Abstract
Seed mass and shape of grasses were analysed in a temperate flora
containing 178 and 26 species belonging to C3 and C4 photosynthetic
types respectively. The weedy character and the annual or perennial
status were also considered. On the basis of the seed traits studied,
three groups were distinguished: C4 grasses, annual C3 grasses of weedy
character and perennial non-weedy C3 grasses. The C4 group had more
isodiametric (same diameter in all directions) seed shape and lower
average seed mass than the C3 group. To our knowledge, this has not yet
been described for temperate C4 grasses and is certainly associated with
their preference for open habitats where competition for light is
small. Weedy annual C3 grasses had heavier and less isodiametric seeds
than C4 grasses did. These species are mostly specialized to establish
in the dense cover of perennial vegetation, and this ability
distinguishes them from the C4 group. Non-weedy perennial C3 species
possessed less isodiametric seeds than did C4 grasses, but did not
differ from weedy annual C3 grasses. As most alien C4 grasses
naturalized in Hungary are annuals with small, isodiametric seeds, these
traits are good candidates to be included in screening for potential
future invasives in open habitats.
Keywords
C4 grasses, photosynthetic types, seed ecology, seed slenderness, thousand-seed weight, weeds
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