Nervilia simplex


Nervilia simplex, commonly known as trembling nervilia or round shield orchid, is a small terrestrial orchid found in South and Southeast Asia and in New Guinea and northern Australia. It has a single short-lived green flower with a white labellum. A more or less circular leaf held horizontally above the ground emerges at the base of the flowering stem after flowering.

Description

The tuber is somewhat round to egg-shaped, across, whitish in colour and sparsely covered with root-knobes, producing only one leaf each year. The leaf measures long and wide and is kidney-shaped to nearly circular, with shallow rounded teeth and a pointed tip. The base is heart-shaped, and the side facing away from the stem is coloured pale green, while the side facing toward the stem is darker green with fine white branched veins and small sparse bristles. The leaf has 7 main veins. The leaf stalk is erect, about long. The flower stalk is produced from the top of the bulb and is held erect, about long, and is green in colour, bearing one flower. The flower bract is small, egg-shaped to lance-shaped, and pointed. The flowers open widely, twisting as they open, and measure across. The sepals are yellowish green with faint grey lines, and are narrow, long and wide, with a sharp to tapering point. The petals are creamy white and narrowly lance-shaped, measuring long and wide. The lip of the flower is strongly reflexed above the middle and is also creamy white, with a light purple mid lobe. This lobe is fringed and white at the base, with a yellowish patch at the centre, and is rhombic in shape, long and wide when flattened. It lacks spurs, and is entire or 3-lobed, loosely embracing the column; the margin at the growing tip is irregularly jagged or fringed, and a ridge extends from the base to the tip of the disk. The column is club-shaped, long, and the tip is relatively large. The stigma is somewhat round. The fruit-stalk is about long, bearing capsules measuring long and wide. The flower's tepals partially cover the capsule even after drying.

Taxonomy and naming

This species was first formally described in 1822 by Louis-Marie Aubert du Petit-Thouars who gave it the name Arethusa simplex in Histoire particulière des plantes orchidées recueillies sur les trois îles australes d'Afrique, de France, de Bourbon et de Madagascar. In 1911, Rudolf Schlechter transferred the species to Nervilia as N. simplex in Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie.
Nervilia simplex is a ground-dwelling plant, growing in open forest floors covered with dry pine needles, at an elevation of. It can be found in the countries India, Nepal, China, Indonesia, Malaysia, Philippines, Thailand, Indo-China, New Guinea, Africa, and Australia.

Variety

A variety of N. simplex, known as var. himachalensis has been described in 2024, but is not as yet accepted by Plants of the World Online. The new variety has leaves long and wide with eleven to thirteen main prominent veins, and creamy-white and purple flowers arranged in pairs on a pale green peduncle.