George Engelmann, also known as Georg Engelmann, (2 February 1809 – 4 February 1884) was a German-American botanist. He was instrumental in describing the flora of the west of North America, then very poorly known to Europeans; he was particularly active in the Rocky Mountains and northern Mexico, one of his constant companions being another German-American, the botanical illustrator Paulus Roetter.

George Engelmann was born in Frankfurt am Main, Germany, the oldest of thirteen children, nine of whom reached maturity. His father, Julius Bernhardt Engelmann, was a member of a family from which for several successive generations were chosen ministers for the Reformed Church at Bacharach-on-the-Rhine. Julius was a graduate of the University of Halle, and was also educated for the ministry, but he devoted his life to education. He established a school for young women in Frankfurt, which was rare at the time. George Engelmann's mother, Julie Antoinette, was the only daughter of Antoinette André and George Oswald May. The latter, in his earlier years, was an artist of note at the Court of Weimar. Julie Antoinette was Julius Engelmann's coadjutor in the school for young women, and its success was largely due to her management and tact.

His cousin, Adolph Engelmann, was a colonel during the Mexican-American War and the American Civil War.

George Engelmann received his early education at the gymnasium in Frankfurt. According to himself, he first became interested in plants around age 15. He voluntarily devoted much of his time after school duties to studying history, modern languages, and drawing.

Assisted by a scholarship (founded by the “Reformed Congregation of Frankfurt”), in 1827 he began to study sciences at the University of Heidelberg, where he met Karl Schimper and Alexander Braun. With the latter especially an intimate friendship and correspondence were preserved unbroken until Braun's death in 1877. He also retained friendship with Schimper. However, that erratic genius abandoned botany despite obtaining a remarkable grasp of philosophical botany and laying the foundations of phyllotaxy.

In 1828 young Engelmann's studies at Heidelberg were interrupted by his having joined the students in a political demonstration. He thereupon left Heidelberg and entered the University of Berlin, where he stayed for two years. In 1831, he received the degree of MD from the University of Würzburg.

His dissertation for the medical degree, more related to botany than to medicine, was published at Frankfurt in 1832 under the title of De Antholysi Prodromus. It was devoted to morphology — mainly to the structure of monstrosities and aberrant forms of plants — and was illustrated by five plates of figures drawn and transferred to the lithographic stone by the author's own hand. Its subject was so directly in line with that of a treatise on the metamorphosis of plants by Johann Wolfgang von Goethe that it was heartily welcomed by the poet-philosopher, whose own life was then approaching its close. Having received Engelmann's treatise through his correspondent Marianne von Willemer, Goethe inquired after the young author, saying that Engelmann had completely apprehended Goethe's ideas concerning vegetable morphology, and had shown a peculiar genius for their development. So strong was his confidence in Engelmann's ability that he offered to give him his whole store of unpublished notes and sketches.

In 1832 Engelmann went to Paris, where he again became associated with Braun, and also with Louis Agassiz.