The giant orchid (Himantoglossum robertianum, syn.: Barlia robertiana), also called Roberts Mastorchis, is a species of plant within the orchid family.
The giant orchid is a perennial herbaceous plant that reaches heights of 25 to 80 centimeters. Two underground oval tubers are formed as survival organs.
There are two to four scale-shaped leaves at the base of the stem. There are only five to ten basal leaves. The simple leaf blade is smooth, shiny and elongated-oval with a length of up to 30 centimeters and a width of about 10 centimeters. The stem is leafless.
The giant orchid generally blooms from late December to spring. One or two narrower leaves surround the flower stalk like a sheath. The racemose inflorescence contains 25 to 60 closely spaced flowers. The lower ones of the bracts are longer than the flowers. The hermaphrodite flower is zygomorphic and tripartite. The three bracts of the outer petal circle are oval and curved forward, the middle one forms a kind of cap with two petals. The lip is three-lobed, with the middle lobe divided into two long, extended corners. At the base, the lip forms a spur about 0.5 centimeters in size with a nectarium.
The distribution area extends from Morocco in the west through the Mediterranean to southwestern Türkiye and Cyprus in the east. The main distribution area is in the western Mediterranean region.
From sea level it rises to altitudes of 1700 meters. The locations are in full sun to partial shade. The soil is usually alkaline-rich and dry to fresh. A typical location is the calcareous meadows of the Luberon National Park and the Vaucluse plateau.