690 AQUATIC PHYCOMYCETES 



Blastocladia gracilis Kanouse 



Amer. J. Bot., 14: 300, pi. 33, figs. 14-16. 1927 

 (Fig. 47 A, p. 682) 



Blastocladia ramosa var. luxurious Kanouse, Papers Mich. Acad. Sci., Arts, 

 Letters, 5: 113, pi. 1, fig. 1. 1926. 



Basal cell slender, 20-80 \x in diameter, cylindrical throughout, distally 

 racemosely or subdichotomously branched, walls 2.5-4 \x thick, smooth, 

 contents colorless, setae present or absent, holdfasts few, poorly devel- 

 oped, whole thallus 600-1500 \i long; sporangia racemosely or corym- 

 bosely arranged along the branches, long-cylindrical, 70-220 a long by 

 20-34 [x in diameter, with a prominent discharge papilla; zoospores 

 ovoid 9 by 8 [jl, or subspherical, 8 to 9 (jl, escaping through an apical 

 pore; resting spores borne with the sporangia, usually terminal, ovoid, 

 subspherical or spherical with truncate base, 40-66 jjl long by 20-40 \i 

 in diameter, wall thick, brownish, punctate, upon germination forming 

 zoospores which give rise to new plants. 



In loose tufts or mats with other water molds, particularly Blasto- 

 cladia pringsheimii and Rhipidium. On fruits of apple, Kanouse (loc. 

 cit.), United States; apples, Lund (1934: 43, fig. 20 a-b), Denmark; 

 apples, rose fruits, Crooks (1937: 226, fig. 1 1 A-B), Australia; Water- 

 house (1942: 317, fig. 1, I), Great Britain; tomato fruits, Shen and 

 Siang(1948: 188), China. 



Whether or not this is a form of Blastocladia pringsheimii is open to 

 question. Plants of that species when growing in dense stands in long 

 slits on apple fruits frequently assume the habit of B. gracilis. Water- 

 house (1942) considers the species distinct from B. pringsheimii because 

 the resting spores are more constantly oval and have a more transparent 

 wall and less conspicuous pits. A further distinction is the rapid and 

 prolific development of the resting spores. 



Blastocladia rostrata Minden 



Kryptogamenfl. Mark Brandenburg, 5:604. 1912 (1915); Falck, Mykolog. 

 Untersuch. Berichte, 2: 211, text figs. 18-19, pi. 4, figs. 34-35. 1916 



(Fig. 46 A-B, p. 680) 



Basal cell narrowly or broadly and irregularly cylindrical, 140-150 \x 

 long by 1 5—63 [a. in diameter, profusely branched and rebranched dichot- 



