Autumn lady’s tresses (Spiranthes spiralis) is a tuberous herbaceous perennial. The late summer/early autumn spiraling blooms of this pretty yet delicate orchid resemble a braid of hair, hence the name ‘Lady’s Tresses’. Autumn lady’s tresses is unusual for existing for many years without blooming.
I. Appearance and Characteristics
Spiranthes spiralis, commonly known as autumn lady’s-tresses, is an orchid that grows in Europe and adjacent North Africa and Asia.
Autumn lady’s tresses is a polycarp, perennial, herbaceous plant that remains underground during its dormancy in summer with tubers. The species has thirty chromosomes (2n=30).
- Root
Underground there are two to four (or exceptionally six), egg-shaped or ovate-oblong, hard tubers which are usually 1–3 cm (0.39–1.18 in) long and ¾–1½ cm (0.3–0.59 in) in diameter, slightly tapering towards the tip. They are pale brown and smooth with short transparent hairs on the outside. These tubers, as in many orchids, have an earthy musty smell, originating from the mycorrhiza. There are no thick filamentous secondary roots as in many other orchids.
- Stem
The plant needs many years to grow large enough (eight years) to produce above-ground parts, and to produce a flowering stalk (another three years). Even then, it mostly flowers once every few years, and will during hard times not surface at all. The stem is grayish green, usually 7–20 cm (2.8–7.9 in) (in Southern Europe exceptionally 40 cm) high, unbranched, erect, and terete. Especially further up, the stem is covered with short transparent glandular hairs. Below the flowers stand three to seven grayish green, acute leaves that envelop the stem, with membranous edges and three to five veins. Sometimes the withered leaf remains of the rosette of the previous year are still visible at the base of the stem.
- Leaf
The new leaves, which appear at the same time or after the flower stem, stand with four to five together in a rosette beside the stem. They are 2–4 cm (0.79–1.57 in) (exceptionally 5½ cm) long and ¾-1¾ cm (0.3-0.69 in) wide, blue-green, very glossy, sessile, oval and have a pointed tip and translucent entire edges. They have three to five keeled veins. Plants in the Mediterranean can be considerably more robust than those in Western and Central Europe.
- Inflorescence
The inflorescence is a slender spike of 3–12 cm (1.2–4.7 in) (exceptionally 20 cm) long, with usually ten to twenty-five (rarely as few as six or as many as thirty) flowers. They are set in a single row, usually in a clockwise or counterclockwise spiral winding around the axis, or rarely all to one side.
- Flower
Each flower is subtended by a pale green, lanceolate bract. This shelters the base of the flower, tapers, bends toward the tip, has white edges and scattered glandular hairs at the base. They are usually 9–13 mm (0.35–0.51 in) long and 3–5 mm (0.12–0.20 in) wide. The flowers are very small, ± ½ cm (0.2 in), white, and spread a fragrance that is said to be reminiscent of lily of the valley, vanilla or almonds. The flowers produce nectar unlike in many other orchids. The flower has no spur.
- Perianth
Outer sepals are oblong-ovate, slightly tapering to a blunt tip, 6–7 mm (0.24–0.28 in) long, white with a light green vein, have a ciliate or very finely serrated edge, and on the outside with little glandular hairs. Inner perianth leaves are white, elongate with a blunt tip, a vein and adhere with the slightly longer upper outer perianth leaf, thereby forming an upward decurved upper lip.
The lower lip is pale green with a wide irregular jagged edge of crystal-like transparent white growths, oblong, approximately 4–5 cm (1.6–2.0 in) long and 2½–3 mm (0.10–0.12 in) wide, trough-shaped, rounded and without lobes and at its top bending down. Both lips give the flower as a whole a trumpet shape. The lower lip encloses the column (merger of the stamen and style) at the base, and there are also two white, glossy, round, nectar-secreting glands, each with a ring of papillae around their base. The small column is green.
- Fruit and seed
The capsule is 5½-7 mm (0.22-0.27 in) long, 2–4 mm (0.079–0.157 in) or occasionally up to 5 mm (0.20 in) thick, oval shaped, and filled with countless tiny and very lightweight seeds of 0.5–0.6 mm (0.020–0.024 in) long at 0.1 mm (0.0039 in) thick.
- Growth cycle
Around the end of August a rosette of leaves appears, which stays green over the winter and dies back in July at the latest. During the following weeks, a flower stalk emerges from the centre of the dead leaf rosette, and during flowering, one or two new rosettes are formed.
Autumn lady’s tresses blossoms after the summer (August–October). The species is not self-pollinating. The pollination is done by bees and bumblebees. In nature, less than half of the fruit capsules produce seeds. The very fine seeds are dispersed by the wind in October or November. Nevertheless, most seeds will not disperse more than a few dm from the mother plant since the vast majority of new plants are in close vicinity to an adult plant.
Autumn lady’s tresses spreads primarily through sexual reproduction. However, the plants to a limited extent also propagate vegetatively by the formation of side buds on the underground stem. The new plant forms its own tuber and leaf rosette, and if the old root dies, the connection between the two daughter plants is broken. The plants therefore often occur in small dense groups. An individual plant does not usually flower every year, apparently because the production of seeds takes a lot of effort. Plants do not necessarily appear above ground each year, so that after an absence mature plants suddenly seem to appear out of nowhere.
- Differences from other species
The genus Spiranthes contains about forty species, most of which are from North America. Some species are found in Central and South America, in temperate and tropical Asia southward to Australia and New Zealand. In Europe, three species occur in the wild. Besides the autumn lady’s tresses, these are the summer lady’s tresses S. aestivalis, and the Irish lady’s tresses S. romanzoffiana, a mainly North American species that also occurs in Ireland and western Scotland.
The autumn lady’s tresses are easily distinguished because the two other species have inflorescences that occur earlier during the year (May–July) from a living rosette, with lanceolate leaves rising at an angle and having cream-colored instead of greenish or greyish white flowers. The autumn lady’s tresses also resemble the evergreen Goodyera repens (creeping lady’s-tresses or dwarf rattlesnake plantain), which has a creeping rhizome rather than tubers. In G. repens the inflorescence emerges from the centre of a rosette of ovate leaves with a pointed tip, and has striking perpendicular connective veins. The flowers are covered in long hairs that are often tipped with tiny droplets.
Autumn lady’s tresses may be found on quite different substrates, from weathered chalk and limestone to sand and gravel in dunes and slightly acidic heathlands. Occasionally, it has also been found on clay on sloping sites. It sometimes occurs in lawns, and was reported from the top of a wall in Sicily. Soils need to be low in nitrogen and phosphorus and neither dry nor wet.
II. How to Grow and Care
Sunlight
Autumn lady’s tresses thrives in conditions where full sun is available, as it requires a high intensity of light for optimal growth and flowering. The duration of light should ideally be consistent with the plant’s natural habitat, which suggests long hours of daylight. While autumn lady’s tresses prefers full sun, it tolerates partial sun to some degree, meaning it can still grow in locations where sunlight is filtered or obstructed part of the day. Deviations from full sun to lower light levels may result in less vigorous growth and a potential reduction in blooms.
Autumn lady’s tresses’s leaves may exhibit adjustments in orientation to maximize light absorption. For outdoor planting, autumn lady’s tresses should be positioned in a spot where direct sunlight is predominant. The plant’s adaptation to specific light environments highlights its resilience, though adherence to its preferred light conditions will yield the healthiest specimens.
Temperature
Orchid plants are native to tropical and subtropical regions, preferring warm, moist conditions. Optimum growth temperatures are between 18 to 28 ℃, and it’s best if there is a certain difference in temperature between day and night: for example, 20 to 25 ℃ during the day and 15 to 18 ℃ at night. Autumn lady’s tresses is a drought-tolerant plant, but cannot tolerate waterlogging, and grows well at 50-70% humidity. If the leaf tips are withered, it means the environment is too dry. Use a humidifier or spray bottle to increase the air humidity.
Watering
Originating from temperate regions, autumn lady’s tresses is accustomed to moderate moisture levels and can endure brief periods of dryness. This species thrives with consistent hydration but tolerates occasional fluctuations in water availability. Watering every week suits its needs, maintaining soil moisture without causing waterlogging. Typically grown outdoors, autumn lady’s tresses has a growing season that aligns with its watering needs, ensuring it receives adequate moisture when it’s most crucial for its development.
Soil
The “soil” required for autumn lady’s tresses is special because, as an epiphyte, it originally grew on big trees in tropical forests. You need to mimic this growing environment with, for example, water moss, wood chips, coconut shells, volcanic stones, or perlite as soil substrate. You can also buy orchid-specific soil directly from gardening stores.
Fertilizing
For autumn lady’s tresses, a balanced nutrition fertilizer promotes growth and flowering. Fertilize bi-monthly during active growth with a diluted solution, appropriate to pot size. Seasonal variations may require adjustments, decreasing in dormancy. Handle with care to prevent root burn. Practical tip: Water before fertilizing to aid nutrient absorption and distribution.
Planting Instructions
You do not need a large pot to grow an autumn lady’s tresses as it won’t produce a vigorous root system that occupies much space. If the pot is too large, the soil tends to collect water and cause root rot. The height of the pot should be 2.5 cm taller than the (pseudo)bulb of the autumn lady’s tresses. You can easily buy autumn lady’s tresses in a local gardening store and simply place it in breathable, well-drained substrate. After planting, use upright sticks to support flowering branches. In warm, humid climates, cover the root of autumn lady’s tresses with sphagnum moss and attach them to a tree with strings.
Pruning
It is best to prune wilted autumn lady’s tresses flowers promptly after blooming to reduce unnecessary nutrient consumption and promote more blooms. Trim withered and diseased leaves promptly to increase air circulation, thus reducing pests and diseases.
Propagation
Autumn lady’s tresses is a perennial orchid that thrives in well-drained soil and partially shaded locations. Successful propagation is typically achieved through division, a straightforward process where clusters of pseudobulbs are carefully separated during the plant’s dormant period. Gardeners should replant the divisions promptly, maintaining soil moisture without waterlogging to encourage root establishment and growth.
Transplanting
For autumn lady’s tresses, the sweet spot for root relocation is when late spring warmth kisses early summer, fostering optimal growth. Choose well-drained spots, bathed in dappled light. Gentle handling bolsters success, nurturing these delicate perennials.
III. Uses and Benefits
If you want to display autumn lady’s tresses flowers in vases, harvest there are only 2-3 flowers blooming on the stem. Cut diagonally at the bottom of the flower stem, and place it in a vase immediately. You can enjoy the cut flower in clean water for about 14 days, or for a longer time with preservatives.
