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Simplified phylograms illustrating the distribution of intercellular spaces and stomata in the major lineages at the base of the land plant tree of life: (a) liverworts (gametophyte and sporophyte generations); (b) mosses (sporophyte only); (c) hornworts (gametophyte and sporophyte generations). This underlines the likely multiple evolution of both features. 
Stomata present, 
Stomata absent, 
Stomata +/−, 
ICSs present, 
ICSs absent, 
ICSs presence/absence not known.
