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J. HESLOP-HARRISON
Since the earlier work of Gregor and his collaborators on Plantago
maritima, ecoclinal variation has been described in several herbaceous
species. Bocher’s investigations of Prunella vulgaris (1945, 1949) have
involved comparative cultivation of large numbers of population
samples from throughout the species range, both in standird and varied
environments. He considers that units worthy of being termed ecotypes
occur within the species, the principal ones being associated with montane-boreal habitats, and with dry, medium dry, wet and shaded soils in
lowland habitats. However, “in P. vulgaris there is continuous variation,
for which reason the ecotypes . . . represent the most frequent character
combinations in the different types of habitat. A large number of biotypes or races may not be conformable to the ecotype system, because
in respect of one or more characters they do not agree with the ideal
combination (the most characteristic features of the ecotypes).” Bbcher
refers to the ecotypes within P. vulgaris as theoretical concepts, since
they are, essentially, “composed of ranges within a whole series of
continuous or almost continuous character gradients or clines.” His
position is thus very close to that of Gregor.
Bocher and co-workers have also given evidence of ecoclinal variation
in Plantago coronopus (Bocher et al., 1953, 1955). The diploid complex
represented by P. coronopus L. and P. macrorhiza Poir. forms a very
variable series of populations around the Atlantic and Mediterranean
seaboards of Europe. Comparison of population samples from throughout the range in cultivation led to the conclusion that the adaptive
trends were best expressed “as through a number of clines running from
the north to the south in Europe. Strains of southern origin deviate from
those from the north by often being of greater size, with more ascending
leaves and scapes, wider leaf-rhachis and longer spikes. They further
seem to be more resistant to drought”. Dwarf races occurring in the
north-west on exposed rocks and cliffs were considered to constitute a
race distinct enough to be called an ecotype, which, however, differed
from another similar ecotype on sea cliffs in southern Scandinavia.
Like P. maritima, P. coronopzls shows great local variation in Europe,
and it is likely that major clinal trends suspected by Bocher et al. overlie
local patterns of ecotypic and ecoclinal variation comparable to those described by Gregor for the former species in the British Isles (Dodds, 1953).
Studies on the phenotypic variation of wild populations have often
revealed very distinct clinal trends related to climatic gradients (e.g.
Alnus glutinosa, McVean, 1953; Melampyrum pratense, Smith, 1963),
and although much of the observed variation may well be in consequence of plastic modification, there seems little doubt that some will be
genotypically based. Indeed, the view of Stebbins (1950) that “it is
likely that most species with a continuous range that included more
J. HESLOP-HARRISON
Since the earlier work of Gregor and his collaborators on Plantago
maritima, ecoclinal variation has been described in several herbaceous
species. Bocher’s investigations of Prunella vulgaris (1945, 1949) have
involved comparative cultivation of large numbers of population
samples from throughout the species range, both in standird and varied
environments. He considers that units worthy of being termed ecotypes
occur within the species, the principal ones being associated with montane-boreal habitats, and with dry, medium dry, wet and shaded soils in
lowland habitats. However, “in P. vulgaris there is continuous variation,
for which reason the ecotypes . . . represent the most frequent character
combinations in the different types of habitat. A large number of biotypes or races may not be conformable to the ecotype system, because
in respect of one or more characters they do not agree with the ideal
combination (the most characteristic features of the ecotypes).” Bbcher
refers to the ecotypes within P. vulgaris as theoretical concepts, since
they are, essentially, “composed of ranges within a whole series of
continuous or almost continuous character gradients or clines.” His
position is thus very close to that of Gregor.
Bocher and co-workers have also given evidence of ecoclinal variation
in Plantago coronopus (Bocher et al., 1953, 1955). The diploid complex
represented by P. coronopus L. and P. macrorhiza Poir. forms a very
variable series of populations around the Atlantic and Mediterranean
seaboards of Europe. Comparison of population samples from throughout the range in cultivation led to the conclusion that the adaptive
trends were best expressed “as through a number of clines running from
the north to the south in Europe. Strains of southern origin deviate from
those from the north by often being of greater size, with more ascending
leaves and scapes, wider leaf-rhachis and longer spikes. They further
seem to be more resistant to drought”. Dwarf races occurring in the
north-west on exposed rocks and cliffs were considered to constitute a
race distinct enough to be called an ecotype, which, however, differed
from another similar ecotype on sea cliffs in southern Scandinavia.
Like P. maritima, P. coronopzls shows great local variation in Europe,
and it is likely that major clinal trends suspected by Bocher et al. overlie
local patterns of ecotypic and ecoclinal variation comparable to those described by Gregor for the former species in the British Isles (Dodds, 1953).
Studies on the phenotypic variation of wild populations have often
revealed very distinct clinal trends related to climatic gradients (e.g.
Alnus glutinosa, McVean, 1953; Melampyrum pratense, Smith, 1963),
and although much of the observed variation may well be in consequence of plastic modification, there seems little doubt that some will be
genotypically based. Indeed, the view of Stebbins (1950) that “it is
likely that most species with a continuous range that included more