The stunning Meadow Clary (Salvia pratensis) has near-threatened status in Britain The endangered Field Cow-wheat (Melampyrum arvense) is found at only four sites nowadays Clustered Bellflower (Campanula glomerata)
Cowslips (Primula veris) seem to be increasing Yellow Rattle (Rhinanthus minor) is a great tool for the conservationist Pyramidal Orchids (Anacamptis pryamidalis)
Common Spotted Orchid (Dactylorhiza fuchsia) Bee Orchids (Ophrys apifera) are self-pollinating Fragrant Orchid (Gymnadenia conopsea) and Meadow Grasshopper
Man Orchid (Orchis anthropophorum) on the North Downs Close-up of a Man Orchid, showing why the plant has that name White Helleborine (Cephalanthera damasonium)
Common Toadflax (Linaria vulgaris) is known as Butter and Eggs Yellow-wort (Blackstonia perfoliata) flowers close when the sun goes in Carline Thistles (Carlina vulgaris) do not grow very tall
Birdsfoot Trefoil (Lotus corniculatus), or Eggs and Bacon Broad-leaved Everlasting Pea (Lathyrus latifolius) Field Scabious (Knautia arvensis) and Common Blue

Unimproved calcareous grassland is a tough habitat but a rich one for flora, much of which hugs the ground to fit the soil conditions and effects of the wind. This aims to be a representative selection.

The handsome and stately Meadow Clary (Salvia pratensis) is not only one of the most striking downland flowers visually - it is also one of the rarest, with 'near-threatened' status. They flower in June and July and are found at only around 20 sites in Britain, mostly on the North Downs and in Oxfordshire.

Field Cow-wheat (Melampyrum arvense) is also a plant of calcareous grassland and an even scarcer one, classified as endangered. Never very common in Britain, it is found in only a handful of places nowadays, in Wiltshire, Bedfordshire and on the Isle of Wight. Field Cow-wheat flowers from June to September and is a hemi-parasite, gaining nutrition from other plants to which its roots are attached.

Clustered Bellflower (Campanula glomerata) is related to Harebell (Campanula rotundifolia) but is much vivider in colouring and much less widespread - it is a downland plant par excellence, flowering until well into autumn.

At the other end of the flowering period, Cowslips (Primula veris) are a fine sight in spring and appear to be increasing.

The plant species most closely associated with the habitat, though, and the one which packs human visitors in like no other, is the Orchid.

Orchids are handsome and artistic, in the sense that they can resemble anything from insects to monkeys, reptiles and soldiers. They are also mysterious,Self-heal (Prunella vulgaris) is found in many habitats with a remarkable life cycle that allows vast numbers to appear one year and few the next, with blooming not necessarily occurring more than once a decade.

Warmer summers may well encourage Orchids to flourish - the Lizard Orchid (Himantoglossum hircinum) was thought extinct in 1900 but then expanded in the warm period 1920 to 1940 before contracting again when it grew colder, then tripling to more than 3,000 plants from 1988 to 1994.

June is the best month to see Orchids, and in a good year, such as 2004, the downs can be alive with them. Among the commoner ones are the Common Spotted Orchid (Dactylorhiza fuchsia), which is at home in various other habitats, the Pyramidal Orchid (Anacamptis pryamidalis), the Fragrant Orchid (Gymnadenia conopsea) and the Bee Orchid (Ophrys apifera).

Both the latter two species can be found in damper places as well, but they are in their element in short turf on lime or chalk. Bee Orchids, which originally were designed to attract bees for pollination as happens in the Mediterranean but are now self-pollinating, can turn up in hundreds, often in unexpected spots such as roundabouts. Whether they repeat the performance the year after, or wait a lot longer, is never certain.

Man Orchids (Orchis anthropophorum) are not quite so common, found most easily on the North Downs in Kent, and the White Helleborine (Cephalanthera damasonium), like nearly all of that particular genus, is associated with woodland. The pictured plant, along with a number of others, was photographed in the open on the North Downs near Dorking but there is woodland nearby.

Meadow Grasshoppers (Chorthippus parallelus, 18mm) are among species of grasshopper and cricket that use flowers for gaining a good vantage or 'jumping off' point. Orchids are often appreciably taller than the other flora found on downland and are ideal for this.

Field Scabious (Knautia arvensis), which can grow much higher, helps perform a similar function and provides a perfect warming-up spot for Common Blue butterflies (Polyommatus icarus, wingspan 35mm) among others as the sun hits a south-facing slope fairly early in the morning.

Yellow Rattle or Cockscomb (Rhinanthus minor) is a tremendously useful hemi-parasitic herbaceous annual plant that gains some of its nutrients from the roots of neighbouring plants.Deadly Nightshade (Atropa belladonna) in flower It grows to 25-50 cm tall, and the fruit is a dry capsule, which contain loose, rattling seeds when ripe. It is ideally suited by dry fields or meadows, including downland, and is in bloom from June to September. Research at the Centre for Ecology and Hydrology indicates that encouraging Yellow Rattle in hay meadows greatly increases biodiversity by restricting grass growth, permitting other species to thrive.

Yellow-wort (Blackstonia perfoliata) is a pretty common member of the gentian family found on calcaerous soils and dunes. It needs full sun to thrive; the flowers close when the sun goes in. Yellow-wort is in bloom from June to October.

Carline Thistles (Carlina vulgaris) are found mostly on calcareous grassland and do not grow so tall as most Thistles, to 50cm. The flowers look very similar when dead as when in bloom in late summer, and can survive all winter.

Self-heal (Prunella vulgaris) is universal, at home in lawns and woods and flowering from June to October, but nowhere does it look better than on downland.

Common Toadflax (Linaria vulgaris) is a spreading plant, similar to the well-known Snapdragon in gardens, that grows well on loose, well-drained soil in sun or partial shade. One colloquial term for the flowers is Butter and Eggs. In similar vein, but from a different family (the Fabaceae or pea family) is Birdsfoot Trefoil (Lotus corniculatus). The mixture of yellow and orange petals, leading to the colloquial name Eggs and Bacon, makes the species striking and they can carpet swathes of downland for much of the summer. It is a foodplant of the Dingy Skipper (Erynnis tages) butterfly. Vetches and Trefoils are very successful on calcareous grassland.

Among naturalised plants from the same family which sometimes occur on downland, Broad-leaved Everlasting Pea (Lathyrus latifolius) is one of the handsomest and most useful for fauna. It acts as the foodplant for a non-native butterfly that turns up now and then, the Long-tailed Blue, and is decidedly popular with various bee species.

Deadly Nightshade (Atropa belladonna), poisonous and from the same family as potatoes and tomatoes, is much less often seen than Woody Nightshade (Solanum dulcamara). Native to the UK only on calcareous soils, it has impressive flowers (30mm) and berries (20mm).

Images © Jeremy Early. All rights reserved.

In 2013 I published My Side of the Fence - the Natural History of a Surrey Garden. Details may be found, and orders placed, via this hyperlink My Side of the Fence. In November 2015 Surrey Wildlife Trust published the atlas Soldierflies, their allies and Conopidae of Surrey, jointly written by David Baldock and me. Details are on this web page: Atlas.