From New Braunfels Herald-Zeitung on June 14, 2022:
John O. Siemssen passed away peacefully at home surrounded by his immediate family on March 23, 2022 at the age of 76 after a long courageous battle with a disabling illness. He was the son of German immigrants, Johannes Christian Siemssen and Kaethe Hildebrandt and was born in Manhattan and raised in Queens, N.Y.
After graduating from Stuyvesant High School, a magnet public college-preparatory high school in New York City, John completed an undergraduate degree in Chemical Engineering at Columbia University, followed by a Master’s degree in the same field from the University of Florida, where he met his future wife, Janet. Later he earned a Master’s degree in Finance from the University of Houston. His long career included research in non-polluting oil refining processes with Sinclair Oil in Chicago, Illinois, international and other business ventures with Atlantic Richfield in Los Angeles, California, and was a plant manager for polymer products with Lyondell-Bassell Petro-Chemical Industries in Houston, Texas.
John was an honest and unassuming man. He was optimistic, kind, generous and always willing to share his knowledge. His interests were numerous and varied. He was a runner of many decades and ran in the Chicago marathon. But he was most passionate about gardening, nature, Texas history, his German heritage and loved preparing creative meals for his family. After retiring to the New Braunfels area, he avidly pursued his many interests. He was especially active in the Lindheimer Chapter of the Native Plant Society of Texas for which he was a past president and author of numerous articles. His other volunteer efforts included such organizations as Texas Master Naturalists and the German Texan Heritage Society in Austin. He was in high demand as a public speaker for various groups and organizations on Texas nature, native plants and wild life habitats. He loved to travel to his family’s homeland of Germany and surrounding countries to visit cousins. But his favorite destinations were in Texas, especially West Texas and the Big Bend National Park area where he loved exploring and photographing the diverse species of desert plants.
He was the cherished husband of his surviving wife, Janet of 53 years; the beloved father of John Anthony, and Karen Jean; and the proud Opa of two beautiful grandchildren, Seona and Seohee. He is also survived by daughter-in law, Teresa, brothers-in-law, Roy and Ray Hamlin, nieces and nephews in Florida, and his German cousins.