Pink Lady Slipper (Cypripedium acaule)

Pink Lady Slipper (Cypripedium acaule)

Pink lady slipper flowers, which bloom in early- to mid-June, are a challenge to pollinate due to their unique shape. Only bumblebees and a few other larger species of bee are up for the task of pushing through the narrow opening into the center of the blossom. Unfortunately, pink lady slippers produce pollen, but no nectar. So after repeatedly coming up empty-handed after visiting a few flowers, the bees will learn there is no reward for their efforts and stop visiting other pink lady slipper flowers. As such, many of the blossoms do not get pollinated and therefore do not produce seeds. Because the frequency of pollination is fairly low, it is not uncommon to revisit a place that was bursting with lady slipper flowers in the summer and yet be unable to locate a single seed pod in the winter. 

Finding a seed pod indicates that the plant was successfully pollinated. The woody pod rests at the tip of last year’s 1-foot high stem, and is 1 to 2 inches long. Other identifying features include a long, curled bract at the base of the pod (like the photo above) or remnants of two broad basal leaves at the base of the stalk (like the photo below). Note that because both of these additional features deteriorate faster than the seed pod, they may both be absent: a lack of these features does not mean you have not correctly identified the pink lady slipper’s seed pod. 

Remnant pair of basal leaves

Inside the seed pod are thousands of tiny seeds. Lady slipper seeds, like those of other orchid species, are extremely small, and provide very little energy for the embryonic plant to start its life. In order to germinate, the seeds must be in the right habitat and in the presence of a symbiotic fungus, which will help it absorb and utilize nutrients from the environment.

Thousands of tiny seeds inside the pink lady slipper seed pod

One thought on “Pink Lady Slipper (Cypripedium acaule)

  1. Thank you so much for sharing this! It makes finding a lady slipper that much more amazing especially knowing all its intricacies of germination.

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