Johan Martin Christian Lange (20 March 1818 – 3 April 1898) was a prominent Danish botanist.

He was Director of the Botanical Garden there from 1856 to 1876, the Reader of botany at the Danish Technical University from 1857 to 1862, and Reader of Botany at the Royal Veterinary and Agricultural University from 1858 to 1893, achieving full professor standing in 1892.

Together with Japetus Steenstrup, Johan Lange was the publisher of Flora Danica fasc.

[2] He travelled throughout Europe, completing extensive studies on the flora of Denmark, Greenland and other European countries, especially Spain.

[1] He is honoured in the naming of a fungal genus in 1891, Willkommlangea (jointly with Heinrich Moritz Willkomm (1821-1895), who was a German academic and botanist).