Leaf size in mosses is structurally constrained by cell dimensions and genome size.

Area of Science:

• Plant Biology
• Ecology
• Bryology

Background:

• Leaf anatomy is crucial for plant ecology.
• While studied in tracheophytes, leaf size determinants in bryophytes (mosses) are less understood.
• Mosses exhibit small leaf sizes, necessitating specific anatomical investigations.

Purpose of the Study:

• To investigate the primary anatomical factors controlling leaf size in mosses.
• To explore the relationship between moss leaf anatomy, genome size, and ecological traits.
• To understand how mechanical support influences moss leaf size.

Main Methods:

• Measured cell and leaf dimensions, cell density, cell wall thickness, and midrib length in 287 moss species.
• Correlated anatomical traits with growth form and genome size.
• Analyzed relationships among these diverse traits.

Main Results:

• Moss leaf size positively correlated with cell size and negatively with cell density.
• Leaf size was strongly influenced by midrib length, with longest leaves having midribs reaching the apex.
• Genome size showed a positive correlation with cell and leaf size, particularly in acrocarpous mosses.

Conclusions:

• Moss leaf size is constrained by mechanical support from cell turgor and midrib structure.
• Genome size significantly impacts leaf size, with this effect amplified in acrocarpous mosses.
• Moss anatomy serves as a critical link connecting genome size to plant ecology.