No choice: seeds and stolons are both necessary for population growth: Geum reptans

Geum reptans is a perennial plant from alpine screes and moraines living above 2300 m up to 3800 m in the Alps, the Karpates, and the Illyric mountains. The plant reproduces sexually by seeds and vegetatively by rosettes produced at the end of long, slender stolons.

Growth of G. reptans is slow, first reproduction on moraines is only after 5-10 years. Adults do not reproduce every year and the overall frequency of reproducing adults is low (c. 7 %). Germination rate of seeds at natural sites is between 0.7 and 2.4 % (data from 2 years in two populations). Clonal establishment of new plants is much higher, between 53 and 74 %. However, because of the much higher number of seeds produced both reproductive modes are contributing equally to population growth.

life cycle
1 - Life cycle

Predicted population growth rates of 2 populations during a period of three years varied between 0.99 (stable) and 1.07 (moderate population growth). Interestingly both reproductive modes are necessary to maintain populations in the long term.

In a molecular study it was found that in spite of the highly fragmented alpine landscape genetic differentiation among populations of Geum reptans was not particularly high. At least within the same region there is considerable gene flow among populations, over larger distances probably mainly by wind-dispersed seeds.

The observed level of genetic diversity in populations of G. reptans is similar to lowland species and the molecular data confirms that recruitment from seedlings in this species is more frequent than commonly suggested for clonal alpine plants.

Life cycle scheme
2 - Life cycle scheme. Numbers are stage specific transition probabilities or seedling and vegetative rosette production on a 1-year basis.