7
There are said to be three distinct forms of A. castellana:
var. aristata - awns present on all lemmas, lateral nerves of lemmas
prominent and excurrent at tip.
var. neuta - No awns OR excurrent nerve.
var. mixta - awned and awnless spikelets in the same panicle, usually
only the spikelets of the final branchlets have awns.
ANISANTHA
The alien Great Brome A. diandra and the Ripgut Grass, A. rigida are dubiously distinct and
should perhaps only be allotted varietal status, as morphological characters intergrade. The
former is soft and pendent and the latter stiff and erect. Most if not all our south Essex material
would appear to be A. diandra.
BROMUS
Two other grasses with morphological overlap, that are doubtfully distinct according to Tom
Cope, are Bromus commutatus and Bromus racemosus. B. commutatus is supposed to be a
good ancient grassland indicator, but a veiy different form occurs as a robust and abundant
arable weed, also occurring on waste ground. To separate B. racemosus and B. commutatus
Tom Cope recommends scoring all five of the following characters:
racemosus commutatus
Spikelet length 10-16mm 15-28mm
Length of lowest rachilla joint 0.7-1.0mm 1.3-1.7mm
Length of lemma 6.5-8.0mm 8.0-11.0mm
Lemma margin rounded angled
Anther length 1.5-3.0mm 1.0-1.5mm
It would be useful to record the habitat (old grassland/arable-waste ground) for B. commutatus
in case the two forms turn out eventually to be different.
Ken Adams
Essex Field Club Newsletter No. 19, November 1996