perhaps the tetraploid ones cannot hybridise with ordinary Primroses. So no hybrids
would have arisen until a substantial number of the Cowslips were tire usual diploid.
Can anyone out there who knows about plant genetics let me know if this theory is
reasonable or not?
You will no doubt be thinking by now that our native Oxlips should get a mention, since
they only grow in Britain around the western end of the Essex/Suffolk border. They are
different in several details from the False Oxlips. They are a separate species in their
own right, although they can, and do, hybridise with Primroses growing nearby. Unlike
the polyanthas, these hybrids are fertile and back-cross repeatedly. We have also seen
Oxlips abundant on high meadow slopes (above 1,800m, near the snow-line in early
June) in the Pyrenees, on the French/Spanish border. But in the mountains the Oxlips
and Primroses very rarely hybridise as they are separated vertically by almost 1,000m;
the Oxlips grow only on the high meadows and the Primroses only in the wooded valleys.
In Britain, both grow in lowland woods. Both of the Oxlip areas have basic or lime-rich
soils, but there the similarities of habitat end.
St Mark's Flies were abundant today, 5th May, even though St Mark's Day is 25th April.
A group of us were in Duck Wood, part of the new Manor Nature Reserve in the north of
Havering, and we took a picnic out into the grassy sports field just behind the wood. We
were soon moving around trying to escape these large, black, flying insects with their
long black legs hanging down. I don't remember ever having seen them before, but one
of our number knew what they were. There must have been thousands of them, all in the
air up to about 2m above the grass. Luckily they did not bite us, or land on our food, but
they certainly landed on our clothing. Suddenly the sun disappeared from view and a
slightly chill breeze got up. Within minutes, the air was almost clear again, but we saw
lots of them crawling about in the grass, many paired in copulation. Having contacted
our County Recorder for flies, Del Smith, I have learned that these insects are actually
quite common, but you need exactly the right weather conditions at the right time of
year to see so many at once.
St. George's Day is 23rd April, and St. George's Mushrooms are so called because they
appear at about this time. On the same day as we saw the St Mark's Flies above, in a
grassy verge by Duck Wood we found a group of nearly a dozen fresh mushrooms, and
these enhanced our supper considerably. They smell strongly of new meal, and they
look lovely with their creamy coloured caps, stem and gills, and the caps are quite thick
so you can actually get a worthwhile mouthful or three from them (see plate 2).
Then a few days later on 10"' May another insect horde took our attention for some
minutes; this time it was the Brown-tailed Moth larvae on a Spindle tree, and it was the
web covering over the groups of eggs/larvae that first caught our eyes from some distance
away. On closer examination, there were many thousands of tiny larvae crawling over
the whole tree to such an extent that all the green leaves had been devoured. Other
shrubs in the same hedge such as Hawthorn and Blackthorn were quite untouched. Again,
6 Essex Field Club Newsletter No. 48, September 2005