The Plant DNA C-values Database (https://cvalues.science.kew.org/) is a comprehensive catalogue of C-value (nuclear DNA content, or in diploids, genome size) data for land plants and algae.
The database was created by Prof. Michael D. Bennett and Dr. Ilia J. Leitch of the Royal Botanic Gardens, Kew, UK.
In addition to the angiosperm dataset made available in 1997, the database has been expanded taxonomically several times and now includes data from pteridophytes (since 2000), gymnosperms (since 2001), bryophytes (since 2001), and algae (since 2004) (see (1) for update history).
(Note that each of these subset databases is cited individually as they may contain different sets of authors).
A similar Animal Genome Size Database was created in 2001 by Dr. T. Ryan Gregory of the University of Guelph, Canada.