HOW TO KNOW THE SEAWEEDS 



159b Tetrasporangia developing from the innermost cortical cells. Fig. 

 203 Rhodoglossum (in part) 



Fig. 203. Rhodoglossum sp. 



Part of a transection of a tetrasporic 

 blade to show the origin of the tetraspor- 

 angia (undivided) from the inner corti- 

 cal cells (redrawn from Kylin). 



Several species of Rhodoglossum oc- 

 cur along the Pacific coast which are 

 similar in habit to species of Iridophycus 

 (See Fig. 202). These unbranched forms 

 with entire blades will be somewhat dif- 

 Figure 203 ficult for the Student to recognize until 



some experience is gained with them. 

 There are only four species, however, all confined to California except 

 one from Puget Sound. They usually will be less abundant than the 

 species of Iridophycus, and, apart from the tetrasporangial character 

 pointed out above, they may be distinguished in another way. Iridophy- 

 cus plants after drying will ordinarily disintegrate when soaked up in 

 fresh water, while specimens of Rhodoglossum will not respond in this 

 way. 



Note that our commonest species of Rhodoglossum, R. affine, is 

 dichotomously branched and appears at step 170b in the key. 



160a Erect blades pectinately branched from a creeping stolon with 

 sand-penetrating rhizoids. Fig. 204 Caulerpa crassifoUa 



Fig. 204. Caulerpa crassifoUa (C. 

 Agardh) J. Agardh 



A portion of a plant to show the 

 erect, pectinate, flattened blades and 

 sand-penetrating rhizoids from the 

 creeping stolon, X 0.7. This common 

 species of Florida keys out apart from 

 other species of the genus because of 

 the flattened character of the branched, 

 erect parts. Other species will be noted 

 under steps 59a and 148a. 



'XTC^ 



Figure 204 



154 



