388 University of California Publications in Botany [^''ol. 7 



vegetative portion of iin Ectocarpus of microscopic size. The game- 

 tangia are strict I \- those of a typical Myrionema, but it lacks the disk- 

 shaped basal layer of filaments spreading out on the surface of the 

 host, characteristic of that genus. The extremely reduced character 

 of the penetrating portion does not speak well for the genus Streblo- 

 ncma. On the whole, we feel that with our present criteria for these 

 genera it Ix'st agrees with the characters of the genus Streblonema, 

 M'here we are placing it. It penetrates the uninjured host, but only 

 to a slight depth. The plants, however, are usually so congested that 

 their growth soon crowds the surface layer of the host cells to such an 

 extent that they die and disintegrate, there being no evidence that the 

 associate penetrates them and absorbs their material. Tlic palisade-like 

 stratum of gametangia suggests very strongly the Myrionema character 

 which is the reason for the specific name. 



Streblonema penetrale sp. nov. 



Plate 44, figures 3, 4 



Frondibus stratum continuum pulvijiatumque forma magnitudine- 

 que indefinitum supra stipitem hospitis formantibus ; parte penetrante, 

 filamentis parce ramosis in hospitem comparate profundi penetrantibus 

 et ad superficiem hospitis ]ierpondipularibus composita ; filamentis 

 erectis ad superficiem hospitis fasciculato-ramosis, 70-125/x longis, 

 supra leviter attenuatis, non piliferis; cellulis fllamentorum pene- 

 trantium cylindricis ad irregularibus, 6.5-8ja diam., 3-5-plo longior- 

 ibus; cellulis fllamentorum erectorum cylindricis ad leviter doliiform- 

 ibus, 6.5-8/A diam., 1.5-2.5-plo longioribus; chromatophoris taeniatis; 

 zoosporangiis ignoti.s; gametangiis cylindricis usque ad obtuse-fusi- 

 formibus. plus minusve irregularibus, 30-40/x longis, S-llju, latis ; loculis 

 uniseriatis. 



Growing on the stipes of nesperopliycus Harveyamis. Pacific 

 Grove, California. Type, Gardner, no. 4677 (Herb. Univ. Calif., no. 

 207007), December. 



Streblonema penetrale, like S. my rionemat aides above, is a difficult 

 species to classify. In its method of development and general struc- 

 ture it approximates to 8. myrionematoides closely. The penetrating 

 portion is much more highly developed than in that species, extending 

 into the host among the cells to a depth of four or five times as great 

 as the part which extends beyond the surface. The size of all the parts 

 is, in general, greater than in 8. myrionematoides. No horizontal 

 filaments are present. The penetrating filaments are mostly perpen- 

 dicular to the surface. 



