Source: Penfold, F. “Marrubium in Arundel Park.” Sussex Botanical Recording Society Newsletter, no. 51 (Jan 2001). http://sussexflora.org.uk/wp-content/uploads/2016/03/Newsletter_Jan_2001.pdf.
White Horehound is again flourishing at this site, over 150 plants having been recorded by Frances Abraham and me in April 2000. The population starts about 25m from where I last recorded it in 1972 at TQ016083, and continues W and NW in a band just below the fencing of Box Copse, through the station at TQ011085 found by David Bangs in 1999 and reaching as far as his record for TQ011087. It is regarded as native in S. England, but the Sussex Plant Atlas gives only two sites in VC13 during the period 1966-78, one of which was Arundel Parl; it was subsequently found at Halnaker, most recently by Howard Matcham in the chalk pit. Wolley-Dod recorded it in 1937 as plentiful in the valleys N of Swanbourne Lake in Arundel Park. My own Arundel records started in 1953 and ended in 1972, shortly after which it was destroyed at that site by cattle erosion; my first record for Halnaker is 1991.
This plant has been used as a herbal remedy in Europe for at least 2000 years and was cultivated in this country. The location in South Stoke parish was created by the Duke of Norfolk as a deer-park in the early 19th century, having previously been a rabbit warren of the Dale Park Estate. In the 1950’s the Red and Fallow Deer were removed and replaced by cattle, which watered in Swanbourne Lake. Myxomatosis destroyed the rabbits from 1954, resulting in heavy scrub infestation, especially Hawthorn. The Beech hangers had been falling from senescence and the great storms of 1987-90 completed the process. The Arundel Estate therefore started a programme of replanting and fencing, taking care to leave as much of Box Copse as possible. A piped water supply was installed and the cattle replaced by sheep.
An intriguing historical note relates to the name Arundel, which some authorities like to derive from the Old English ‘har-hun dell’, the valley of the horehound. Others favour the easier ‘Dell of the Arun’, but history is not on their side, as the river did not acquire that name before the 16th century, having previously been known as Tarente (Tarrant) in Roman and Saxon times, followed by Hault Rey and Alta Ripa (Norman), the River of Arundel (13th century) and the High Stream in Arundel Rape as late as 1636. In Domesday Book we have Harundel in 1086. I was inclined to scorn this derivation from the supposed prevalence of the plant, but seeing a vast area of country near Adelaide (Australia) thickly covered by Marrubium vulgare (White Horehound), probably introduced from Europe, made me wonder how abundant this plant may have been in this area 1500 years ago.