Practice question

Amborella wood anatomy exhibits exclusively tracheid conducting system lacking vessel elements, retaining torus-less circular bordered pits reminiscent of gymnosperms and pteridophytes, considered primitive. This vessellessness represents plesiomorphic retention not secondary loss, as phylogenetic placement suggests vessels evolved independently after Amborella lineage split within core angiosperms. Nonetheless, Amborella possesses angiospermous phloem with companion cells, enclosed ascidiate carpels and double fertilization yielding triploid endosperm confirming flowering plant affinity despite wood. Carpel, flower, endosperm features present, only vessel elements absent, challenging traditional definition of angiosperms requiring vessels and highlighting mosaic evolution.