PAPENFUSS: CLASSIFICATION OF THE ALGAE 129 



Order CLADOPHORALES West (1904, p. 56) 



Family Cladophoraceae (Hassell) Cohn (1880, p. 289) 



Syn.: Pithophoraceae Wittrock (1877, p. 47) 

 Family Arnoldiellaceae Fritsch (1935, p. 246) 

 Family Anadyomenaceae Kiitziug orth. mut. Hauck (1884, p. 420) 



Syn.: Microdictyaceae (De Toni) Setchell (1929, p. 584) 

 Order SIPHONOCLADALES (Blackmail et Tansley) Oltmanns (1904, p. 134) 



Syn.: Valoniales Pascher (1931, p. 327), vonien nudum 

 Family Valoniaceae Nageli (1847, p. 154) 

 Family Siplionocladaceae Schmitz (1879a, p. 20) 



Syn.: Apjohniaceae Setchell (1929, p. 584), nomen nudum 

 Family Boodleaceae (Bdrgesen) Brirgesen (1925, p. 19) 

 Order SIPHONALES Wille, in Warming (1884) orth. mut. Blackman et Tansley 

 (1902, p. 114) 



Syn.: Codiales Setchell (1929, p. 584); Caulerpales Setchell (1929, 



p. 584); Pascher (1931, p. 327); Feldmann (1946, p. 753), nomen 



nudum; Eusiphonales Feldmann (1946, p. 753) 

 Family Derbesiaceae (Thuret) Kjellman (1883, p. 316) 



Syn.: Halicystidaceae G. M. Smith (1930, p. 227; see also 1944, p. 69) 

 Family Dichotomosiphonaceae Chadefaud ex Feldmann (1946, p. 753) 

 Family Caulerpaceae Greville ex Kiitzing orth. mut. Cohn (1880, p. 288) 

 Family Bryopsidaceae Bory orth. mut. De Toni (1888, p. 449) 

 Family Codiaceae (Trevisan) Zanardini (1843, table opposite p. 171) 



Syn.: Udoteaceae (Endlicher) J. Agardh (1887-1888, p. 12; see also 



Feldmann, 1946, p. 752) ; Siphonaceae Greville orth. mut. Harvey 



(1849, p. 190); Spongodiaceae Lamouroux orth. mut. De Toni (1888, 



p. 449) 

 Order DASYCLADALES Pascher (1931, p. 328, fn. 37) 



Family Dasycladaceae Kiitzing orth. mut. Stizenberger (1860, p. 32) 



Syn.: Acetabulariaceae (Endlicher) Hauck (1884, p. 421) 



Phylum Chakophycophyta 



Characterization: Members of this isolated group of only seven living genera have 

 erect, whorled, equisetoid, haploid, branched thalli that grow by means of a conspicuous 

 dome-shaped apical cell and are attached by multicellular, branched rhizoids. By trans- 

 verse division, the apical cell cuts off segments proximally. Each segment divides trans- 

 versely into an upper nodal and a lower internodal cell. The internodal cell elongates 

 greatly but undergoes no further septation. The nodal cell divides by vertical and curved 

 walls to form a nodal tissue, certain peripheral cells of which become apical cells and 

 give rise to a whorl of laterals of limited growth, the "leaves." The "leaves" are likewise 

 differentiated into nodes and internodes and may be simple or branched. Indeterminate 

 branches when formed, are produced in the axils of the laterals of limited growth. 



The internodal cells of the axes and of the short laterals may or may not be ensheathed 

 by a layer of cortical filaments that are produced by the basal nodes of the whorl of short 

 branches. Some grow upward and ensheath the basal half of the internodal cell next 

 above, others grow downward and cover the upper half of the internodal cell below. The 

 cortical filaments grow by means of an apical cell and are also differentiated into nodal 

 and internodal cells. 



Young and small cells are uninucleate, whereas the large internodal cells become 

 multinucleate by amitosis. The cells contain many small discoid chloroplasts which lack 

 pyrenoids. As far as known, the pigment complex does not differ from that of other green 

 plants, and food is stored as starch. The wall consists of an inner cellulosic and an outer 

 gelatinous layer of unknown composition. In many species the thallus becomes calcified. 



Vegetative multiplication is of common occurrence. Secondary protonemata may 

 develop from the primary rhizoid or the primary protonema or the nodes of plants that 



