ESSEX   BOTANY   AND   MYCOLOGY  GROUPS 

Following the introductory paragraph to each taxon, the records are set out in columns. The first being the letter and alternative number (in brackets) code for the 100 x 100km square, followed by the 10 x 10km square number, arranged in conventional order from south to north, moving from west to east; the second column gives the 1 x 1km square or the 100 x 100m square Ordnance Survey grid reference if known; the third the vice county, and the final column the available details of the individual record. Approximate grid references for older records are suffixed by a?

TQ(51) 39

??????

18

Chingford, (as N. opaca), 3 May 1884. H.G.Slatpole.

Natural History Museum Herbarium (BM). Atlas Specimen No.1779.

Chingford, pond (as N. opaca), 3 May 1884. Coll: J T Powell.

Passmore Edwards Museum Herbarium (SRD).

TQ(51) 49 or  TL(52)40

??????

18/19

Epping Forest, (as N. opaca), vague record, c.1850. Edward Forster

Natural History Museum Herbarium (BM). Atlas Specimen No.1780.

TQ(51)49

429,981

18

Goldings Hill Pond, (as N. opaca), 1965. Coll: & det: Eric Saunders.

Flora of Essexp.45.1974.

TQ(51)59

58 ,99

18

Doddinghurst, (as N. opaca), nearBrentwood, old pond near Doddinghurst Farm, with C. vulgaris and C. globularis (as C. fragilis), Sept. 1894. Coll: by William Allen, specimen checked Arthur Bennett.

Essex Naturalist. 10. p.190. 1897-98.

TQ(51)69

638,952

18

Hutton, (as N. opaca), abundant in the Stud Pond, 10 Aug. 1960. Coll: Stanley T.Jermyn, det:? Eric Saunders

Flora of Essex. p.45. 1974. Also Natural History Museum Herbarium (BM). Atlas Specimen No.1781.

TL(52)81

???????

19

Two specimens in Natural History Museum Herbarium (BM). Atlas Specimen No. 1782

TM(62)12

154,215

19

.Weeley, scattered plants in deep shade, west side of pond surrounded by trees, beside Weeley Church. The only macrophyte present Ceratophyllum demersum. Immature antheridia only, and apices typically blunt, (i.e. `N. opaca'). 26 May 1986.(No oogonia when plant grown on) Coll: & det: K.J.Adams

TM(62)02

004,238

19

Colchester, Bourne Mill Pond, first recorded in October 2002, still present June2003 and material cultured to October 2003 (still no gametangia). Peter and Pamela Wilson. KJA collected large quantities from the pond in November 2002 but no sign of gametangia. However, on 12 May 2004, KJA collected material from several places along the road bank and all of it had immature antheridia, even the young shoots had minute green antheridia in the axils of the dactyls. The material collected by Peter and Pam in October 2002 and cultured in a container in their garden also produced antheridia in May 2004.This material is thus clearly dioecious, and the entire Bourne Pond population is probably male, and therefore

N. opaca s.s. As these antheridia were immature in May, [whereas those of N. flexilis would be going over by this date] it may be that N. opaca antheridia mature much later than those of the former. We need to see more material over several years and to find female clones of N. opaca. Unfortunately, minute Limnaea snails, the same size as the antheridia, devoured them all before they had a chance to mature in KJA's cultures! The Wilson's had better luck and antheridia on their plants persisted until at least 1 August in 2004.