Pterostylis nutans or nodding greenhood, an Australian

This item adds a bit of foreign flavour! It is an Australian orchid found in great numbers on some roadsides on the outskirts of Melbourne, noticed in July during Covid-19 lockdown.

Pterostylis nutans, commonly the nodding greenhood or parrots beak orchid, is a winter growing perennial reaching heights around 30 cm. Above-ground plant parts return annually from the underground, nearly spherical tuber.

This growth consists of three to six ovate leaves, about 9 cm long, grown in a basal rosette and an erect stem bearing a green, pendulous, hooded flower, about 2,5 cm long. The hood or biggest part of the visible flower comprises the upper three tepals of the resupinate (twisted around) corolla. They are the dorsal tepal and the pair of lateral petals bending protectively or modestly over the male and female floral parts, concealing them. The specific name, nutans, is derived from the Latin verb nutare meaning to nod, referring to this orientation of the hood.

Beside the hood, the narrow, lateral sepals curve up conspicuously, their tips passing it. There is a sheathing bract over the ovary at the back. Flowering happens in winter to after midspring.

The species distribution is from the southeast of Queensland, eastern New South Wales and Victoria to the southeast of South Australia, also found on Tasmania.

The habitat is damp, undisturbed areas in rainforest, eucalypt forest and scrubland.

Greenhood orchids of the Pterostylis genus comprise about 300 species. They are deciduous, terrestrial, tuberous perennials found in Australia, New Zealand, New Guinea, New Caledonia and an Indonesian island.

Flower colour is mostly green, sometimes striped brown, red or white, the flower structures and pollination mechanisms distinctive. Greenhoods are pollinated by insects, mostly small flies, gnats and mosquitoes.

Apart from setting seed, the plants tend to form colonies from vegetative propagation of small new tubers adjacent to the main one. The dehiscent greenhood fruit capsules add solid contributions as well: in some species about 500 seeds may be released from one ripe capsule. Some of these plants are grown commercially and information about how to do this is freely available on the Internet (Wikipedia; www.oznativeplants.com; www.nurseriesonline.com.au).