898 AQUATIC PHYCOMYCETES 



short stalk in a compact bunch; these lobes bear the narrow branches 

 which are rather shorter than in the normal form. Rhizoidal system 

 relatively well developed, rhizoids stout with rounded tips. Sporangia 

 as in the species, 50-60 x 25-35 \i. Oogonia pear-shaped, smaller than 

 in the species, 40-45 \x diameter. Oospores smaller than in the species, 

 28-36 \i diameter. Antheridia as in the species" (Forbes, he. cit.). 



Substratum (?), Great Britain. 



This variety is probably based on the peltate form commonly found 

 in both this species and Rhipidium americanum. 



Rhipidium interruptum f. attenuata (Kanouse) Coker 



N. A. Flora, 2 (1): 67. 1937 



Rhipkliiuu europaeum f. attenuata Kanouse, Amer. J. Bot., 14: 342, pi. 48, 

 figs. 27-33. 1927. 



"Vegetative plant very slender, attached by long, slender penetrating 

 rhizoids. Basal portion very long and narrowly subcylindrical, simple 

 or sometimes once forked, 2000-3200 - 20-50 u,, wall relatively thick, 

 7-10 u., protoplasm hyaline, including numerous oil globules upward. 

 Branches scanty, arising from the apex of the main portion, differen- 

 tiated at point of origin by pedicel-like constrictions which are provided 

 with perforated cellulin deposits, very slender and flexible, 200-500 x 

 6-9 (j.. Asexual reproduction typical" (Kanouse, he. eit.). 



On Crataegus and apple fruits, United States. 



Differing chiefly in having a slender, sometimes once-branched, basal 

 cell. 



Rhipidium thaxteri Minden 



Kryptogamenfl. Mark Brandenburg, 5:600. 1912 (1915); Falck, Mykolog. 

 Untersuch. Berichte, 2(2): 188, pi. 3, figs. 22-24. 1916 



(Fig. 71 D, p. 894) 

 Basal cell as in Rhipidium interruptum, often monstrous and discoid, 

 over 800 \x in diameter with lobes up to 200 u. broad, or occasionally 

 more cylindrical, upright filaments constricted only at the base, 7-11 ;x 

 in diameter, free-floating, holdfasts branched; sporangia borne as in the 

 other species or in whorls, narrowly ellipsoidal, 50-89 \i long by 20-38 \l 



