Alpine meadow-grass (Poa alpina L.)
Plants have many ways to reproduce. Most grasses are either wind pollinated or self-pollinated and produce seed as a result of that pollination, including many of our most valuable food crops such as maize, wheat and rice. The pollination results in a sexual recombination of the genes coming both from the pollen donor and the mother plant. Such recombination can result in a fitness that is better or worse than that of the parental plants. In a changing environment it gives natural selection a chance to work and will eventually result in adaptation to new conditions.
Danish: Fjeld-rapgræs – Finnish: Tunturinurmikka – Icelandic: Fjallasveifgras – Norwegian: Fjellrapp – Swedish: Fjällgröe
Text and photos by Magnus Göransson.
Another strategy is to produce seeds without pollination, a phenomenon called apomixis. The benefit is that the offspring will be genetically identical to the mother plant, which is favourable in a stable environment. However, no genetic recombination occurs which makes it difficult to adapt to new environmental conditions.
Strategy of reproduction
Some arctic grass species have yet another strategy of reproduction. Instead of flowers, they develop bulblets on the panicle, which develop into plantlets which will form new plants once they reach contact with the soil. This is called pseudo-vivipary and the plants are pseudo-viviparous. The plantlets are genetically identical to the mother plant since no flower develops, and thereby no pollination occurs. As the mother plant is well adapted to the environment, so will the offspring be. It can further be an advantage in the harsh arctic growing conditions where the plantlets start photosynthesising even before they detach from the mother plant, giving them a head start. However, in a changing climate an exclusively vegetative reproduction can be a risky strategy as no new genetic diversity is formed, thereby reducing the adaptability to new conditions.
Poa alpina, the Alpine meadow-grass, has two forms, and three reproductive strategies: one pseudo-viviparous, forming little plantlets instead of flowers, and one flowering and seed-bearing form which is facultative apomictic, meaning it produces seeds both with and without pollination, sometimes on the same plant. This ensures that many offspring are genetic copies of the mother plant, and thus adapted to the local environment. A portion of the seed, however, will be a mix between two parental plants which could result in a better fitness, especially to changing conditions.
Grows on Svalbard
Alpine meadow-grass has a distribution throughout high latitudes and high altitudes in the Northern hemisphere. In the Nordic region it grows in northern regions of Finland, Sweden, Norway, and in Iceland. It grows as far north as Svalbard, where it is rare and red listed. The pseudo-viviparous form generally grows in moist conditions and in high altitudes, whereas the seed-bearing form grows in dryer conditions and even tolerates the desert-like conditions in the interior of Iceland, with less than 400 mm annual precipitation.
Poa alpina is a crop wild relative to Poa pratensis, the Kentucky Bluegrass, which is used as a fodder grass, but also widely used as lawn grass and in golf courses. The two species can hybridize. Perhaps a hardy drought tolerant grass from the Arctic could be a solution to more drought resistant golf courses in the future?
References:
Mossberg, B., Stenberg, L. 2018. Nordens flora. Bonnier fakta, Sweden.
Müntzing, A. 1966. Apomixis and sexuality in new material of Poa alpina from middle Sweden. Hereditas 54(3): 314-337.
Steiner, B. L., Armbruster, G. F. J., Scheepens, J. F., Stöcklin, J. 2012. Distribution of bulbil- and seed-producing plants of Poa alpina (Poaceae) and their growth and reproduction in common gardens suggest adaptation to different elevations. American Journal of Botany 99(12): 2035–2044.
