Thalictrum delavayi

There are a few perennial plants that, despite having a quiet demeanour, stand out from the crowd. Even gardeners whose predilection is for drama cannot help but succumb to their quiet charm.
Thalictrum delavayi is a perfect example. Probably the most attractive of the species, it forms a basal clump of fine 'maidenhair' foliage from which the flower stalks emerge, shooting up and branching as they go. Eventually, the stems form a graceful framework and, at the tips of each, the buds emerge. At first green and clustered, they separate, each with its own slender wiry stem, and change to lilac. Each bud unfolds into a perfect parasol, with creamy white anthers dangling from pendulous stamens. From a distance, the flowers look like a mauve mist hovering among other plants.

A mature, well-grown plant will flower for several weeks. If the weather is cool, the display can last much longer. Almost imperceptibly, the petals fall, giving way to clusters of deep-purple seed pods that lend a different, more subtle, decorative quality. The seed-laden stems are particularly effective in silhouette, although the flowers are best seen against a dark background.
In its native habitat, the plant's height ranges from 2ft to 6ft. In gardens, too, its stature is affected by the cultural conditions, soil, moisture and available light.

Thalictrum delavayi are invaluable for providing a contrast with heavier flowers and especially with spikes and trumpet shapes. They succeed in a broad range of conditions. Any reasonable well drained soil will do, in a sunny position or in dappled shade.

• Awarded the RHS Award of Garden Merit
  Thalictrum delavayi has been awarded the Royal Horticultural Society’s Award of Garden Merit (AGM).

Sowing: Sow February to April / August to September.
Sow indoors in pots or trays at 13 to 16°C (55-60°F), ‘Just cover’ the seed with vermiculite or sieved compost. Sow in trays containing John Innes seed compost, or some similar free draining compost. The compost should be kept moist but not wet at all times. Germination should occur between 15 to 21 days. Thin (prick out) to 7.5cm (3in) pots when seedlings have developed 2 proper leaves and are large enough to handle. Gradually acclimatise to outdoor conditions for 10 to 15 days before planting out. Space 45cm (18in) apart.

Position:
Thalictrums prefer cool places, in semi shade they will grow well in deep soil. If in full sun they will require moist but not wet ground. They need adequate drainage as a site that is waterlogged, even for part of the year, may prove fatal.
No support is necessary when the plants are grown among others, but don't allow plants to be swamped by over-vigorous neighbours, or they will not thrive. In open, exposed areas the plants may need to be supported.

Cultivation:
The foliage and stems start green but soon assume purple tinges. The best colour often results from stress, and pot-grown plants in full sun are sometimes completely purple.
The shape of the plant is spoilt by heavy staking. Give it the protection of a more substantial neighbour on its windward side and plant it among other herbaceous plants that can lend a shoulder to lean on.
To make sure the plants remain vigorous divide them every two to three years as soon as growth begins in spring. (March / April). Larger divisions can be planted out direct into their permanent positions, it is best to pot up smaller divisions and grow them on in light shade in a greenhouse or cold frame until they are growing away well. Plant them out in the summer or the following spring.

Plant uses:
Cottage/Informal, Beds and borders. Shaded Gardens

Origin:
Thalictrum delavayi are native to Eastern Tibet and western China.
One of the characteristics of the genus that differentiates it from many others in its family, the Ranunculaceae, is that the flowers lack nectar-producing structures (nectaries). Other members of the family without nectaries include Anemone and Clematis, but they remain insect-pollinated, while Thalictrum relies on the wind.

Nomenclature:
The genus name Thalictrum is taken from the Greek thaliktron, a name used to describe a plant with divided leaves, and a name given to the genus by Dioscorides, the Greek physician and pharmacologist who wrote the Materia Medica, which remained the leading pharmacological text for sixteen centuries.
The species is named for Père Jean Marie Delavay (1834-1895), a French missionary, explorer and botanist. He was perhaps the first Western explorer of the region which is now encompassed by the Three Parallel Rivers of Yunnan Protected Areas.
Despite their common name of "meadow-rue", Thalictrum species are unrelated to the true rue (family Rutaceae), but resemble its members in having the petiole twice or thrice divided.

Père Jean Marie Delavay (1834-1895)
As a missionary for Missions Etrangères de Paris (Foreign Missions of Paris) his first post was to Hui-chou, east of Canton, in 1867. He spent years exploring the surrounding regions and traveled as far afield as north-west Yunnan. He returned briefly to France in 1881 where he met with Père Armand David and was persuaded to collect for Adrien Franchet at the Muséum National d'Histoire Naturelle.
Franchet had no way of knowing what an incredible plant explorer Delavay would prove to be, as he had only dabbled it botany in the past. When Delavay returned to China in 1882 he based his explorations around Tapintze in the mountains of north-west Yunnan - one of the most botanically rich areas in the world.

Delavay traveled alone. Like Armand David before him, but unlike so many of the plant hunters and explorers who would follow in his steps, Delavay did not employ dozens of porters and packers to carry his equipment and collections. Alone on foot he traversed the mountain ranges seeking alpine species he hoped would be adaptable to western gardens. Also like Armand David, Delavay was very methodical, searching an area with the greatest attention to detail as he went. No plant was too small or insignificant for his notice, and no variation in flower or leaf was too small to be ignored. This dedication resulted in one of the largest collections ever made, constituting a staggering 200,000 specimens representing over 4000 species of mainly alpine flora, of which 1500 were new discoveries.
Of his many discoveries, only a very few were successfully introduced into cultivation. This was largely due to the fact that he collected small quantities of each species found, returning material enough to start only a few specimens at a time. Not until the wholesale collections of Frank N. Meyer, George Forrest and E. H. Wilson would many of his discoveries be truly introduced.

Some of the plants he discovered and introduced are Deutzia dicolor, Deutzia purpurascens, Aster delavayi, Rhododendron ciliicalyx, Rhododendron irroratum, Rhododendron racemosum, Primula forbesii, Primula poissonii, Osmanthus delavayi and lncarvillea delavayi.
Adrien Franchet praised Delavay's collections, and his meticulous notes on every aspect of the materials collected, as among the finest he had ever seen. He published Plantae Delavayanae (1889-90) forever securing Pere Jean Marie Delavay's position in botanical history.
Père Delavay continued his amazing investigation of the flora of north-western Yunnan until 1888 when he contracted bubonic plague. He survived the initial onslaught of the disease, but never fully recovered. This did not stop his explorations, however, eventually he travelled to Hong Kong to recuperate, collecting plants all the way. By 1891 it was clear that a more drastic cure was needed, so Delavay returned to France in hopes of gaining a full recovery.
Unable to stay away, he returned to China in 1893 and continued his collections, adding another 1550 plants to his already impressive total, but in 1895 he finally succumbed to his illness, and died in Yunnan province