Orchis mascula (Early Purple Orchid)

The specimen above was growing along the edge of a path in a beech-hornbeam-ash coppiced wood. There are several different subspecies of Orchis mascula but in Britain where this specimen was found (in Kent) only subspecies mascula is known to occur. The above specimen is fairly typical of subsp. mascula: the flowering spike is dense with many (up to 45) flowers, the middle lobe of the labellum (lower lip) is about 1.5 times as long as the lateral lobes and, perhaps more characteristically, the lateral lobes are not deflexed (bent backwards by growth). In subsp. ichnusae found in Sardinia, the lateral lobes are deflexed. Characteristic of this species, the labellum elongates into a hollow spur (10-15 mm in length) which usually curves upwards but actually contains no nectar. A hood is formed from the back sepal and lateral petals, with the lateral sepals folded back such that their backs almost touch. The labellum has a lighter white-yellow centre with darker spots. The leaves, which typically form a basal rosette usually (though not always) have purple blotches on them (though some other orchid species have similar spots of anthocyanin pigment). Other than that, Early Purple Orchids are very variable and it is surprisingly easy to be confused by the variety you may see. Some of this variation is shown below.

Below: another spike in the same location several years later (a bit more heavily pigmented this one).

The labella looked white to the naked eye at a distance, but a closer look revealed a tint of purple whichthe camera seemed to pick-up more vividly than my own eye.

Since the extent of anthocyanin pigmentation in the different parts is clearly under independent genetic control, this form could perhaps have arisen from a cross between the all-white var. alba and a purple form.

The variety above is unusual in that the petals are almost devoid of anthocyanins (apart from a tinge at the edges and a few darker spots) whilst the rest of the plant is normally pigmented (including the spotted leaves). I have seen several specimens of this variety at the same location over several years. The color of the flowers of Orchis mascula are notoriously variable, ranging from deep magenta, to reddish violet to rosy pink to white. Var. alba has all white petals and sepals, no spots on the leaves, green stems and bracts and yellow pollinia: it lacks red anthocyanin pigment altogether. Other varieties may have white flowers but still have anthocyanin pigment spots on the leaves. On rare occasions, hybrids between Orchis mascula and other orchids have been found; including other Orchis species, such as Lady Orchid (Orchis purpurea) as well as intergeneric hybrids with Green-Winged Orchid Anacamptis morio (I think I may have seen this hybrid) and Common/Chalk Fragrant Orchid (Gymnadenia conopsea).

The specimen above shows an unusual characteristic for subsp. mascula: the lateral lobes of the labellum are deflexed.

Early Purple Orchids are pollinated by a large number of different insects including bumblebees, cuckoobees and solitary bees and moths. Early Purple Orchid is considered to be a pollinator generalist meaning that it is suited to a wide range of pollinating species. The effects of the different colors and forms of the flowers on the frequencies of pollination by these different species is not known. This situation is not unusual for orchid species. In orchids, the labellum is often particularly variable, perhaps maintaining some evolutionary potential to adapt to different pollinators or perhaps this is a selective response to the local abundance of each pollinator. Abundant pollinators in a given locale have been shown to preferentially pollinate orchid flowers differing, for example, in spur length. Insects need a proboscis long enough to reach the nectar. However, in Orchis mascula there is no nectar!

Although bees may obtain a limited reward from sugary sap in the wall of the spur, it is thought that the plant relies on naive bees for pollination: after a number of failed attempts the bees may learn to avoid this plant type. However, it has also been suggested that the bees may be attracted to other nectar-offering plants that grow in the same habitat, such as Bugle, Ajuga reptans, a flower of the deadnettle family, which does provide nectar and which often occurs in close proximity to Early Purple Orchids. Insects attracted by the Bugle may also visit The Early Purple Orchid, at least until they learn that this offers no reward. This is called the magnet species effect and is its role in Early Purple Orchid pollination is currently being investigated (external link: Early Purple Orchid pollination).

Pollination Mechanism

Under the hood of the Early Purple Orchid flower is the single anther above the mouth of the spur. (The spur is at the base of the labellum or lower lip, of which it is an extension.) When the anther dehisces (splits open) the two pollinia are presented. The pollinia are usually dark green, but are yellow in var. alba. The pollen within each pollinium is grouped into pollen masses, each pollen mass being attached to a central axis by a small thread. The central axis extends into a lower stalk or caudicle with a sticky disc-like foot or viscidium at its base attached to the rostellum (the beak-like end of the column which projects downwards over the mouth of the spur; the column is formed from fusion of the styles, stamen filament and the remaining two vistigial stamens and has the stigma and rostellum at its apex). An elastic flap or bursicle covers the two viscidia and contains sticky liquid beneath it which prevents the viscidia from drying out.

A visiting bee presses against the mouth of the spur, probing for the promised nectar which isn't there with its proboscis. This pressure causes the bursicle to swing backwards pressing one or both viscidia against the head or thorax of the insect. The bursicle springs back, in case only one pollinium was removed, to protect the remaining viscidium. The viscidial fluid hardens after about 30 seconds and after about 1 minute the pollinia, standing upright on the insect, have rotated 90 degrees to point forwards instead. This puts them in a prime position to be pressed against the stigma of the column of the next receptive Orchis mascula flower visited where some or all of the pollen masses (about one third on average) are deposited. The time it takes for the pollinia to rotate into position gives the bee time to find the next flower, favoring cross-pollination. Moths, bees, bumblebees and other insects are thought to acts as pollinators.

Hybrids

Early Purple Orchids have been known to hybridise with a number of other Orchis species, including the Lady Orchid, Orchis purpurea, and very rarely with the Green-Winged Orchid Anacamptis morio (a hybrid I think I have seen) and also very rarely with Common/Chalk Fragrant Orchid, Gymnadenia conopsea. The hybrids tend to produce fertile pollen but have greatly reduced fruit set and reduced seed viability.

Growth and Development

In Britain, Orchis mascula flowers in early spring, and is one of the first northern temperate orchids to do so. It is a  long-lived perennial taking four years or more before first flowering and may live for up to 13 years. It forms two subterranean tubers (each about 10 to 35 mm long) consisting of stem and root tissue (rootstem tubers). At the time of flowering the mother tuber is depleting and is joined by a cylindrical bridge (0.5 to 2.5 cm long) to the second daughter tuber. Older plants have larger tubers and tend to flower earlier. By late summer the leaves die back and the tuber bridge breaks. By this time the daughter tuber is replete with reserves. Periods of dormancy (in which the plant puts out no parts above ground) lasting about a year may occur and plants may not flower every year, especially if over-shaded too heavily. In late winter the rosette of basal leaves emerges and later leaves enclosing the inflorescence bud develop.

Orchis mascula has been described as polycarpic, meaning that an individual plant may flower repeatedly, but it has been suggested that most individuals are monocarpic: flowering once and then dying. The number of flowers on a site can vary enormously from year to year and some years many individuals may produce a rosette of leaves without flowers or remain 'dormant' beneath the soil.

The flowering spike may occasionally be about 2 feet (60 cm) in height and hold up to about 50 flowers. I have seen them this sort of height, if not more, growing in the deep shade of a beech-ash-hornbeam wood.

The Early Purple Orchid begins life as a protocorm, which develops from a seed germinating a few cm below ground. The protocorm relies on a fungal partner to supply it with sugars which it accumulates in a bulbous process called a pre-tuber. By the end of its first year the first leaf emerges and the plant then becomes reliant on photosynthesis to supply most of its sugars.

The variety in flower color pattern and labellum shape is considerable. In a stand of several hundred specimens every individual plant may be distinctly different; sometimes 2 or 3 neighboring stems may look very similar. However, the vast array of labellum types do seem to fit into certain repeating patterns and distinct varieties can be seen.

Early Purple Orchid occurs in a variety of habitats, from grassland to woodland (including oak and beech woods).

Above: the leaves are almost always spotted with purple anthocyanin, but occasional specimens may lack these spots (below):

Click on each image for the full-size version.

Orchids

Article created: 4 Jun 2019; updated: 1 June 2021