Sometimes growing only about 20 cm tall, and at other times reaching a height of about 80 cm, the Tall Greenhood Pterostylis melagramma is a common sight in winter throughout the district.
A few plants often grow in close proximity to each other, but this species is not a colony former. It reproduces only from seed, with each plant developing a replacement tuber each season, but no additional tubers are formed.
One to twenty, small, translucent green flowers, with indistinct stripes, open at the top of the flowering stalk. Small, dark-green leaves, to 8 cm in length, are spaced along the lower section of the flowering stem, and there is no basal rosette. Non-flowering plants are often seen near the flowering plants. These are recognisable by the small rosettes of pointed dark-green leaves on short stalks.
A second species of tall greenhood, the Green-striped Greenhood Pterostylis chlorogramma is also found in the district.
This orchid is listed in the Australian Government’s Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and Victorian Flora and Fauna Guarantee Act 1988 (FFG Act) as a vulnerable species. Known from a very few sites, this orchid, at first glance, could be mistaken for P. melagramma, but there are some distinct differences.
The hood of P. chlorogramma is larger and translucent green with darker green stripes. It curves forward from the base in an irregular semicircle, somewhat bulbous in the basal half. The flower of P. melagramma is much flatter, and, as we have said, less distinctly striped. The labellum of P. melagramma has a dark brown stripe down the centre, hence the term ‘melagramma’ meaning dark line. The labellum of P. chlorogramma usually has a dark-green stripe on the labellum, hence the term ‘chlorogramma’ meaning green line. The lateral sepals, which point downwards, are also a little different – those of P. melagramma are slightly curved, while those of P. chlorogramma have straight margins. The petals, which can be seen underneath the hood, also, are much more flanged in P. chlorogramma, meeting at the base of the flower.
Other winter orchid species that have been seen flowering include Slaty Helmet Orchids Corybas incurvus; Gnat Orchids Cyrtostylis reniformis; and C. robusta. Other species of greenhoods seen are; Dwarf Greenhood Pterostylis nana; Blunt Greenhood P. curta; Trim Greenhood P. concinna, and, of course, our familiar Nodding Greenhood P. nutans which is forming large colonies throughout the district. The first of the Mayfly Orchids Acianthus caudatus, and the Leopard Orchids Diuris pardina have also appeared.
After all this great rain we are awaiting some sunshine to encourage our spring flowering orchids to develop, and the flowers to open.
Photos and descriptions of all the orchids that grow in the Anglesea district are documented in Orchids of the Anglesea District available from ANGAIR.