A. Telenius et P. Torstensson, Seed type and seed size variation in the heteromorphic saltmarsh annual Spergularia salina along the coast of Sweden, PLANT BIO, 1(5), 1999, pp. 585-593
We investigated habitat characteristics, seed type and seed size Variation
between and within 41 populations of the heteromorphic saltmarsh annual Spe
rgularia salina. 95% of the investigated populations were truly heteromorph
ic regarding unwinged or winged seeds but either of the seed types could do
minate in individual populations. 39% of all seed capsules contained mixed
seed types. in 43% of capsules the seeds were exclusively unwinged, and in
18% only winged seeds were found. In a closer survey in one of the populati
ons (at Tullgarn, 58 degrees 50'N, 17 degrees 37'E), albeit predominantly h
eteromorphic, again capsules either contained mostly unwinged or winged see
ds: 59% of the capsules had mixed contents, 21% contained exclusively unwin
ged seeds, and 21% produced only winged seeds. Seed weight varied up to 10-
fold, with an overall mean of 77.2 mu g. 27% of this variation was due to v
ariation among populations, 52% was explained by Variation between individu
als, and 21% was due to Variation within individuals. Seed weight was posit
ively correlated with the frequency of winged seeds per capsule, especially
within populations, and negatively correlated to seed number. The frequenc
y of winged seeds in each capsule and seed weight was positively correlated
with population density both between and within populations.