Notes on Essex Specialities. 8: the fifty year history of Orobanche crenata in Essex
(in this case, a pleasant one) being emitted by the corolla and acting as an insect attractant. The best
plants develop after a really hot summer from mid-July to August, somewhat later than in the
Mediterranean region where it usually flowers from April to June.
After 1975, it appeared in the same area each year. 70 spikes in 1977 (Patrick Smith), 80-100 spikes
in August 1979 (K.J.A), peaking at 200 plants in 1981 (K.J.A), still largely associated with the Vicia
tetrasperma colony, but also present in barley stubble further to the east in the same field. Around
200 spikes also appeared in 1982, mainly on V. tetrasperma but also on Hairy Tare V. hirsuta (Fred
Rumsey). By 1983 however, the population had fallen to just a liandful of flowering spikes (Colin
Studholme et Thurrock Nat. His. Soc). Unfortunately, despite the author negotiating with the London
Borough of Havering to have the site incorporated into the newly designated (1983) Cranham Marsh
Nature Reserve, - the Essex Naturalists' Trust subsequently allowed the site to develop into a reed
bed and to scrub over with Aspen. Apart from 3 plants seen in a field of peas 1 mile to the NNE of
the site in 1986 (Mary Smith), no further sightings were reported until 1994 when Tony Gunton (the
new reserve warden) reported two spikes by the hedge east of Middle Wood. Tony had cleared the
scrub, and also established some broad bean seedlings at the original site in July of that year, which
he then dusted with seed from one of the spikes. By late July-early August several flower spikes had
appeared on the beans, probably from dormant plants already in soil, rather then the new seed,
though it is just possible that they were from the seeds dusted onto the young seedlings. It would be
interesting to repeat the experiment with host plants grown on sterile soil to see just how short the
life cycle can be.
No plants were reported in 1995 or 1996, but in 1997 all three adjoining fields were sown with peas.
Tony Gunton reported the first plants among the pea crop in July, and by the 10 August when Tim
Pyner and the author surveyed the site, by measuring out quadrats after the crop had been harvested,
the population was vast. We estimated that between 400,000 and 700,000 flowering spikes occurred
in the field just south of Middle Wood, several thousand more occurred in the field between Middle
and Bonus Woods and in the field immediately to the south of South Marsh there were around 500
further spikes, mostly fanning out into the field from the gateway into the adjoining field immediately
south of Middle Wood, obviously from seed carried through the gateway on the wind.
Following this devastating occurrence local farmers were warned not to plant legumes in the area for
several years, (as the parasite can depress crop yield in legumes by as much as 90%) and in 1998
only 3 spikes were recorded in the area, one on the verge of Pike Lane, 200 yds east of Bonus Wood,
and two in the original triangle site (Tony Gunton). In 1999 no spikes were reported, but in late July
2001. Patrick Smith spotted a dozen or so plants in a pea crop on Manor Farm just south of Ockendon
Road, some 200m due south of Bonus Wood. On being pointed out to the owner, the crop was sensibly-
ploughed in immediately, and no records have been traced from the area since then.
The story of O. crenata is unlikely to end here however, as at least some of the seed will have made
its way into the air currents and is probably waiting below ground in a wide area around Cranham for
suitable host crops to awaken it from its sleep. Neither docs the story of this mysterious plant begin
in 1975. To trace its earlier exploits we have to look into the herbaria and old botanical records.
Looking into old county Floras we find that at Charlton in 1845 and at Stroud in 1863. both in
Gloucestershire, O. caryophyllacea was supposedly recorded in a bean field and on peas respectively.
As Fred Rumsey points out (Rumsey 1986), these were probably the first U.K. records of O. crenata.
Bedstraw Broomrape O. caryophllacea, is very choosy and only parasitizes Galium and Asperula
species (Kreutz 1995). It does however have a clove/carnation scent. It turned up again in Glos, in
1905 at St. Philip's Marsh, Bristol. In 1860 it appeared on peas in a garden at Bridgewater in Somerset
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Essex Naturalist (New Series) 20 (2003)