On the Species of the Genus Primula in Essex. 209
together, but never where only one grows.66 Darwin suggests
that its frequency in some places may be due to a particular
species of moth or other insect which visits both plants, but,
until we know more certainly what insects visit either species,
this point must remain unsettled. The period at which these
Hybrid Oxlips flower is probably very largely regulated by
the parent the hybrid most takes after, but I was surprised
to see one partaking strongly of the Cowslip nature out as
early as March 7th last. They not unfrequently remain in
flower until quite the end of May, when all other Primulas
are over. This I suppose to be due to their want of fertili-
zation, as many flowers remain out for a long period when
fertilization is prevented ; but these hybrids, as usual, are to
a large extent sterile, and therefore cannot be fertilized.
The Hybrid Oxlip is, on account of the absence of the
Primrose, but very little mixed with P. elatior in the district
inhabited by the latter, except just on the extreme edge of its
area. It is rather strange that in several woods in the
neighbourhood of Saffron Walden all the forms (Cowslip,
Oxlip, Primrose, Hybrid-elatior, and Hybrid Oxlip) should
grow. This, the late Mr. Gibson informed me, is the case in
Quendon Wood. I have already spoken of Westley Wood
and Grim's Ditch Wood, on opposite sides of the Slade
Valley. In the former I have for three years running found
all the forms, and this year (1883) also in the latter. Prim-
roses abound in Westley Wood, and in several places
Cowslips extend a little way up the paths, and as a con-
sequence there are a few plants of the Hybrid Oxlip, while
on the edge nearest to Grim's Ditch Wood are a few plants of
56 The Hybrid Oxlip is said, on good authority, never to be found on
the Continent, where the Primrose and the Cowslip do not grow inter-
mixed as with us. Nevertheless there is at Kew a specimen labelled
"P. officinali-vulgaris, Pres Montreux, Vaud, 15-4-75, F.," which seems
to be identical with the Essex plant of the same name. Many other
specimens which appear to me to be hybrids with elatior are arranged
with English Hybrid Oxlips (P. veri-vulgaris) under the name of "P.
variabilis, Goup." One such is labelled "Hotel Byron, nr. Chillon,
Avril, '51. Cette plante hybride de la P. acaulis et de la P. officinalis
n'est pas rare dans les environs de Montreux, G. M."