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Citrullus colocynthis, Cucurbitaceae

Native and introduced plants of Lanzarote

While on holiday in Lanzarote, in the super interesting area of the world known as Macaronesia, I have had a chance to observe a refreshing variety of subtropical, tropical and xeric vegetation which in Scotland I could only find under glass, if even. I guess whoever really likes plants can only be twice as excited about going on holiday somewhere far and different, as being in a different country can feel like being in a huge and exotic botanical wonderland, or at least that’s how I feel!

To start this series about the plants I have recorded there I have a chosen a wild Mediterranean Cucurbitacea, as I have childhood memories of exploring another island, in Croatia, and finding a squirting cucumber, Ecballium elaterium, which I had only seen in books before. The same happened when I was exploring the southern coast of Lanzarote, with its arid dunes and gullies, and I found this vine known with a variety of names around the Mediterranean and the Middle East, but locally known as cohombrillo melonero, the bitter apple, or desert gourd. Growing on the summit of a sandy and rocky promontory, exposed to strong winds high in salinity and sun radiations year-round, two of these plants alone still managed to thrive thanks to their successful adaptations. The long and fleshy taproot absorbs and stores any accessible ground water resulting from the winter rains, which can be quite scarce in the southern part of the island, while the leaves are reduced in size and more deeply divided if compared to those of the domestic watermelon, Citrullus lanatus.

The fruit, the size of a large walnut, contains a great number of small brown seeds which are edible, and can be ground into flour or pressed for oil. For this reason the plant has been cultivated since historical times on a small scale in countries with suitable conditions and low rainfall, and is still in cultivation today. Both the extremely bitter fruit and the seeds have been used for their laxative, emetic and abortive properties for just as long.

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Launaea arborescens, Asteraceae & Cuscuta approximata, Convolvulaceae

During the first few days of my holiday, while walking to and back from the beach, I noticed something bright yellow growing shapelessly in an arid field, far below my position. It wasn’t the sort of place I could climb down to in flip flops, so when I remembered to bring shoes I eventually got closer, and realised that was actually a battlefield.

The yellow masses I couldn’t really make out clearly from a distance turned out to be large, sprawling colonies of alfalfa dodder, which I must have missed when reading about the endemic flora of Lanzarote and the Canary Islands, as I really didn’t expect to find here the most sizeable example of this species I ever observed in person. This parasitic plant from the morning glory and sweet potato family is widespread through Europe, Asia and North America, and its common name refers to its habit of infesting alfalfa (Medicago sativa) fields, but where I observed it, its preferred host is locally known as aulaga, a round, spiny and intricate shrub dotted with tiny yellow dandelion-like flowers and white, fluffy seed heads with the pappus typical of Asteraceae. Aulaga is a predominant native species in the Canary Islands, but is present in most parts of Macaronesia, NW Africa and to a lesser extent in Mediterranean southern Spain, always in association with low, open shrubland in arid, nutritionally poor soils, often close to the shore.

It looks like the adaptations this species developed to fend off herbivorous predation and thrive in an hostile environment prove congenial for the parasitic dodder as the perfect rigid scaffolding for three-dimensional growth. I am not sure whether an individual aulaga plant stands a chance at survival as dodder starts spreading through its green, succulent parts, but the great number of small, wind-dispersed seeds it produces, even while being attacked, ensure reproduction. I didn’t see any more dodder anywhere else I went, so I guess it tends to spread slowly and locally there, creating segregated colonies of a few individuals.

Bonus: I saw a couple of prickly aulaga bushes rolling around pushed by the wind like tumbleweeds, and their shape made them quite effective at that, but the plant doesn’t have a mechanism which severs the stem from the root system to free the body, as it happens in other tumbleweeds, so it was probably accidental.