<P> A 1997 proposed phylogenetic tree of Plantae, after Kenrick and Crane, is as follows, with modification to the Pteridophyta from Smith et al . The Prasinophyceae are a paraphyletic assemblage of early diverging green algal lineages, but are treated as a group outside the Chlorophyta: later authors have not followed this suggestion . </P> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Prasinophyceae (micromonads) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Streptobionta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Embryophytes </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Stomatophytes </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Polysporangiates </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Tracheophytes </Td> <Td> <Table> <Tr> <Td> Eutracheophytes </Td> <Td> <Table> <Tr> <Td> Euphyllophytina </Td> <Td> <Table> <Tr> <Td> Lignophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Spermatophytes (seed plants) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Progymnospermophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> Pteridophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Pteridopsida (true ferns) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Marattiopsida </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Equisetopsida (horsetails) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Psilotopsida (whisk ferns & adders' - tongues) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Cladoxylopsida † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> Lycophytina </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Lycopodiophyta </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Zosterophyllophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Rhyniophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Aglaophyton † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Horneophytopsida † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Bryophyta (mosses) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Anthocerotophyta (hornworts) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Marchantiophyta (liverworts) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Charophyta </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Chlorophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Trebouxiophyceae (Pleurastrophyceae) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Chlorophyceae </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Ulvophyceae </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Prasinophyceae (micromonads) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Streptobionta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Embryophytes </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Stomatophytes </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Polysporangiates </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Tracheophytes </Td> <Td> <Table> <Tr> <Td> Eutracheophytes </Td> <Td> <Table> <Tr> <Td> Euphyllophytina </Td> <Td> <Table> <Tr> <Td> Lignophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Spermatophytes (seed plants) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Progymnospermophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> Pteridophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Pteridopsida (true ferns) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Marattiopsida </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Equisetopsida (horsetails) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Psilotopsida (whisk ferns & adders' - tongues) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Cladoxylopsida † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> Lycophytina </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Lycopodiophyta </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Zosterophyllophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Rhyniophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Aglaophyton † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Horneophytopsida † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Bryophyta (mosses) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Anthocerotophyta (hornworts) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Marchantiophyta (liverworts) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Charophyta </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Chlorophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Trebouxiophyceae (Pleurastrophyceae) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Chlorophyceae </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Ulvophyceae </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Td> </Td> <Td> <P> Prasinophyceae (micromonads) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Streptobionta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Embryophytes </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Stomatophytes </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Polysporangiates </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Tracheophytes </Td> <Td> <Table> <Tr> <Td> Eutracheophytes </Td> <Td> <Table> <Tr> <Td> Euphyllophytina </Td> <Td> <Table> <Tr> <Td> Lignophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Spermatophytes (seed plants) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Progymnospermophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> Pteridophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Pteridopsida (true ferns) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Marattiopsida </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Equisetopsida (horsetails) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Psilotopsida (whisk ferns & adders' - tongues) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Cladoxylopsida † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> Lycophytina </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Lycopodiophyta </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Zosterophyllophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Rhyniophyta † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Aglaophyton † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Horneophytopsida † </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Bryophyta (mosses) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Anthocerotophyta (hornworts) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Marchantiophyta (liverworts) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Charophyta </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> Chlorophyta </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <Table> <Tr> <Td> </Td> <Td> <P> Trebouxiophyceae (Pleurastrophyceae) </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Chlorophyceae </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> <Tr> <Td> </Td> <Td> <P> Ulvophyceae </P> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table> </Td> </Tr> <Tr> <Td> </Td> </Tr> </Table>

Why does the plant need to grow around a support