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

The large, bulbous lip is colored 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 color. The curious visitors fall from the smooth edge of the shoe into its interior. Thus trapped, the insects search for an exit, which is simulated by a translucent area of the lower lip at the rear end of the flower. On their 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 (mycorrhiza) living in the soil, the seed can 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 it among other things as storage organs. If conditions are favorable, 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 the middle of June.

The endangerment of the species is due to the destruction of the habitat. But also its attractiveness has often been the undoing of the lady's slipper. Often the lady's slipper population is threatened due to reckless plundering, 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 blooming season on a voluntary basis and with great commitment.