99 



Synoptical Key 



to the species of Amphiroa. 



I 

 I. Fronds thick, cylindrical or flattened but with round edges; ramification dichotomous or 



irregular; adventitious branches springing from the joint never from the node. Node consisting 



only of the central strand; cortical layer of calcified tissue splitting horizontally around the 



non-calcified node or not splitting at all. In this case node outwardly only visible as a narrow 



constriction of the frond. Conceptacles at first a little prominent afterwards entirely immersed: 



1. Amphiroa crassa Lamx. 

 f. Godeffroyi Grun. 



f. minitta n. f. 



2. Amphiroa tribulus Lamx. 



II. Fronds flattened, cylindrical, thick with distinct nodes in the structure of which central strand 

 and cortical layer take part. Nodes sometimes larger at the under side than at the upper 

 sicle in A. canaliculata ; cortical calcified layer of upper joint overlaps in older joints the 

 node and touches the lower joint : 



fronds canaliculate. 3. A. canaliculata v. Mart. 

 fronds not canaliculate. 4. A. involuta Kütz. (syn. A. capensis Aresch.). 



III. Fronds cylindrical or flattened with sharp thin edges ; ramification dichotomous. 



a. Nodes usually in pairs consisting of part of central strand and part of cortical layer and 

 appearing at first as two little cylinders at base of joint; when fully developed three small 

 teeth of calcareous tissue, one in the middle and one at each side of the node, are visible : 



5. A. anceps (Lamk.) Dec. 



b. Nodes like those of A. anceps but also with little dots of calcareous tissue on the nodes: 



6. A. Bowerbankii Harv. 



c. Node composed of entire central strand and almost entire cortical layer; with only 

 two little teeth of calcareous tissue one at each side of the usual single node : 



7. A. Beauvoisii (Lamx.) Born. 

 IA. zona fa Yendo. 



}A. echigoensis Yendo. 

 ? A. pit si l la Yendo. 



d. Node consisting of entire central strand and entire cortical layer. No little teeth of 

 calcareous tissue at base of node : 



8. A. ephcdraca (Lamk.) Aresch. 

 f9. A . lincaris Kütz. 



IV. Fronds cylindrical, joints swollen padlike at top and base or not swollen in a young state 

 and never in A. anastomosans ■; rows of cells in central strand almost horizontal not 

 curved. Nodes consisting of entire central strand and cortical layer, swollen cushionlike 

 to bear the joints or not swollen in a young state, and obsolete never swollen in A. 

 anastomosans. Conceptacles very prominent: 



