160 THE ESSEX NATURALIST.
Much interest, however, may be found in these often abused
surburban conifers when we get to know more about them and
can picture them, at least in imagination, in their native haunts.
I have made a list of those I have seen in the gardens of Leyton-
stone, Wanstead, Woodford, and Chingford, as far as I could
make them out from the road, and find they number twenty-
seven species. Probably this list is far from complete, and I
should be grateful to anyone who would help me to add to it.
Considering that conifers demand pure air, if they are to thrive,
I think our district has not done badly.
But it may well be asked "what is a conifer?"
Conifers belong to the division of seed-bearing plants, called
Gymnosperms (from the Greek gymnos naked, sperma seed) or
plants with naked ovules, as contrasted with the true flowering
plants or Angiosperms (Greek aggios a little box, sperma seed),
in which the ovules are in a closed box, or ovary, the result being
that in Gymnosperms the pollen grains are carried by the wind
direct to the ovules, and in Angiosperms they can only reach
the ovules by penetrating the stigma of the ovary.
Gymnosperms have an extremely ancient ancestry, dating
back as far as the Carboniferous formation.
Modern Gymnosperms are divided into four great classes:—
Cycads, Gnetales, Ginkgoales and Conifers.
The Cycads, which in a past geological period formed one
of the most important groups of plants on the land surface of
the earth, are now reduced to a few genera and species growing
chiefly in the southern hemisphere. They are mostly short,
stout-stemmed plants, with very large fern-like leaves, and with
large terminal cones of either male or female flowers. None of
them are capable of growing out of doors in English gardens,
and so, although from the point of view of relationship they
are extremely interesting, we need not refer to them further
here.
The Gnetales are a still smaller group of curious plants, con-
taining three genera, which differ much in appearance from each
other and from other Gymnosperms; in some respects they
show affinities with true flowering plants.
The Ginkgoales contain a single genus and species, Ginkgo
biloba, the Maidenhair tree. Until recently the tree was
regarded as a conifer, and this is my excuse for speaking of it