HOW TO KNOW THE FRESH-WATER ALGAE 



288a Thallus multiaxial (cables of filaments) with closely compacted 

 and oppressed cortical cells; thallus branching irregularly in a 

 dichotomous fashion. Fig. 202 TUOMEYA 



Fig. 202. Tuomeya fluviatilis Harvey, a, 

 habit of thallus; b, apical portion of 

 branch. 



This rather rigid and cartilaginous mem- 

 ber of the Rhodophyta is identified by the 

 complex dichotomous or antler-like habit 

 of branching of the thallus which is com- 

 posed of multiaxial series of filaments and 

 corticating cells. There is but 1 species. 



Figure 202 



288b Thallus including a monaxial filament which is inclosed arffl sur- 

 rounded by compactly arranged and oppressed, polygonal cor- 

 tical cells which form just behind the apex. Fig. 203 



COMPSOPOGON 



Fig. 203. Compsopogon sp., a, habit of 

 thallus; b, portion of axis showing corti- 

 cating cells; c, apical portion of uncor- 

 ticated branch showing chromatophores. 



This is a member of the Rhodophyta 

 which seldom occurs in entirely fresh 

 water but is frequently found in brackish 

 situations, attached to various substrates, 

 but especially to submerged stems of 

 woody plants such as mangrove. C. coe- 

 ruleus (Balb.) Mont, is the most common 

 species. Although essentially filamentous, 

 the thallus is macroscopic in proportions 

 and appears as a rather delicately 

 branched, tufted or bushy growth, blue- 

 or gray- to violet-green in color. It is a tropical and subtropical genus 

 but has been found occasionally in temperate latitudes. 



Figure 203 



126 



