Malus sieversii modern apple cultivars. Unlike domesticated varieties its leaves go red in autumn: 62.2% of the trees in the wild do this compared to only 2.8% of the regular apple plant or the 2,170 English cultivated varieties. The species is now considered vulnerable to extinction. "Malus sieversii" has previously been identified as the main contributor to the genome of the cultivated apple ("Malus pumila"), on the basis of morphological, molecular, and historical evidence. A DNA analysis in 2010 confirmed "M. sieversii" as the progenitor of the cultivated apple. A third species that has been thought to have made contributions to the
Étienne-Louis Malus Étienne-Louis Malus Étienne-Louis Malus (; ; 23 July 1775 – 24 February 1812) was a French officer, engineer, physicist, and mathematician. Malus was born in Paris, France. He participated in Napoleon's expedition into Egypt (1798 to 1801) and was a member of the mathematics section of the Institut d'Égypte. Malus became a member of the Académie des Sciences in 1810. In 1810 the Royal Society of London awarded him the Rumford Medal. His mathematical work was almost entirely concerned with the study of light. He studied geometric systems called "ray systems", closely connected to Julius Plücker's "line geometry". He conducted