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THE SEAWEEDS 
Order RHODYMENIALES Oltmanns 1904. 
Plants showing various shapes from filiform to fleshy-membranous, some- 
times hollow; corticated, with a modified multiaxial type of structure; 
asexual reproduction by tetraspores formed after meiosis in sporangia scat- 
tered over the plant just below the surface; sexual reproduction by sperma- 
tangia borne on surface cells in more or less restricted areas and by carpo- 
gonidia on carpogenic branches sunken in the cortex ; typical auxiliary cells 
present, established before fertilization by segmentation indirectly from the 
cell supporting the carpogenic branch; gonimoblast filaments developed 
from the auxiliary to form carpospores enveloped by a pericarp. 
Family RHODYMENIACEAE Schmitz 1889. 
Plants plane or bushy, nearly simple or somewhat freely divided, the 
divisions flat and subdichotomous or subcylindrical and radially branched, 
solid or hollow, soft to tough-membranous; developing from an apical 
meristem, the innermost cells large, forming a parenchymatous medulla, the 
surface cells small, often in short radial series and containing the chromato- 
phores; sporangia sometimes in sori, tetrapartite, formed between these 
superficial cells from the ends of shortened radial filaments; carpogenic 
branch three celled, the supporting cell also cutting off an auxiliary mother 
cell; gonimoblasts extensively branched, most of the cells forming rather 
small carpospores, the whole eventually enveloped by a loose pericarp, but 
no sterile filaments penetrate the carpospore mass. 
Hymenocladia J. Agardh. Bhodymenia Greville. Chrysymenia J. 
Agardh. Bindera Harvey. Epymenia Kiitzing. Gloioderma J. Agardh. 
Gloiosaccion Harvey. 
Family CHAMPIACEAE Eliding' 1928. 
Plant usually bushy, sometimes sparingly branched, branches cylindrical 
or compressed, delicately membranous to quite soft; from an apical meri- 
stem developing superficial small assimilatory cells, an inner cortex of 
large cells and a medullary cavity traversed by longitudinal filaments, the 
filaments bearing lateral secretory cells ; tetrahedral sporangia formed from 
cortical cells and lying just below the surface; spermatangia borne on 
groups of surface cells of the small male plants, carpogenic branches three- 
or four-celled, each borne on an inner cortical cell the Auxiliary secondarilv 
derived from the supporting cell ; after fertilization the carpogenic branch, 
auxiliary cell, and others join into a large fusion cell, from which the 
gonimoblasts and in turn the large carpospores are formed, the whole 
covered by a prominent ostiolate pericarp. 
Champia Desvaux. Chylocladia Greville. Erythrocolon J. Agardh. 
