Nervilia: Care and culture

Terrestrial species

Six species of Nervilia grow naturally in North Queensland, out of approximately 65 species found world wide. This terrestrial genus is found widespread from Africa to Asia, Japan, Samoa and Australia.

The genus is seldom seen in collections, and rarely listed in countries of origin. It appears to be a plant that is not recognised as an orchid, although its close relatives, the genus Pogonia, is a commonly cultivated plant in its native Japan.

Of the six Australian species, four are found close to Townsville, and have been cultivated in a few collections for many years. The four are described below, the typical Nervilia plant being a subterrainian tuber with a single leaf.

During the dry winter months, the plants become dormant, reduced to round white bulbs underground, and should be placed where the pot remains dry, with only an occasional water, normally enough from natural rainfall. Each spring, the bulbs can be repotted just before the leaf emerges. The bulbs should be potted about 2.5cm below the surface of the soil mix. Shade conditions about that for Phalaenopsis.

The basic requirements are a good rich soil mix, with leafmould and some coarse gravel to provide good drainage, and large deep pots to best promote multiplication of the plants, which produce new bulbs on 2 or more adventitious stolons from the underground leaf stem each season.

Each season, with the onset of summer rain and warmth, the larger underground tubers will each send up a flower spike. Each species has its own recognisable flower , and its own distinctive leaf which is produced after the flowers are finished.

Nervilia discolor

This shade growing species has a large round to heart shaped leaf, to 20cm across when well cultivated. The leaves appear "quilted", with raised veins and hairs on the leaf, and tend to hug the ground. The leaf colour is usually green suffused purple, but clear emerald green forms have been seen. This species is internationally wide spread, and in other countries, varigated leaf forms are known. The flowers are usually paired, to 5 cm across, sepals and petals bronze green, the lip purple, crested. Like all Nervilias, the flowers have a similar shape to that of a small rupicolus Laelia.

In bright light, the leaf has a reflective translucence, appearing to sparkle. As a shade lover, this may be a protective mechanism to prevent burning from excess sunlight, by reflecting light from the leaf. It makes an attractive plant when not in flower, and will double and triple its colony size in a season, an excellent specimen pot.

Nervilia holochila

This is a plain pale green leaf, a species found in more open, drier country. The leaf and petiole is up to 20 cm long, about 7cm wide, lance to oval shaped, more or less nearly upright, with longitudinal veins. The flower spike has several flowers, each to about 2.5 cm across, sepals and petals pale green, brown green, the lip white flushed pink.

Once a common species around Townsville, but now hard to find in the large colonies that existed previously, possibly due to the drought conditions over the past years.

Nervilia uniflora

Perhaps a much rarer species than the above, rarely seen in the wild. The original plants came from Ken MacPherson, Proserpine, and have been in continuous cultivation in at least one collection in Townsville for about 30 years. They were collected from road works in the Proserpine area.

The 5cm leaf is very distinctive, heart shaped, on a petiole which sits the leaf 5 to 6 cm above the ground. The top surface is rich green, the underside purple, the margins somewhat wavy. The flowers , to 5cm across, are borne singly on tall spikes, sepals and petals bronze green, the large broad, pointed lip bright pink purple. A showy little plant with charming bright flowers that can triple its colony size in one season with good conditions, and makes an excellent specimen pot. Three small colonies in the wild have been reported near Townsville.

Nervilia peltata

A recently named species that should also be considered rare. It is a small species, the leaf to 3cm diameter, hugs the ground, and is a grey green colour, with 5 or 6 radiating veins, and a sheen from reflective leaf cells. It could be easily mistaken for a grey green mushroom on the forest floor.

The flowers, one or two on a spike, about 2 cm across, are pale green, the lip white. It is the minature of the group, and has a slightly different growing season, emerging later with the wet season and continues to grow after the above species have lost their leaves for winter, a fact that should be noted in its culture.

This species has been known for about 30 years in 2 or 3 small colonies in the Cardwell district. Unfortunately, land clearing and roads have removed all but a few plants in one small colony. It is also recorded from Hinchinbrook Island and from Cape York, and a small colony exists in national park near Ingham.

Culture

The species are easy enough to grow if the following rules are observed. During the cool dry winter, when the leaves have died back, place the pot where it is not watered except for natural rainfall. Repot if possible each season, in spring before the summer rains, using fresh soil mix, leafmould and some coarse gravel, in a deep pot, with good drainage. When in leaf, water heavily, and grow in a very shady position.

A little bark or gravel on top of the potting media stops water splash and soil over the leaves of the species that hug the ground. View your plants occasionally in the sunlight to appreciate the subtle jewel orchid qualities of this genus even when not in flower.