UNIT II EVOLUTION AND DIVERSITY OF PLANTS 59
Embryophyta – land plants Pan-Tracheophyta/ Polysporangiophytes
Tracheophytes Hornwort s Liverworts Mosse s †† –vascular plants
gametophytic intercalary growth leaves of sporophyte † = Extinct perine in spore wall gametophyte pseudo-elaters leafy (in some) sporophyte branched leptoids columella with multiple sporangia elaters in stomates-functional in sporangium hydroids photosynthetic gas exchange oil bodies sporophyte photosynthetic, nutritionally independent
aerial sporophyte axis stomates-functional in sporangium dehiscence
archegonium antheridium parenchyma cuticle sporophyte/embryo (alternation of generations) A Embryophyta – land plants Bryophytes 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 mosses and hornworts) 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 embryophytes) function in sporangium dehiscence.