The red alga Laurencia palisada Yamada (Rhodomelaceae, Ceramiales), th
e lectotype species of the section Palisadae, is characterised by the
following set of features: 1) rigidly cartilaginous upright axes arisi
ng from a discoid holdfast; 2) a shift of branching from a distichous
to a spiral manner distally; 3) the production of two periaxial cells
per vegetative axial segment; 4) the absence of longitudinally oriente
d secondary pit-connections between cintiguous superficial cortical ce
lls; 5) the absence of projecting superficial cortical cells; 6) the p
resence of a palisade-like cortical layer; 7) the absence of lenticula
r thickenings in the walls of medullary cells; 8) the absence of corps
en cerise in any cell; 9) the production of two tetrasporangium-beari
ng periaxial cells from each fertile segment; 10) a perpendicular arra
ngement of tetrasporangia; 11) procarps produced from the last-formed
(fourth) peraxial cell of the terminal segment of a two-celled female
trichoblast; 12) flask-shaped cystocarps; and 13) distally positioned
spermatangial nuclei.