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.
