If you go down to the woods today I can guarantee that you won’t see Yellow Bird’s-nest, Hypopitys monotropa. But go back in summer and, if you’re lucky and it’s the right kind of woodland, you might see this curious and subtly beautiful flower.

Yellow Bird’s-nest, Hypopitys monotropa. Speyside, June 2024.

Yellow Bird’s-nest swaps its names

Scientific names of plants have a habit of changing and recent DNA studies have caused a swap around of Yellow Bird’s-nest’s generic and specific names from Monotropa hypopitys to Hypopitys monotropa. Yellow Bird’s-nest has switched families too. Older floras list it as a member of the Monotropaceae or Pyrolaceae (along with Wintergreens) but all these are now considered to be members of the Ericaceae, the Heather family (note 1).

I first saw Yellow Bird’s-nest growing under Beeches in Thetford Forest in July 2021. The Beech leaves cut out bright the summer sunlight from the woodland floor and the plant’s flowers looked eerie and mysterious in the gloom.

Yellow Bird’s-nest, Hypopitys monotropa. Thetford Forest, July 2021.

Food from fungi

Yellow Bird’s-nest is a rather strange plant.

It is a perennial with no leaves or true stem and it doesn’t manufacture its own food by photosynthesis, but it isn’t a direct parasite on plants either, unlike the Broomrapes, Orobanche (note 2).

Yellow Bird’s-nest was once thought to be saprophytic, obtaining its nutrients from decaying organic matter. But Hypopitys monotropa is actually a myco-heterotroph, a parasite that obtains its food from a fungal partner, various species of fungus in the genus Tricholoma. Tricholoma species (Knights) form mycorrhizal relationships with their host trees, trading nutrients and water for the sugars the tree manufactures by photosynthesis. Yellow Bird’s-nest has need of some of these sugars too, so it is an indirect parasite on the trees, via its fungal host.

In 2004 a study demonstrated that Yellow Bird’s-nest associates with the ectomycorrhizal fungus Tricholoma cingulatum (Girdled Knight) under willow trees (Salix) and with its relative Tricholoma terreum (Grey Knight) under pines (Pinus) (note 3). There are many more species of Tricholoma, associated with other species of trees and presumably Yellow Bird’s-nest parasitises some of these other fungi too.

Grey Knight, Tricholoma terreum, under pines at Holme-next-the-Sea, November 2019.

Where to find Yellow Bird’s-nest

Yellow Bird’s-nest flowers from June to August in the British Isles. (The Wild Flower Finder website has a good selection of photographs.)

In Norfolk, I’ve seen Hypopitys monotropa under Beech (Fagus sylvatica) trees in Thetford Forest and beneath pine (Pinus) trees at the back of Holkham Beach. The latter sighting was in the drought and extreme heat of July 2022, which did no favours to the dying, drying flower heads.

Yellow Bird’s-nest, Hypopitys monotropa. Under pines at Holkham, frizzled up in the drought, July 2022.

The BSBI Plant Atlas shows the distribution of Hypopitys monotropa in the British Isles. The plant is widely distributed but it becomes increasingly rare towards the north and west. It is absent from the Isle of Man, the Isles of Scilly and the Northern and Western Isles. It suffered substantial losses in the 19^th and early 20^th centuries and it seems to be declining still.

Yellow Bird’s-nest is not an easy plant to monitor, because it doesn’t necessarily flower every year, and this has probably led to under-recording, especially in Ireland.

In Ireland, Northern Ireland has more than half the records and it grows mainly in County Fermanagh, with isolated sites in County Londonderry and County Antrim. It is listed as rare in the Irish Red Data Book and on the British mainland it is “not quite a Nationally Scarce species“.

There are two subspecies of Hypopitys monotropa in the British Isles (subsp. monotropa and subsp. hypophegea). They differ in chromosome number and some features of the flower. Stace’s Flora (note 1) gives full details, as does the Wild Flower Finder website.

The best places to look for Yellow Bird’s-nest is in the leaf litter of shaded Beech and Hazel on calcareous soils, under pines on more acid soils and in dune slacks with Creeping Willow, Salix repens. The association with Tricholoma fungi is key, though you’ll usually need to visit in autumn to see any fruitbodies.

The other place I’ve seen Yellow Bird’s-nest was near Aviemore, in June 2024. It was growing in mixed woodland with plenty of pines and they were the brightest, freshest specimens I’ve seen. The light was good too, so I took several photographs, including the one at the top of this page (note 4).

Yellow Bird’s-nest flowers apparently smell of honey, so I must take a sniff next time I see some.

Hypopitys monotropa worldwide

Hypopitys monotropa grows in the temperate zone of the Northern Hemisphere and is native throughout Europe, Asia and North America, reaching into Central America. It can flower from April to December, depending on where it grows. 

In North America, Yellow Bird’s-nest flowers from May to October. It is listed as endangered in Florida and threatened in Iowa.

In Britain our plants are yellow but in North America plants that flower in summer have sparsely hairy yellow flowers and those that flower in autumn have densely hairy red flowers. There are some lovely photographs of American plants on the USDA Forest Service website.

In North America Hypopitys monotropa is known as Dutchman’s Pipe and Pinesap. (Another name is False Beech-drops.) “Pinesap” refers to the plant’s habit of growing under pines, as does the generic name: from Latinized Greek hypo-, “under”, and pitys, “pine”.

Notes

Note 1 – I am using the Fourth Edition of Clive Stace’s “New Flora of the British Isles“ (2019), where Hypopitys appears on page 567.

Note 2 – I have written about a couple of species of Broomrape: Ivy Broomrape (Orobanche hederae) in June 2016 and Purple Broomrape (Orobanche purpurea) in January 2016.

Note 3 – See the study by Leake JR, McKendrick SL, Bidartondo M, Read DJ. “Symbiotic germination and development of the myco-heterotroph Monotropa hypopitys in nature and its requirement for locally distributed Tricholoma spp.” New Phytol.  Vol 163(2): pp405-423 (2004).

Note 4 – There is no dot on the map in the BSBI Atlas for Speyside but I have been told that it is a known site for the plant.