“…Because genetic individuals in such species are not stationary, they experience spatial variation in environmental characteristics. These features of clonal plant biology have led ecologists to describe clonal growth as a movement process (Bell 1984, Sutherland and Stillman 1988, Cain 1990, Callaghan et al 1990, Klimes 1992 and to investigate empirically the morphological response of plants to spatial variation in biotic and abiotic components of their environment (McIntyre 1967, Ginzo and Lovell 1973, Turkington and Harper 1979, Penalosa 1983, Salzman 1985, Grime et al 1986, Slade and Hutchings 1987a, b, Kelly 1990, see also the recent review by Hutchings and de Kroon 1994). Some clonal plant species decrease rhizome or stolon internode lengths and/or increase the frequency of branching in favorable environments (Ashmun and Pitelka 1984, Schmid 1986, Mitchell and Woodward 1988, de Kroon and Knops 1990, Alpert 1991, and references cited in Table 1 in Sutherland and Stillman 1988).…”