The Essex Naturalist
7
Tilbury Fort, but only discovered in abundance just east of the Power Station in
1992. Water Violet Hottonia palustris and Great Water Dock Rumex
hydrolapathum grow in the drainage ditches of Tilbury Marsh but no-one seems
to have noticed them until very recently. The discovery of Opposite-leaved
Pondweed Groenlandia densa by a team from the Nature Conservancy Council in
1987 is most exciting, but needs to be confirmed. This species was described as
extinct in Jermyn. It certainly seems that the Marsh contains both fresh and
brackish water and the NCC survey turned up several nationally scarce
invertebrates. Another very scarce plant with only a very few south-eastern
localities is the Autumn Squill Scilla autumnalis. This has been known from
nearby Orsett Golf Course for many years (Jermyn 1974), but was not
discovered growing on Broom Hill until 1991.
As far as invertebrates go, these were, until very recently, almost a completely
unknown quantity. Now we know that this is, without doubt, one of the richest
areas in the county for several groups.
Some Tilbury sites
Hall Hill
I first visited Hall Hill close to West Tilbury Hall, in 1981 with John Skinner
when we found Subterranean Clover Trifolium subterraneum and Annual Knawel
Scleranthus annua. Later surveys revealed Lesser Calamint Calamintha nepeta in
quantity as well as Sandwort Arenaria serpyllifolia and Wall Pepper Sedum acre.
An old pond near the hill's summit has Divided Sedge Carex divisa and Parsley
Water Dropwort Oenanthe lachenalii. This attracts two water-loving hoverflies,
Anasimyia lineata and Parhelophilus frutetorum. Several scarce insects have been
seen on the hill including Andrena florea a solitary bee dependant on White
Bryony Bryonia dioica flowers and Psithyrus rupestris, a large red-tailed cuckoo
bee.
Broom Hill
On the 27th August 1991 I had cycled to Tilbury Marshes and for some
unknown reason decided to turn into the dead-end lane called Biggin Lane near
Chadwell St Mary. This narrow lane passes a row of cottages which is the
hamlet of Biggin. The road came to an end, but continued as a track over the
brow of Broom Hill (called Gun Hill on some OS maps). Gazing up at its horse-
grazed slopes studded with Broom, I knew I had found something worth
exploring. It looked to me like ancient pasture and I was not disappointed. At
the summit were huge patches of Autumn Squill Scilla autumnalis, the very plant
Tim Pyner and I had searched for (unsuccessfully) at Orsett the year before. This
plant has only two or three localities in the whole of south-east England. Future
visits confirmed a rich flora and later, work by Peter Harvey began to reveal the
extraordinary richness of the invertebrate fauna. The quarry at the summit
which had been excavated in the 1960s seemed to be especially good for