Note that the darkly striped tongue (labellum) below the hood is apparently missing from some flowers. The labellae of the greenhoods are so-called irritable members, meaning that they react to the touch of an incoming insect. The tongue of this group of greenhoods is particularly sensitive, trapping the insect within the hood, from which the insect's struggle to escape facilitates cross-pollenation. Compare with Gurdies Point Pterostylis melagramma, taken 15th August 2002. P. smaragdyma is a rare close relative of P. melagramma.