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The Essex Naturalist
TL(52)54 500,432 19 Great Chesterford, flooded gravel pit by Ml 1,
frequent in the shallows, heavily encrusted,
antheridia and oogonia present. 14 July 1990. Tim
Pyner.
TL(52)62 ???????? 19 Felsted, 1952. Coll: E.A.Robinson. Confirmed: Guy
O.Allen. B.S.B.I. Proceedings. 1. p.69. 1954
TL(52)71 718,104 19 Broomfield, flooded gravel pit near Hill Farm, south
of the boating lake, abundant with antheridia and
oogonia. 14 July 1990. Tim Pyner.
3f Chara vulgaris var. contraria (A.Braun ex Kutz.)
Formerly regarded as a separate species, this taxon has been demoted to being a
variety of C. vulgaris in Moore et al (1986). The only definitive difference between
this form, and the other varieties of C. vulgaris, is that its primary spine-bearing
cortical rows are prominent and the secondary rows recessive, so that the spines
appear to arise from ridges (c.f. the other C. vulgaris varieties in which they appear to
arise from the grooves). Guy Allen in his British Stoneworts (1950), also claimed a
correlation between the inequality of the two circlets of stipulodes and primary row
dominance, and used it empirically as a means of separating pressed material of C.
vulgaris sensu stricto, from C. contraria. Moore et al (1986), however, regard the
relative prominence of the primary, as opposed to secondary rows as being a variable
character not worthy of a specific difference. This variety is also supposed to be
usually heavily encrusted, but the only two Essex specimens I have seen were not.
The var. hispidula, is close to var. contraria, in that it too, has dominant primary rows,
but it has well developed spreading spine cells, and has not so far been recorded for
Essex. The rarity of var. contraria in Essex, despite the abundance of C. vulgaris sensu
lato, and the absence of var. hispidula, suggest that either the gene(s) controlling
cortical row dominance variation are absent in this area of the country, (but
common in Central Ireland, for example), or that C. contraria is indeed worthy of
specific rank, with hispidula as its variety, and that there is variation in row
dominance within that species, ranging from no difference between the two rows, to
primary row dominance. Alternatively, perhaps, the variation may be generated by
occassional hybridization with C. vulgaris. In Essex we need to look more carefully, at
for example, what appear to be var. longibracteata plants, and see if primary row
dominance is ever being overlooked because of the more obvious long bracteoles.
Stewart & Church (1992) regard C. contraria as a "good" species.
TL(52)30 38,06 19 Nazeingbury Mead, flooded gravel pit, 1965, Eric
Saunders. Flora of Essex, p.45 1974.
TL(52)41 493,168 19 Near Tednambury Lock, Herts, (close to Essex
border), shallow recently cleared ditch, growing with
Groenlandia densa, 15 August 1980.
Coll: & det: by K.J. Adams.