HOW TO KNOW THE FRESH-WATER ALGAE 



303b Cells short-cylindric or quadrate; overlapping of wall sections not 

 apparent but visible at the end of broken filaments; lateral mar- 

 gins of cells strictly parallel. Fig. 213 BUMILLERIA 



Fig. 213. Bumilleria sicu- 



gv ' -v 



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v.lfttSi ■■•■ 



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Figure 21 3 



_ There are 2 species 

 known from the country, 

 B. exilis' Klebs being much 

 smaller (6 jj. in diameter) 

 than the one figured. The unbranched filaments are similar to Tri- 

 bonema (Fig. 212) but the cells are more nearly rectangular in optical 

 section, with parallel lateral walls. Sometimes external overlapping 

 H-shaped sections of thicker wall layers, brownish in color, occur inter- 

 mittently along the filament. 



304a (300) Plant a small (1-2 mm. diam.) green vesicle, balloon-shaped; 

 terrestrial. Fig. 214 BOTRYDIUM 



Fig. 214. Botrydium granulation (L.) 

 Grev. 



On damp soil under green house 

 benches or on mud of lakes where water 

 has receded tiny green, balloon-like 

 growths appear. These are siphonace- 

 ous members of the Chrysophyta which 

 have underground rhizoidal branches 

 in which resting spores may be found. 

 Plants can be seen with the unaided 

 eye or are easily detected with a hand 

 lens. Although dark green in color the 

 plant has other characters which relate it to the yellow-green algae, 

 such as the absence of starch and the possession of zoospores with 

 flagella of unequal length. There is another species, B. Wallrothii Kuetz., 

 which has a thick, wrinkled, lamellate wall. 



304b Plant not a green vesicle; aquatic 305 



305a Cells solitary or incidentally clustered 306 



305b Cells in colonies, definite or indefinite in shape and arrange- 

 ment; sometimes forming stalked colonies 333 



306a Cells attached, sessile, or on a stalk 307 



306b Cells free-floating or swimming 314 



307a Cells sessile 308 



307b Cells on a short or long stalk 310 



Figure 214 



132 



