green plants have trans-neoxanthin. The authors interpreted this result as an indication of the early divergence of Mesostigma , prior to the evolution of the cis-isomerases necessary to convert trans to cis (in all other green plants). In contrast, Martin et al. (2002) ? analyzed 274 protein-coding genes in analysis of 16 plastid genomes, including Mesostigma , two other noncharophyte green algae, and six embryophytes, and found a topology congruent with nesting of Mesostigma within the charophyte algae-embryophyte clade as in Karol et al. (2001) ? . Clearly, genomic sampling is just beginning and should clarify these positions. Chlorokybales This order is monotypic, with thalli of sarcinoid packets of cells that grow subaerially (Rogers et al., 1980 ? ). Biflagellate scaly zoospores are produced, with hairy flagella that possess an MLS in the root. The four-gene analysis of Karol et al. (2001) ? and Delwiche et al. (2002) ? placed this species in the charophyte algae, near the base of the lineage. Klebsormidiales These algae are simple unbranched filaments with parietal laminate or lobed chloroplasts. Zoospores have an MLS-type root and two asymmetrical flagella. Klebsormidium was proposed by Silva et al. (1972) ? to remove confusion attending the name Hormidium when the alga was considered a member of Chlorophyceae. Klebsormidium contains approximately 24 species, and Lokhorst (1996) ? monographed European taxa. Two genera ( Stichococcus and Raphidonema ) thought to be members of the order are not, but Entransia fimbriata , originally placed by Hughes (1948) ? in Zygnematales, is