Physcomitrella patens

The moss Physcomitrella patens

The Physcomitrella patens gametophore ('moss plant') is the haploid organism that develops from a haploid spore that has one set of chromosomes. Image: With kind permission from the REM-Labor, University of Basel, Switzerland

Our object of interest is Physcomitrella patens ssp. patens, the spreading earthmoss. In the remainder of the text called 'moss' or 'Physcomitrella'. Together with the ferns (Pteridophyta) and the seed(-bearing) plants (Spermatophyta), mosses (Bryophyta) belong to the Embryophyta.

More images:

Life cycle of the moss Physcomitrella patens. Image: Ralf Reski. (please click to enlarge)

Whereas in seed plants the diploid spermatophore is dominant, in mosses this part belongs to the haploid gametophore. To learn about the life cycle of Physcomitrella click on the image to enlarge it.

Comparison of seed plants and mosses

Cauloid - Shoot
Phylloid - Leaf
Rhizoid - Root

Mosses, like seed plants, possess a (thin) cuticula, cellulose, stoma, chlorophyll a and b and carotenoids - they are land plants. However, they do neither have vascular bundles nor lignin.

Some interesting things about mosses

They can regenerate very well from every part of the plant. They can survive long times of dryness (up to 14 years), extreme cold (antarctica) and heat (70 to 110 degrees Celsius). They can live with only 0.1% of sun light (seed plants need at least 2%). (There is of course no single moss that possesses all this features.