The taxonomic study of plant in Thailand has been studied for two hundred years ago and it has been mainly focused on flowering plant or economic crops, while pteridophytes have little information. The following are example of previous botanical works.
In 1901, Johannes Schmidt, a Danish botanist, collected plant specimens from Koh Chang, South-eastern Thailand. 67 species and 35 genera of pteridophytes were found (Schmidt, 1901) . In 1922, Eryl Smith, English physician, collected pteridophytes in peninsular Thailand. She collected 1,984 specimens and reported collection of pteridophytes in National History Bulletin of Siam Society. These specimens were kept in Kew Herbarium (K), Natural History (BM), Singapore Herbarium (SING) and Forest Herbarium (BKF). During 1934-1935 Gunnar Seidenfaden reported a small collection of pteridophytes in two different parts of Thailand, Surat circle in Peninsular and Trat circle near Chantaburi, 47 species and 30 genera were recorded. Most of specimens were kept in Natural History Museum of Denmark (C) and Kew Herbarium (K). (Seidenfaden, 1958) 
In 1954, Richard Eric Holttum, Kew botanist, reported 108 genera and 468 species of pteridophytes in “The Ferns of Malaya” (Holttum, 1969) . During 1957-1960, Thailand has been coordinated with Denmark in project “Studies in Flora of Thailand”. Moreover, during 1965-1966 the Center for Southeast Asians studies sent a botanical party to Thailand and the first Thai-Japanese Botanical Expedition was begun in cooperation with Royal Forest Department in Bangkok. Motozi Tagawa and Kunio Iwatsuki, Japanese botanists, studied pteridophyte for Flora of Thailand. In their enumeration, 116 genera and 446 species are listed (Tagawa and Iwatsuki, 1967). In 1979-1989, M. Tagawa and K. Iwatsuki were published 121 genera and 630 species of Pteridophytes in Flora of Thailand Vol. III, part 1-4 (Tagawa and Iwatsuki, 1979, 1985, 1987, 1989)    
- , “Pteridophyta”, in Flora of Koh Chang, Part III, Copenhagen: Bianco Luno, 1901.
- , “On a small Collection of Ferns from Thailand”, Natural History Bulletin of the Siam SocietyNatural History Bulletin of the Siam Society, vol. 19, pp. 84-87, 1958.
- , Flora of Malaya. Vol II. (Ferns). Singapore: Singapore: Government Printing Office, 1969.
- , “Pteridophytes”, in Flora of Thailand, vol. 3, Bangkok: The Tist Press, 1979.
- , “Pteridophytes”, in Flora of Thailand, vol. 3, Bangkok: Phonphan Printing Company, 1985.
- , “Pteridophytes”, in Flora of Thailand, vol. 3, Bangkok: Chutima Press, 1988.
- , “Pteridophytes”, in Flora of Thailand, vol. 3, Bangkok: Phonphan Printing Company, 1989.