One of them, Bunter Feldblumenstrauss (Colourful Meadow Flowers), a 21 x 18in (55 x 46 cm) oil on canvas from 1886, is in the July 18 auction at Ketterer in Munich.
The catalogue estimate is €30,000-40,000.
Dietrich was born in the eastern German town of Wittenberg and was taught the art of painting by her father. She soon developed her style of meticulously accurate depictions of flowers, which were appreciated not only in Germany.
Judging by the fact that between 1866 and the 1890s she was represented at exhibitions in Brooklyn and San Francisco, it is assumed that she spent a considerable time in the US. Although her date of death is recorded, little else is known about her life. The paintings she left behind must speak for themselves.