Large clones on cliff faces: expanding by rhizomes through crevices.

BACKGROUND AND AIMS Large clones of rhizomatous plants are found in many habitats, but little is known about whether such clones also occur on cliff faces where environmental conditions are extremely harsh and heterogeneous. METHODS Using molecular (intersimple sequence repeat, ISSR) markers, the genotypic composition of a cliff-face population of Oxyria sinensis in Sichuan, China, was investigated. KEY RESULTS The 98 O. sinensis ramets sampled belonged to 12 different genotypes (clones). The three most frequent clones were represented with 45, 22 and 12 ramets, respectively; the remaining nine were represented with only one to five ramets. The three largest clones spanned at least 2.7 m in the vertical direction and 4.6-6.9 m in the horizontal direction on the cliff face. CONCLUSIONS On the cliff face, large clones of O. sinensis are formed by rhizomes growing along the crevices. Expansion by rhizomes may help O. sinensis to exploit the patchy resources and support establishment and growth of new ramets. Moreover, rooted ramets connected by rhizomes may effectively reduce the susceptibility of O. sinensis to rock fall and erosion and thus greatly improve the chances for long-term survival. The multi-clone structure indicates that sexual reproduction is also important for the long-term persistence of O. sinensis populations on cliffs.