154 



SUBKINGDOM ALGAE: 



Reproduction: chiefly sexual in a complex diplobi- 

 ontic life cycle in two of the three classes; the remain- 

 ing class has little or no indication of a gametophyte, 

 the life cycle being essentially haplobiontic, adult 

 diploid; diplobiontic cycles are characterized by like 

 or unlike gametophytes and sporophytes; some cycles 

 are obligate (the sporophyte must give rise to the 

 gametophyte directly and vice versa), but others are 

 not obligate; nonobligate cycles involve the sporo- 

 phyte giving rise to neutral spores which develop into 

 another sporophyte, and many sporophyte genera- 

 tions occur before gametophytes are produced; each 

 sporophyte generation usually has a spore-producing 

 sporangium; nonobligate cycles often also feature one 

 gametophyte generation giving rise to another from 

 unfertilized eggs; therefore, the cycle may involve a 

 block of gametophyte generations followed by a block 

 of sporophyte generations; nonobligate cycles regu- 

 larly show seasonal associations (sporophyte blocks 

 being produced in the winter), but they may not. 



Occurrence: almost strictly marine, mostly cold 

 waters and attached to a nonliving substrate; 3 rare 

 fresh-water species are known; about 1500 species. 



RHODOPHYTA (Red Algae) 



Structure: cellular organization, rarely unicellular 

 or colonial; commonly red plants, but also greenish, 

 olive to dark brown, purple, or blackish (regularly 

 turn reddish after a few minutes' boiling in alcohol); 

 multicellular species often are filamentous (simple or 

 branched) and often more complex with holdfast, 

 stipe, and blades as in some Phaeophyta and Chlo- 

 rophyta; complex species also are thin and mem- 

 branous, solid, branched, or irregular sheets; also 

 some are simple or branched, solid cylinders or tubes 

 which are sometimes small and feather- or fern-like, 

 sometimes cylinders or tubes are within narrow, flat 

 sheets; some forms are covered with calcium carbon- 

 ate and are encrusted or coarse to feathery branched 

 (Figure 9.4). 



Cells: nuclei complete and complex, one or more 

 per cell; plastids with a unique chlorophyll; some pig- 

 ments are similar to those of the Cyanophyta and 

 some green flagellates; most have a large, central 

 vacuole; cell wall of two layers (outer gelatinous and 

 inner mostly cellulose) but cytoplasm is continuous 

 via cell wall pores in some species, other species hav- 

 ing the pores covered by the cell membrane; without 

 flagellated cells of any kind. 



Nulnlum: probably strictly photosynthetic. 



most green and brown algae growth is 

 duplicated and some resemble stoneworts 



coral kelp^ 



encrusted 



Figure 9.4 A unique red algae type, the calcium carbonate en- 

 crusted coral kelp, CoraUma. Red algae growth forms duplicate 

 those shown tor both green and brown algae. 



Reproduction: asexual rare, mostly by one or more 

 kinds of nonmotile spores, but occasionally by frag- 

 mentation (usually kills plant parts); commonly sexual 

 with complex diplobiontic life cycles. 



Occurrence: mostly marine and attached to the 

 substrate, widespread (but not common in coldest 

 waters) and occur in waters deeper than any other 

 algae; about 200 fresh-water forms; about 3500 

 species. 



SELECTED READINGS 



Dawson, E. Y., 1956. How to Know the Seaweeds. Wm. C. 

 Brown Co., Dubuque, Iowa. 



Guberlet, M. L., 1956. Seaweeds at Ebb Tide. University of 

 Washington Press, Seattle, Wash. 



Prescott, G. W., 1954. How to Know the Fresh-Water Algae. 

 Wm. C. Brown Co., Dubuque, Iowa. 



Smith, G. M., 1950. The Fresh-water .Mgae of the I'mled 

 States. 2nded. McGraw-Hill Book Co., New York. 



. 1954. Marine Algae of the Monterey Peninsula. Stan- 

 ford University Press, Stanford, Calif. 



. 1955. Cryptogamic Botany. Vol.1: Algae and Fungi. 



McGraw-Hill Book Co., New York. 



