Reproductive phenology in the leafy hepatic Lophozia silvicola Buch in southern Finland
2005
Laaka-Lindberg, Sanna
Reproductive phenology was described in the leafy dioecious hepatic Lophozia silvicola Buch during three successive growing seasons in an old-growth forest population in southern Finland. The sequence of phenological events was quantified by a maturity index M ᵢ, which was calculated on the basis of the rankings of the developmental stages and the numbers of individual shoots in each stage. The developmental cycle of antheridia was correlated with the temperature during the growing season, with maturation from July to August. Gametangia maturation from initials to gametangia dehiscence takes about 10 months including a probable pause during winter. Antheridia in early developmental stages were present in the population under study throughout the growing season. The timing of the developmental cycle of archegonia varied among years. Fertilization was estimated to occur in early to mid-summer on the basis of the presence of dehisced antheridia and the subsequent emergence of 'swollen venter' archegonia. Maturation of archegonia and the proportion of sporophyte-bearing shoots were correlated with mean rainfall and relative humidity during the week preceding each sampling. Total shoot number per sample, an indication of population density, was correlated with numbers and proportions of females and sporophyte-bearing shoots in the samples. The proportion of sex-expressing shoots in the population was on average 26%. The proportion of females was on average 8%, while the proportion of males was 17%, the difference between them being significant. The female to male sex ratio varied between the samples, with a mean of 0.61 indicating male-biased overall sex ratio in the population studied.
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