsamifera

At first, getting to the plants was quite treacherous, as many of them were growing on steep slopes in rather loose scree that made conditions underfoot difficult. But once you’d “got your eye in” the plants were everywhere. Despite its CITES status and being restricted to the Fataga Valley, Ceropegia fusca is locally quite plentiful with lots of regeneration evident. I did not observe any signs of damage by insects or grazing animals, so the plant appears to have few if any natural enemies.

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Ceropegia fusca in habitat

Resembling jointed, skeletal fingers, the plant forms clusters of anything up to two dozen erect stems approximately 1cm thick and around 30-40cm tall, branching from the base. Juvenile plants are darker in colour, only assuming the distinctive glaucous appearance in maturity. However, the new growth even on older plants is a dark chocolate brown, very slender and brittle and easily detached at the slightest suggestion of rough handling. At the growing point of each stem there is a single pair of thin, short-lived leaves.

This is the form that I had encountered in cultivation and with which I was familiar, however in age, Ceropegia fusca takes on a rather different appearance, at least in habitat. As the stems thicken, they become less erect and rather more procumbent and as the afternoon wore on, we saw some monster specimens approaching a meter across in some of the more remote off-road areas. Their fat, sausage-like stems, up to 3cm thick and brilliantly chalky-white, formed sprawling clumps that seemed to prefer growing in the shade of rocks or taller plants of E. obtusifolia or E. canariensis. But as Murphy’s Law would have it, we did not find the best specimens until I had only two or three shots left in the camera and with the light diminishing fast.

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Some of the plants we found were in flower. Having no discernible scent, these are borne in clusters of typically two or three, occasionally as many as six or eight, from a node towards the tip of a stem. The corolla tube is elongated and is reddish in colour with a yellow throat. As is typical of the genus, the five corolla lobes are fused together at the tip forming a lantern-like structure and in common with other asclepiads, the plant’s fruit is a pair of elongated follicles or “horns”. I did not observe any insects visiting the flowers, so I was not able to guess what the pollinating agent might be.

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A particulary fine specimen of C. fusca

Judging by the number of seed horns we saw, the main flowering period was probably over and on one of the larger plants, I counted over a dozen pairs of follicles, so I didn’t feel too bad about collecting a single pair. Clearly, the seed dispersal mechanism is by wind; one of the horns opened in our chalet over the next few days, splitting longitudinally to release a mass of seeds tufted at one end, resembling those of Pachypodium.

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Detail of flower and seed horns

The germination rate of the collected seed was excellent and in a single season, the seedlings made attractive plants of two or three stems, between 10cm and 15cm tall. At first, the seedlings are the same chocolate brown as the newer growth on older plants, however they soon take on the appearance of mature plants after the first year or so, slowly whitening with age. They do seem to be sensitive to excess moisture, though; too much water and they quickly keel over and rot at the base. Having seen the aridity of their habitat, this is perhaps not surprising. The growing regime is unremarkable, using a medium of one third peat-based compost, one third Perlite and one third of coarse grit and sand mixture. The nighttime temperature is rarely below 13C.

Back in the Fataga Valley, by late afternoon the light had faded to the point at which photography had become impossible, so we decided to return to the car and head back to our base in Maspalomas. I shall not readily forget the thrill of finding a wild plant for the first time; this had been my first experience of hunting plants in habitat and I would thoroughly recommend it to anyone.

References:

FOGGI,B. (1997) Flowers of Canary Islands, p3, Casa Editrice Bonechi, Firenze, Italy
STEPHENSON, R (1994) Flighthopper's Guide to the Succulent Wealth of Gran Canaria, Brit. Cact. Succ. J 12(1): 21-25
BRAMWELL, D & BRAMWELL, Z., (1984) Wild Flowers Of the Canary Islands, Stanley Thornes Publishers Ltd., London
Last edited by Bassman on Fri May 07, 2010 12:31 am, edited 1 time in total.
Carl Howard
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Trevor
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Re: Hunting Ceropegia fusca on Gran Canaria

Post by Trevor » Wed Sep 16, 2009 11:55 am

Interesting reading....thanks for sharing it. I've raised a number of C. fusca from seed and the seedlings grow well, but they seem to come to a grinding halt in the second year, showing very little progress if any. Now that spring is coming here, and after reading this, I might try and put them in a hotter part of the greenhouse, maybe that'll get them going ??
Trevor
With a 'Downunder' collection of Cacti and Succulents in Melbourne, Australia.
Bassman
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Re: Hunting Ceropegia fusca on Gran Canaria

Post by Bassman » Wed Sep 16, 2009 4:42 pm

Hi Trevor

I think they'll appreciate all the warmth you can give them and they can tolerate being dry for a remarkable length of time. You can perhaps just about see from the first photograph how shrivelled many of the stems are. Gran Canaria is often subjected to a sirocco (called locally "la calima") which is a hot, dry, dust-laden wind that blows up from the Sahara so in habitat, temperatures of 40C are not that uncommon. Mine tend to grow mainly in our summertime but flower all year round, albeit much less frequently in our winter. Those in habitat were flowering in November, which is technically winter in the Canaries (though not that you'd notice from the heat! :-) )

Carl
Carl Howard
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kaowinston
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Re: Hunting Ceropegia fusca on Gran Canaria

Post by kaowinston » Fri Sep 25, 2009 10:10 pm

Hello Carl

Great photos! Never heard of them before. So this is an education, and they are certainly different. Thanks.
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