Jones: Flora of Illinois 297 



Xvridaceae 

 Malme, G. O. a., Xyridaceae, N. Am. Fl. 19:3-15. 1937. 



Zy§oph\}llaceae 



Engler, a., Z\igophvllaceae in Engler & Prantl, Die Nat. Pflanzenf. 2 ed. 19a: 

 144.184. 1931. Vail. Anna M., & P. A. Rydberg, Zvgophnllaceae, N. Am. Fl. 

 25:103-116. 1910. 



Pteridophyta 



Benedict, R. C, OsmimJaceae, N. Am. Fl., 16:27-28. 1909.— Broun, M., Index 

 to N. Am. Ferns, 1-217. Orleans. Mass., 1938. — Clausen, R. T., A monograph of 

 the Ophioglossaceae, Mem. Torr. Bol. Club. 19:1-77. 1938. — FerNALD, M. L., Pol\)- 

 podium virginianum and P. vulgare, Rhodora 24:125-142. 1922; American representa- 

 tives of Aspleinum ruta-muraria, loc. cit. 30:37-43. 1928. — Friesner, R. C, Key to 

 genera of ferns and fern-allies, Butler Univ. Studies Bot. 1:55-60. 1929; Key to 

 species and varieties of ferns and fern-allies of n.e. N. Am., loc. cit. 4:142-162. 1940. 

 — Lloyd, F. E., & L. M. Underwood, A review of the species of L\)copodiiim of N. 

 Am., Bull. Torr. Bot. Club 27:147-168. 1900.— Marie-Victorin. Fr., Les Filicinees 

 du Quebec, Revue trimestnelle Canad. suppl. 9:1-98. 1923; Les Lycopodmees du 

 Quebec, Contr. Inst. Bot. Univ. Montreal 3:1-121. 1925. — PiNKERTON, M. ELIZABETH. 

 Ferns and fern allies of Missouri. Ann. Missouri Bot. Card. 20:45-78. 1933. — Pfeiffer, 

 Norma E., Monograph of the Isoetaceae. loc. cit. 9:79-232. 1922. — Schaffner, J. H., 

 N. Am. species of Eqiiiseium, Am. Fern. Journ. 11:65-75. 1921; Diagnostic key 

 to the species of Equiselum, loc. cit. 22:69-75; 122-128. 1932. — SvENSON, H. K., The 

 New World species of Azolla, loc. cit. 34:69-84. 1944. — Tryon, R. M., A 

 revision of the genus Pieridiiim, Rhodora 43:1-31. 1941. — Underwood, L. M. & R. 

 C. Benedict, Ophioglossaceae, N. Am. Fl. 16:1-13. 19C9. Weatherby, C. A., 



A list of vprieties and forms of the ferns of e. N. Am., Am. Fern Jour. 25:45-51, 



95-100. 1935; loc. cit. 26:11-16. 60-69. 94-99. 130-136. 1936; loc. cit. 27:20-24, 51- 

 56. 1937; A new variety of C\)stopkns fragiUs. Rhodora 37:373-378. 1935; The 

 group of Pol\]podiiim pohpodioides, Contr. Gray Herb. 124:22-35. 1939. — Wherry, 

 E. T., Guide to eastern ferns, (ed. 2) 1-252. 1942. — WiLSON. L. R., The spores of 

 the genus Lvicopodiiim in the U. S. and Canada, Rhodora 36:13-19. 1934. 



