Himantoglossum Spreng.

Four species distributed in western, central, and southern Europe and North Africa, eastwards to Turkey, the Caucasus, and southwest Iran. (JW).

Himantoglossum is confined to dry calcareous soils throughout its range. In southern England, for example, H. hircinium is primarily found growing on chalk downland but also occurs in the limestone areas of Gloucestershire and Oxfordshire and has been recorded from the sandy oils of stabilized sand-dunes in England, Holland, and France (Summerhayes 1951).
Himantoglossum normally grows in full sun to semi-shade in grassland, meadows, shrubland, garrigue, rough hillside pastures, and open woodlands comprising oak, juniper, or pine (Delforge 1995). Members of the genus are also frequently found growing in disturbed habitats such as railway embankments, roadside verges, and chalk pits (Davies et al. 1988; Rasmussen 1995). ln habitats with scrub and tall grass (such as some English downlands) orchids that frequently co-occur with Himantoglossum are Gymnademia conopsea, Dactylorhiza fuchsii, and Anacamptis pyramidalis (Summerhayes 1951 ). On stabilized sand-dunes it is often accompanied by Anacamptis pyramidalis and Allium oleraceum L. (Alliaceae; Lang 1989). In addition to growing at sea level in coastal locations, Himantoglossum also occurs in mountainous areas at elevations of up to 1800 m (Delforge 1995).
Plants flower in different parts of the range between April and August. For example, H. hircium starts to flower in April in southern Europe, whereas in Britain it flowers in the summer in late June to early July. At the time of flowering, the lower leaves have usually withered as their water was uti lized in the expansion of the inflorescence in the spring (Summerhayes 1951; Davies et al. 1988; Lang 1989). These leaves were formed in the previous autumn and remained green throughout the winter ('winter-green'). Following flowering and fruit-set, the whole plant senesces and survives underground as a tuber. Mycotrophic roots develop from the tuber in the autumn prior to the re-appearance of the aerial stem in the winter (Fuchs and Ziegenspeck 1925, cited in Rasmussen 1995).
Fruit-set levels of up to 30% are reported for l-1. hircinnm (Lang 1989), and even solitary plants usually set some fruits (Summerhayes 1951). However, fruit-set varies from year to year, as recently demonstrated by a study population in Kent in southern England (Carey 1998). In 1994 each plant produced at least five capsules, but in the following year most inflorescences failed or aborted before pollination such that few fruits were produced. It has been estimated that each capsule of H. hircinum contains about 1200 seeds (Summerhayes 1951). Lang (1989) suggested that seed production is an important means by which the plant has spread across England. At the local level, Carey (1998) also attributed the marked spread of H. hircinum at a site in Kent in southern England over a 20-ycar period to seed dispersal.
Germination of Himantoglossum seeds and development of a protocorm probably occurs rapidly in the field, that is by the autumn following seed dispersal (Ziegenspeck 1936, cited in Rasmussen 1995). The first tuber is formed from a bud in the axil of a scale leaf at tl1e tip of the protocorm during the first spring after seed germination. At the tip of the tuber, a short rhizome with roots develops in the second autumn, and a second tuber begins to grow, which reaches full size in the early summer. The rhizome and roots a re mycotropbic and may be infected with a diverse range of endophytes. For example Gaumann et al. 1961 (cited in Rasmussen 1995) isolated 15 fungi from the roots of H. hircinum, 14 of which were identified as Ascomycetes and one as Rhizoctonia versicolor. The only part of the plant to survive the summer resting period is the second tuber, as the rhi zome, roots, and first tuber have senesced by that time. The annual underground cycle of rhizome, root, and tuber development is repeated again for at least another year before the first leafy stem emerges above the ground, such that newly emerged plants in any population of Himantoglossum are at least two years old (Ziegenspeck 1936, cited in Rasmussen 1995). Seedling establishment and maturation of the tuber are influenced in different ways by summer weather conditions. Whereas high precipitation levels in the summer promote establishment of Himantoglossum seedlings, they have an adverse effect on tubers, sometimes causing them to rot and thus may lead to the death of mature Himantoglossum plants following flowering (Voth 1980, cited to Rasmussen 1995).
Throughout its range Himantoglossum is usually local and rare. Even the most widespread species, H. hircinum, is rare throughout most of the Mediterranean (Davies et al. 1988; Summerhayes 1951) with a localized occurrence in north Africa and absence from southern Italy (Delforge 1995). It is most abundant in western France, where it can sometimes be found in large numbers, probably because of its apparent preference for an oceanic climate (Summerhayes 1951). Similarly, the other species in the genus are all locally distributed and in most cases also rare (Davies et al. 1988). The only species that occurs in the UK is H. hircinum where, as in much of the rest of Europe, it is rare and sporadic in its occurrence. In most cases, only solitary plants are found, but sometimes larger populations have been recorded such as one population of over 200 plants in Kent (Summerhayes 1951). They can be unpredictable in their appearance above ground and inexplicably disappear after flowering successfully for a number of years in succession (Davies et al. 1988; Lang 1989).
The history of the distribution of H. hircinum in Britain is unusual compared to that of other British orchids, most of which have shown a marked decrease in occurrence in recent years (Hutchings 1989). The earliest record of H. hircinum is from 1641 for several localities around Dartford and Crayford in Kent. These populations persisted for the next 200 years, but in about 1850 the species died out in the area (Summerhayes 1951; Lang 1989). During the latter half of the 19th century, H. hircinum was found in an additional 20 localities in south-east England, mostly on the North Downs in Kent, Suffolk, and Hampshire. Because these were small and short-lived populations, it was still considered an extremely rare species in England and threatened with extinction from the British Isles. At the beginning of the 20th century, however, the frequency of occurrence of H. hircinum began to increase. Between 1900 and 1933, another 129 stations were found including sites well outside its previous limits in soum-east England, as far north as Yorkshire and as far west as Devon. Although many were for single plants that failed to persist for more than one or two years (Perring 1974), this still represented a considerab le increase in me spread of the species mroughout England, which Good (1936) explained as the result of an alteration in climatic conditions. Meterological records showed mat between 1900 and 1933 me climate became more equab le, slighdy warmer in winter and cooler in summer than prior to 1900. Good suggested that this change toward a more oceanic type of climate, such as mat encountered in western France, allowed the species to grow in greater numbers and spread to a wider variety of sites throughout England (although in recent years doubts have been cast as to the likelihood of this explanation, which has never been tested experimentally; Willems 1982). A sensitivity of H. hircinum to changes in climatic conditions might also explain why the English distribution of the species has declined since the 1940s such that it was reduced to just nine sites (Perring 1974) and today is a Red Data Book species.
In Britain and elsewhere in its distribution Himantoglossum is also susceptible to human disturbance. One possible explanation for the disappearance of some populations is excessive gathering by collectors (Summerhayes 1951). One colony that had flourished in Bedfordshire between 1938 and 1947 was subsequendy destroyed by ploughing (Lang 1989). In Turkey, Himantoglossum is threatened by collection for production of ice cream (Delforge 1995). (RN).

Robust herbs. Rootstock tuberous, tubers large, ovoid or ovate-oblong, entire. Stem erect, leafy, glabrous. Leaves often large, oblong-ligulate, unspotted. Inflorescence densely or laxly many-flowered, broad; floral bracts membranous, equalling or shorter than floral hood. Flowers large, greenish to purplish. Sepals and petals connivent to form an obtuse hood. Petals narrow. Labellum spurred, three-lobed, much longer than hood, side lobes short, obliquely linear to triangular-falcate, margins undulate, mid-lobe long, linear, strap-shaped, often deeply bifurcate and spirally twisted. Column short; rostellum prominent, lamellate; stigmatic cavity quadrate to circular, shiny; lateral appendages small, verrucose; anther obtuse; pollinia two, caudicles attached to a single viscidium, enclosed in a large, hemispherical bursicle. Ovary sessile, twisted. (JW).