Corybas papa

Corybas papa is a terrestrial, perennial herb with a solitary fleshy wedge-shaped leaf that is sessile (lacking a noticeable petiole). The tip of the leaf is apiculate, with the minute apex curved downward, and the base is heart-shaped. The leaf is dull green and slightly grooved on the upper surface, with occasionally maroon spotting primarily distributed around the margins, and the undersides are silvery. The tuberoids are roughly spherical. C. papa bears minute solitary green flowers around 10–15 mm long. These flowers are connected to a very short purple-streaked peduncle that greatly elongates as the elliptical capsule (10–16 mm long) ripens. The ovary is curved and is accompanied by two slender floral bracts of unequal length; the shorter one is reduced and points towards the leaf, while the longer, at least double the length of the other bract and around the length of the ovary, points away from the leaf. The flower's dorsal sepal is 15–20 mm in length and forms a slender arching hood over the labellum. It is green and faintly veined with purple. The apex is tapered and extends noticeably beyond the labellum. The lateral sepals and petals are long and filiform (thread-like, only 0.5–mm wide), far exceeding the labellum in length. They are green, sometimes speckled with maroon, and spread radially outward from the flower. …

Corybas papa is endemic to the Taranaki region of New Zealand's North Island. It is known to occur from Port Waikato to the western Ruahine Range. It grows in coastal to montane habitats in calcium-rich papa substrates such as those consisting of mudstone and siltstone (for which it is named). It also grows in basaltic substrates. It usually grows near seepages or on the mossy banks of slow-flowing streams.

C. papa is presumed to be pollinated by fungus gnats. It was observed in lab cultivation that Mycetophila gnats visiting flowers of C. iridescens, a related species in the C. rivularis complex, avoided C. papa, suggesting a reproductive barrier that may have contributed to speciation.