Catharina Klein was born in Prussia in 1861. She specialized in painting flowers and fruit and many of her works were used as postcard illustrations. Before the war of 1914 many postcards were produced in Germany. Later she was sometimes known as Catherine and worked in Berlin until her death in 1929. During World War II many of her original paintings were destroyed by bombing by the allies.
Her postcards are quite common, but I’ve not been able to find another postcard online like this one, posted in 1903, of sweet peas.