Conclusions
Sexual reproduction is indispensable
The ultimate criterion for judging a plant's success, or the contribution of any character to that success, is the number of offspring it leaves. In this respect plants at high altitudes do not differ from others, and it is obvious that sexual reproduction cannot be abandoned in the cold. On the contrary, alpine vegetation is famous for the color and abundance of its flowers. The necessity to expand the range of a plant and to colonize new sites by dispersed seeds is a further reason why sex, inseparably linked to seed production, is indispensable for alpine plants.
Reproduction is constrained manifold
- Most important, growth is slow and alpine species usually take a long time to get mature.
- When finally plants are flowering, pollinators may be scarce and their availability may limit sexual reproduction.
- After pollination, unpredictable weather conditions may interrupt the development of seeds.
- Time until the first snow may be too short for seed ripening.
Germination and establishment are risky
Lifetime seed production of alpine species is normally high, but many seeds are lost during dispersal. Germination success is low, seedling mortality is high and outside of protected "safe sites", the establishment of a plant usually fails.
Alpine plants developed a variety of strategies to overcome these restrictions. Particularly, vegetative reproduction is a complement to sex in the cold, however without being able to replace it. Clonal plants are the topic of the following lesson.
Further reading
Part of this unit has been extracted from Körner Ch (2003) Alpine Plant Life: functional plant ecology of high mountain ecosystems. Springer, Berlin. Chapter 16: Plant reproduction, pp 258-278. The only available and up to date review on alpine plant reproduction.
Müller H (1881) Alpenblumen, ihre Befruchtung durch Insekten und ihre Anpassungen an dieselben. Leipzig. Still a valuable source of information on alpine plant reproduction. (German)
Stöcklin J, Bäumler E (1996) Seed rain, seedling establishment and clonal growth strategies on a glacier foreland. J Veg Sci 7:45-56. A case study from the Swiss Alps.
Acknowledgements
Glossary
- agamospermy
- The formation of seeds without sexual reproduction. The seeds are genetically identical to the mother plant.
- heterostyly
- The coexistence of genetically controlled hermaphrodite flowers with different style lengths, and usually with reciprocal anther positions.
- self-incompatibility
- The inability of a fertile hermaphrodite seed plant to produce zygotes after self-pollination. A mechanism ensuring outbreeding.
