DECEMBER 1968 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 11(3): 277-392 



Key to the Genera (Part III) 



1. Vegetative plant without leaves; consisting of a thallus or of flagelliform stolons, or of 

 branched filaments; male and female inflorescence foliaceous, the bracts with a lamina. 

 2. Plants branched, filamentous. 



3. Axis few-celled, branched; 1- or 2-celled leaves evident. 



Regredicaulis monodactylus. p. 359 

 (forms of) Arachniopsis. p. 361 

 3. Axis absent; filaments uniseriate, irregularly branched, alga-like. 



Protocephalozia. p. 333 



2. Plants thalloid or of branched, flagelliform leafless stolons. 



3. Thallus with a well defined mid-rib and unistratose wings; wing margins with 



scattered, very long "slime" papillae parallel to the margin. Pteropsiella. p. 372 



3. Stolon-like branched flagelliform axes tiny, leafless; rhizoids scattered, not in tufts. 



Phycolepidozia. p. 383 



1. Vegetative plant leafy. 



2. Leaves without a lamina, consisting of 1 or a pair of short or long uniseriate seg- 

 ments; underleaves of 2 adjacent cells, often bearing rhizoids. 

 3. Segments 1 or 2 cells long; cells more or less spherical or short ovoid. 



Regredicaidis monodactylus. p. 359 

 3. Segments 4 or more cells long; cells long rectangular in outline with the tip cell 



short. Arachniopsis. p. 361 



2. Leaves with a lamina of few to many cells. 



3. Leaves incubous, the insertion oblique to sublongitudinal ; leaf apices rounded, 



mucronate, retuse or shortly bifid. Calypogeia. p. 279 



3. Leaves succubous with the insertion oblique to sublongitudinal, or the leaves 

 subtransverse or transverse. 



4. Leaves with 2 (rarely 1) very long, sausage-shaped "slime" papillae, at the 



tips of the segments or on the rounded margins. Zoopsis. p. 368 



4. Leaves with small, soon disappearing, slime papillae. 



5. Leaves undivided or rarely retuse; underleaves absent or small, scale-like, 

 becoming larger just below a female inflorescence. 

 6. Leaves small, less than 12 cells in width at the middle. 



7. Leaves to twice as long as wide; plants whitish, often becoming red 



near the tips. Alobiellopsis. p. 349 



7. Leaves subquadrate, turgid, yellow-brown; cells with conspicuous 



brown bands of thickening. Trabacellula. p. 352 



6. Leaves larger, 15 to 20 or more cells in width at the middle. 



7. Leaves elongate, subrectangular, the margins crisped or undulate; 

 cells large, with large, translucent, knot-like trigones ; branches 

 dorsilateral and ventral, intercalary; underleaves ovate, with many 

 marginal and superficial slime papillae. Anomoclada. p. 346 



7. Leaves long-oval, subrectangular, or ovate-truncate, never crisped; 

 cells large or small, trigones large to tiny; scale-like underleaves 

 with only occasional slime papillae. Odontoschisma. p. 334 



5. Leaves bifid or at least bidentate (in Alobiella often only slightly so and the 

 leaves appearing acute). 



6. Leaves divided to the middle into 2 similar, broad, rounded segments. 



Cladopodiella. p. 347 

 6. Leaf segments acute or if rounded, the segments conspicuously unequal. 

 7. Underleaves conspicuous, well developed, bifid (an occasional one 

 trifid). 



8. Underleaves and leaves similar in size and form ; cortical layer 

 of the stem of 6 (2 + 24-2) similar, very large, inflated cells. 



Hyalolepidozia. p. 377 



8. Underleaves slightly smaller, or to only half as long as the leaves. 

 9. Leaves long-ovate, bidentate (often appearing acute), the seg- 



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