292 University of California PuhUcations in Botany [Vol. 8 



half of the thallus is formed into a pseudo-parenchymatous tissue at 

 the time of reproduction, but leaving an abundance of free branching 

 marginal filaments. The thallus of the third is almost wholly trans- 

 formed into a pseudo-parenchymatous tissue at maturity, leaving only 

 a few free marginal filaments. 



27. Endophjrton Gardner 



Filaments sparingly and irregularly branched within the medulla 

 of the host, but branching more freely near the surface, sending off 

 in addition to horizontal branches many short, erect branches perpen- 

 dicular to the frond, the end cells of the perpendicular branches 

 becoming the sporangia and growing out to the surface of the host ; 

 chromatophore band-shaped ; each cell containing a single pyrenoid ; 

 zoospores pyriform, 2-cTliated. 



Endophytic within the fronds of various species of red algae. 



Gardner, New Chlorophyceae, 1909, p. 371 ; West, Algae I, 1916, 

 p. 304. 



This is a form genus, whose cytology is at present too little known. 

 In its habit, it is more thoroughly endophytic than any other genus 

 of the Ghaetophoraceae, since its filaments traverse the medullary as 

 well as the cortical tissues of its hosts. The absence of hairs and 

 specialized zoosporangia seem to mark it as distinct. 



Endophyton ramosum Gardner 

 Plate 11, figs. 3, 4 



Filaments 4-6jU, diam., tortuous, often very irregular in shape ; 

 cells 6-8 times longer than broad, cross-walls distinct ; sporangia club- 

 shaped, tapering to a point at the outer end, when young 10-12/* 

 diam. ; zoospores numerous, 3/* diam., escaping through openings in 

 the upper ends of the sporangia which grow to the surface of the host ; 

 plants occupy small areas a few millimeters in diameter, usually near 

 the base of the frond of the host, but may spread promiscuously over 

 the entire area of the host. 



Endophytic within the fronds of various species of red algae, e.g., 

 Iridaea laminarioidcs, Girjartina exasperata, etc. Central California 

 (San Francisco) and probablj^ farther north. 



Gardner, New Chlorophyceae, 1909, p. 372, pi. 14, f . 3, 4 ; Collins, 

 Green Alg. N. A., 1909, p. 282; Collins, Holden and Setchell, Phyc. 

 Bor.-Amer. (Exsicc), no. 1627. 



