Growth Habit and Mechanical Architecture of the Sand Dune‐adapted Climber Clematis flammula var. maritima L.

Will the real clematis please stand up?

Any paper that, without contrivance or irony, cites Charles Darwin is surely worth a closer look. Darwin was typical of his time in pursuing many interests in science, one of which was climbing plants. This is the subject of investigation by Isnard et al. (Montpellier, France and Frieberg, Germany, pp. 407-417). The plant in question is Clematis flammula, var maritima, which inhabits sand dunes in the Mediterranean region, an atypical habitat for a lianoid climber. Three types of stem are described. There is an extensive underground network of perennial stems; these give rise to upright stems which extend to form the lianoid climbing stems. However, other plants on which to climb are very scarce and thus the clematis stems cling together to form trellis-like structures up to 40 cm tall. The question then is whether this variety exhibits any differences from the biomechanical features of more typical climbers: �juvenile� stems that are relatively stiff and self-supporting which act as �searchers� and then extend and branch to form climbing stems which are much more pliant and flexible and thus not self-supporting. Surprisingly, the authors found little apparent adaptation, either in biomechanical properties or in internal anatomy, to this particular habitat. The early upright stems seemed, if anything, slightly less stiff than the juvenile stems of typical climbers and the lianoid stems were as flexible as those of typical climbers. However, the initial upright stems do exhibit more stiffness at their bases and they are also effectively stiffened by being �rooted� into the sand by the underground perennial stems. The authors propose that it is these underground perennial stems that provide a stabilizing feature in a mobile habitat such as sand, and suggest that climbers of this type may have a general use as stabilizers of sand dune systems that are in danger of degradation.