Phymatosorus scolopendria, commonly known as monarch fern or wart fern, grows naturally as an epiphyte, lithophyte, or terrestrial plant primarily in the seasonally dry tropical biome, and is widely distributed in Africa, Southeastern Asia, Indonesia, and extending south to northeastern Australia. It has become naturalized in Florida, Bermuda, Hawaii, and localities in South America. Although it is widely distributed geographically, and maintained in cultivation, less is known about its physiological ecology. This is a report of the photosynthesis, respiration, and physiological properties of P. scolopendria grown under controlled laboratory conditions with moderate light intensity of 100 µmol m^–2 s^–1 and temperature of 25C, approximating semi-shaded environmental conditions. Maximum net photosynthesis rate based on leaf area was 1.50 µmol m^–2 s^–1, and based on leaf dry weight was 1,581.80 nmol CO₂ g_dw^–1 min^–1. Dark respiration rate based on leaf area was 0.24 µmol CO₂ m^–2 s^–1, and per leaf dry weight was 319.54 nmol CO₂ g_dw min^–1. The specific leaf area was 209.52. Mean density of stomata on the abaxial leaf surface was 3,242 cm^–2, and leaf stomatal water vapor conductance was c. 62 mmol H₂O m^–2 s^–1.