Global rheophytes data set: angiosperms and gymnosperms

Area of Science:

• Botany
• Ecology
• Evolutionary Biology

Background:

• Rheophytes are flood-tolerant plants adapted to riverine environments.
• The last global census of rheophytes was over 35 years ago, necessitating an update.
• Understanding rheophyte diversity is crucial for conservation and ecological studies.

Purpose of the Study:

• To review key aspects of rheophytism, including morphology, genetics, distribution, and evolution.
• To create an updated global checklist of rheophyte taxa in seed plants (gymnosperms and angiosperms).
• To map the geographical distribution and richness of rheophytes and analyze their placement in angiosperm phylogeny.

Main Methods:

• Comprehensive literature review of peer-reviewed articles, theses, dissertations, reports, books, and floras.
• Compilation of a dataset of rheophyte taxa from global sources.
• Phylogenetic analysis and mapping of geographical distribution using compiled data.

Main Results:

• A dataset of 1,372 rheophyte taxa was compiled: 4 in gymnosperms (Podocarpaceae) and 1,368 in angiosperms (114 families, 508 genera).
• The majority of angiosperm rheophytes are eudicots (72.81%), with significant representation from monocots (25.73%).
• High richness of rheophytes is concentrated in tropical and subtropical regions, notably southern Mexico, southern China, Borneo, and Australia; gymnosperm rheophytes are restricted to New Caledonia and Tasmania.

Conclusions:

• This study provides the most comprehensive update on rheophyte diversity and distribution to date.
• Rheophytism is widespread across angiosperm phylogeny, with at least 80 families harboring obligate rheophytes.
• The findings underscore the importance of rheophytes as a unique ecological group and highlight areas of high biodiversity requiring conservation attention.