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UNIT II EVOLUTION AND DIVERSITY OF 59

Embryophyta – land plants Pan-Tracheophyta/ Polysporangiophytes

Tracheophytes s Liverworts Mosse s †† –vascular plants

gametophytic intercalary growth of sporophyte † = Extinct perine in wall pseudo- leafy (in some) sporophyte branched leptoids columella with multiple sporangia elaters in stomates-functional in hydroids photosynthetic gas exchange oil bodies sporophyte photosynthetic, nutritionally independent

aerial sporophyte axis stomates-functional in sporangium dehiscence

antheridium parenchyma cuticle sporophyte/ (alternation of generations) A Embryophyta – land plants Pan-Tracheophyta/ Polysporangiophytes

Tracheophytes Hornwort s Liverworts Mosse s †† –vascular plants gametophyte gametophytic leaves leafy (in some) perine in spore wall elaters sporophyte photosynthetic, in sporangium leptoids † = Extinct nutritionally independent oil bodies hydroids intercalary growth of sporophyte sporophyte branched with multiple sporangia pseudo-elaters sporophyte photosynthetic, nutritionally independent columella aerial sporophyte axis (independently derived in and ) stomates-functional in sporangium dehiscence stomates-functional in photosynthetic gas exchange [alternative possibilities (among others)] stomates-functional in sporangium dehiscence archegonium antheridium parenchyma B cuticle sporophyte/embryo (alternation of generations)

Figure 3.6 A. One hypothesis of relationships of the land plants (Embryophyta), with major apomorphies indicated. After Qiu et al. (1997), some apomorphies after Bremer (1985), Mishler and Churchill (1985), and Mishler et al. (1994). B. One of many alternative hypothesis, this showing a monophyletic bryophytes (after Puttick et al. 2018), with different scenarios for the evolution of some characters. Note that a photosynthetic, nutritionally independent sporophyte evolves twice, and stomate evolution could involve a novel (for the bryophytes alone) or intermediate (for all ) function in sporangium dehiscence.