Knudson C (Anderson, 1990)

Originally cited by Anderson, 1990. Asymbiotic germination of seeds  of some North American orchids. In North American native terrestrial orchid propagation and production, ed. C.E. Sawyers, pp. 75-80. Chadds Ford, Pennsylvania: Brandywine Conservancy.

Ca(NO3)2 * 4 H2O  1000 mg  KH2PO4  228 mg  K2HPO4  7.8 mg  MgSO4 * 7 H2O  125 mg  (NH4)2SO4  250 mg  Ferric ammonium citrate  25 mg  Biotin  0.25 mg  Calcium pantothenate  5 mg  Nicotinic acid  10 mg  Pyridoxine  2 mg  Thiamine  5 mg  Potato extract  50 ml  Glucose  16 g  Agar  6 g

Note: This medium does not employ the use of chelated iron,  resulting in an iron-poor medium. The substitution of ferric ammonium  citrate with EDTA-chelated iron is recommended.

Source: Rasmussen, H. Terrestrial orchids from seed to mycotrophic plant. Cambridge University Press, Cambridge. 1995.