650 TJniversity of Calif ornia Publications in Botany \yo-i.. 8 



Order 7. DICTYOTALES kjellm. 



Fronds of moderate size, complanate, attached by a more or less 

 extensively stupose base, with the hairs often extending for some dis- 

 tance up the fronds; reproduction both asexual and sexual; the non- 

 sexual spores (aplanospores) usually borne in groups of four, but 

 rarely more, in transformed surface cells projecting singly or in 

 groups beyond the surface; the gametes heterogamous, the female, 

 borne singly in a gametangium, large and non-motile, the male, borne 

 many in a plurilocular gametangium, small and motile by a single ( ?) 

 lateral flagellum ; the male and female gametangia usually in dense 

 sori, and always projecting beyond the surface; hairs numerous, in 

 groups; paraphyses present in some forms. 



Kjellman, in Engler und Prantl., Die natiirl. Pflanzenfam., 1 Teil, 

 2 Abt., 1896, p. 291. 



The order Dictyotales is a distinct, well marked group, but with 

 uncertain affinities. The possession of a brown pigment in addition to 

 chlorophyll is a prominent character of the Melanophyceae. The 

 development of aplanospores in groups of four (tetraspores) is a 

 character common in the Rhodophyceae. The male gamete with but 

 a single cilium is not present elsewhere in either group. The brown 

 pigment and heterogamous method of reproduction seem sufficient to 

 relate them to the Melanophyceae and probably closely to the Fucales, 

 where we are placing the group. It has no zoosporangia or zoospores 

 represented in any of its members. 



FAMILY 23. DICTYOTACEAE harvey (lim. mut.) 



Characters of the order which contains only the single family. 



Marvey, Ner. Bor.-Amer., vol. 1, 1852, p. 99. 



Harvey included all the complex Melanophyceae ''whose spores are 

 superficial and disposed in definite lines or sori. ' ' The Dictyotaceous 

 genera as now understood were included, but also some others such as 

 Punctaria, Soranthera, Stilophora, Dictyosiphon, Asperococcus, and 

 HydroclatJiriis. Harvey, himself, realized that in external habit and 

 even in internal structure, the plants he referred to his order, as he 

 termed it, exhibited "considerable variety." He also stated that "the 

 fructification exhibits considerable diversity of aspect. ' ' 



