I generally do not favour collectors growing potted native orchids, however, as many of these plants are now in private hands, I guess I cannot complain that I had the opportunity to see some of these rare and unusual plants, as potted specimens, being displayed at the recent meeting of the Australasian Native Orchid Society (Illawarra Branch) last week.
The first three species here are all known as Greenhoods, but they are very different in structure, which explains why the very large genus of Pterostylis has been broken up by some taxonomists. The alternative generic names are shown for two of these plants.
Pterostylis baptistii or King Greenhood.
This is a striking plant. i have only seen it in the wild once, in the general Jervis Bay area, growing in a wet, swampy area. But I remember being very impressed by the large size of the flower, and its height. This specimen, a potted plant, was large in flower, but not so tall.
Note how this flower has a classic Greenhood structure with lateral sepals closing off the front of the flower, and with the tips forming points held back and behind the flower. The Labellum is thin, and pointed, and quite red in colour. It resembles a bird's tongue.
Pterostylis gibbosa (Oligochaetochilus gibbosus) (a rare plant, with no common name).
Seen below, this species is classed as rare and endangered. Its population is restricted to several locations in the Illawarra, and a separate population in the Hunter Valley. It has a most interesting structure, with strongly reflexed lateral sepals (the bits below the flower hood) which in other typical Greenhoods, form the front part of the flower. Contrast the front of this flower with the Pt. baptistii above. This one is opened, with the lateral sepals deflexed (downwards pointing).
You can clearly see the yellow pollinia held high inside the partially transparent galea or hood.
This is perhaps the most clear photo I have ever taken of the "hinge" which holds the "labellum", which in this case has been triggered by movement, and has closed up inside the flower. This is the normal position when the plant has been triggered by the presence of an insect (remember I have said that these plants are sensitive to the presenc e of an insect, but they can also snap closed if bumped.) This ability to close is a key strategy for pollination of the flower. The brown section in the centre of the flower is the rear or lower side of the labellum. Immediately below the brown patch is a clearly visible green "strap" of tissue which the botanists describe as a hinge.Pterostylis biseta (Oligochaetochilus biseta). Seen below, this plant is an inland cousin of Pt gibbosa (above). It is a dry land plant. The structure of the flowers of the two species is basically similar.
Its flower is particularly hairy, including on the labellum. This is presumably part of the flower's "trigger" mechanism, as these plants are sensitive to the presence of an insect. It has a very long point on the dorsal sepal (the tip of the hood prokecting forward) as well as two very long projecting tips of the lateral sepals (open, underneath the flower). There is a dead flower in the foreground.Note how prominent the labellum is, on a very free standing 'hinge". The labellum of this plant is green, whereas in Pt gibbosa, the labellum is dark brown.Diuris maculata - Spotted Doubletail. I have still not seen this plant, although it is relatively common around Sydney, apparently.