Germination properties, including germination rate, germination percentage and cardinal temperatures, of eight wild medicinal species from Iran were studied. The seeds of the eight medicinal plants were exposed to germination temperature treatments ranging from of 5 to 35 °C consisting of seven constant and three alternating temperature regimes. A linear model was applied to describe the germination rate-temperature relationship. The species studied using constant germination temperatures showed the highest germination percentages in the range of 20–30 °C for Nepeta binaludensis and Nepeta crassifolia, 15–20 °C for Zataria multiflora, 20–25 °C for Nepeta glomerulosa, 25–30 °C for Dysphania botrys and 15–30 °C for Thymus kotschyanus, Rubia tinctorum and Achillea millefolium ssp. elburensis. The highest germination percentage and germination rate were observed at alternating temperatures of 20–30 °C for Nepeta binaludensis, 10–20 °C for Zataria multi- flora, Thymus kotschyanus, Nepeta glomerulosa and Nepeta crassifolia, and, 10–20, 20–30 °C, for Dysphania botrys. The various species showed clear differences in the temperature requirements of their seed for germination. Both germination percentage and rate were higher at constant than alternating temperatures. The highest base (Tb °C) and optimum temperatures (To °C) were observed in Dysphania botrys, while the highest critical temperature (Tc °C) was recorded for Rubia tinctorum. There was a positive linear relation between temperature at which the highest germination percentage was obtained at To, but this relationship was negative for Tb.

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