Phylum Phaeophyta [91 



perfectly analogous to the sieve tubes of higher plants; the nuclei remain alive. The 

 minute zoospores are produced in unilocular sporangia. These occur on the surface 

 of the body in dense masses, intermingled with, and protected while young by, spe- 

 cialized sterile hairs. 



Individuals of Laminaria consist simply of hapteres, a stalk, and one or more 

 terminal blades. In various other genera, growth occurs in such fashion as to cause 

 the blades to split at the base. With further growth, the splits extend to the margins 

 of the blades and increase their number, while intercalary growth at the transitions 

 between the stalks and the blades produces elongation and branching of the stalks. 

 Early explorers described the stalks of Macrocystis pyrifera as reaching prodigious 

 lengths, matters of hundreds of meters, and these accounts have been repeated in 

 textbooks down to recent times. Frye, Rigg, and Crandall (1915) found a maximum 

 length of somewhat less than fifty meters. The stalks are dichotomously branched 

 to a moderate extent and bear series of blades, each with a pear-shaped pneumato- 

 cyst or float at the base. The stalks of Nereocystis Luetkeana also were said to be 

 extremely long, but the recent observers did not find them to attain fifty meters. They 

 are unbranched and bear a single large float from which spring several blades which 

 may exceed four meters in length. This great organism is an annual, growing and 

 dying within a year. Postelsia palmaeformis, called the sea palm, grows on rocks ex- 

 posed to surf. It has erect stalks some 30 cm. tall bearing many pendant linear blades. 

 Egregia Menziesii has flattened stalks many meters long with fringes of floats and 

 blades along the margins. Laminaria is widely distributed. Macrocystis occurs on the 

 northwest coast of North America and in southern oceans. The other kelps which 

 have bef:n mentioned are confined to the northwest coast of North America. 



On coasts where they occur, kelps are used as fertilizer. They have been used com- 

 mercially as sources of potash, as much as 1-3% of the fresh weight being K as K2O 

 (Cameron, 1915); they have been used also as sources of iodine. These uses are not 

 economic at most times. 



Setchell and Gardner divided the proper kelps, of which there are about one 

 hundred species, into four families. The groups of less elaborate structure which ap- 

 pear properly to be placed in the same order are treated by Papenfuss (under Dictyo- 

 siphonales) as six families. 



Order 7. Fucoidea [Fucoideae] C. Agardh Syst. Alg. xxxv (1824). 

 FucoiDEAE C. Agardh Synops. Alg. Scand. ix (1817). 

 Tribe Angiospermeae Kiitzing Phyc. Gen. 349 (1843). 

 Order Cyclosporeae Areschoug in Act. Roy. Soc. Upsala 13: 248 (1847). 

 Order Fucaceae J. Agardh Sp. Alg. 1 : 180 ( 1848). 

 Order Sargassaceae Haeckel Gen. Morph. 2: xxxv (1866). 

 Order Fucales Bessey in Univ. Nebraska Studies 7: 290 (1907). 

 Order Cyclosporales and suborder Fucineae Taylor in Bot. Gaz. 74: 439 (1922). 

 Class Cyclosporeae Kylin in Kungl. Fysiog. Sallsk. Handl. n. f. 44, no. 7: 91 

 (1933). 

 Thallose brown algae, producing no spores, diploid in all stages except the gametes; 

 the latter being sperms, whose posterior flagellum is longer than the anterior one, 

 and non-motile eggs. The genus Fucus L. is to be construed as the type genus of order 

 Fucoidea, class Melanophycea, and phylum Phaeophyta. 



Two families are usually recognized (others have been segregated). In family 

 Fucea [Fuceae] Kiitzing (family Fucaceae Cohn), called the rockweeds, the bodies 



