About Pterostylis alata (Labill.) Rchb.f.
Pterostylis alata (Labill.) Rchb.f. is a terrestrial, perennial, deciduous herb that grows from an underground tuber. When it is not flowering, it produces a rosette of dark green, wrinkled leaves that measure 4–20 mm long and 3–12 mm wide. Flowering plants bear a single flower on an 80–250 mm tall spike; the flower itself is 17–21 mm long and 6–7 mm wide. The flowers are white with dark green stripes. The dorsal sepal and petals are fused together to form a hood, also called a "galea", that covers the column. The dorsal sepal curves forward, ends in a narrow point 2–5 mm long, and has a brownish tint near its tip. The lateral sepals are held tightly against the galea; they have erect, thread-like tips 23–27 mm long, and a broad V-shaped notch, called a sinus, between their bases. The labellum is 10–12 mm long, approximately 3 mm wide, brown, and curved, and it protrudes above the sinus. Flowering takes place from May to August, with peak flowering occurring in June and July. This species grows in open forest and coastal scrub in Tasmania. It does not occur on the Australian mainland; plants that were formerly classified as this species are now recognised as a separate species, Pterostylis striata.
