Polygala rehmannii is a perennial herb up to 30 cm tall, growing from a woody rootstock. Stems usually hairless, slightly winged. Leaves linear-lanceolate, 10-25 mm long, sometimes much broader near the base, hairless.. Flowers blue or purple-pink and blue.
Polygala rehmannii is very pretty when interplanted with small grasses. It will be equally happy on a rockery. It is very hardy and attract butterflies and bumble bees. The flowers are conspicuous and should be displayed to best advantage.