The flower of the Yellow lady's slipper (Cypripedium calceolus), a species of orchid up to 70 cm high, which is considered a highly endangered species in Austria and belongs to the protected species of the Flora-Fauna-Habitat Directive of the European Union (= FFH Directive. Aim: conservation and restoration of biological diversity through the establishment of the European network of protected areas Natura 2000).

The large, bulbous lip is coloured yellow, while the twisted petals glow reddish brown in the sunlight. For many insects, the lady's slipper is irresistible. The yellow shoe attracts with its intense colour. The curious visitors fall from the smooth edge of the shoe into its interior. Thus trapped, the insects look for an exit, which is simulated by a translucent spot of the lower lip at the rear end of the flower. On the way out, the insects have to pass very close to the stigma and pollinate the flower.

The lady's slipper forms 40,000 tiny seeds that are spread by the wind. But only through a fungus living in the soil (mycorrhiza) can the seed germinate. However, it takes 7 - 15 years before the plant develops into a flower. A special feature of the lady's slipper are its rhizomes, which serve as storage organs, among other things. If conditions are favourable, the lady's slipper can also reproduce vegetatively (= asexually) via this rhizome and thus form larger clumps.
Semi-shady locations in sparse forests on limestone soil are its habitat. The flowering period begins in mid-May. It lasts until about mid-June.

The endangerment of the species is due to habitat destruction. But its attractiveness has also often been the lady's slipper's undoing. Often the lady's slipper population is threatened due to reckless looting, picking and digging.

The Lady's Slipper area in the Martinauer Au has been looked after for decades by the mountain rescue team during the flowering season on a voluntary basis and with a great deal of commitment.