316 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



tation to the terrestrial habit of the genus is found in the fact 

 that the ripe sporangia frequently are cast off from the frond 

 entire, and emit the zoospores only when they fall into water, or 

 are wet with dew or rain. The terrestrial habit makes the 

 species of Trentepohlia very accessible to lichen-forming fungi, 

 and in many cases it is rather an exception to find a plant not 

 at all lichenized. 



KEY TO THE SPECIES OF TRENTEPOHLIA. 



i. Cells cylindrical. 2. 



i. Cells roundish, ellipsoid or fusiform. 7. 



2. Sporangia scattered or in series. 3. 



2. Sporangia in a glomerule or raceme. 6. 



3. Filaments subsimple, tapering, acute. 4. T. effiisa. 



3. Filaments branching, not tapering nor acute. 4. 



4. Filaments 4-10 /j. diam. 3. T. abictina. 



4. Filaments 10-32 A diatu. 5. 



5. Filaments usually 12-20 M, sometimes a little more or less. 



i. T. aiirea. 

 5. Filaments 28-32 M. 2. T. villosa. 



6. Glornerule terminal. 5. T. arboruni. 



6. Raceme short, lateral. 6. T. Wainoi, 



7. Filaments 6-12 /u. 7. T. lagenifera. 



7. Filaments 12-44 /*. 8. 



8. Growing on rocks, rarely on mosses. 8. T. lolitfius. 



8. Growing on bark of trees. 9. T. odorata. 



8. Growing on lichens. 10. T.rigidnla. 



i. T. AUREA (L.) Martius, 1817, p. 351 ; Hariot, 1889-90, 

 p. 7 ; P. B.-A., Nos. 569, uSS, 1376 ; Chroolcpns anrcnm Wolle, 

 1887, p. 121, PI. CXV, figs. 1-21. Color golden to orange, 

 yellowish when dry ; basal filaments cylindrical or more or less 

 torulose, erect filaments cylindrical or sometimes slightly con- 

 stricted at the nodes, parallel or irregular, more or less branched, 

 usually obtuse ; forming dense tufts or extended strata ; branches 

 somewhat tapering; cells usually 12-20 ^ diam., but with ex- 

 treme forms 8-30 ^ ; membrane either smooth or roughened 

 with minute scales ; gametangia 20-38 /* diam., globose or ellip- 

 soid, terminal or lateral, borne directly on the vegetative cells ; 

 sporangia similar, on the special curved cells. 



An extremely variable species, inhabiting all parts of the 

 world ; characterized by the C} T lindrical, not mucronate filaments 

 of moderate diameter, and by the solitary or seriate gametangia. 

 In the typical form the membrane is usually smooth, and the 

 gametangia scattered ; T. nncinata (Gobi) Hariot is a synonym. 



