was consequently named by Duchesne _dioica_; but it frequently produces
hermaphrodites; and Lindley,[729] by propagating such plants by
runners, at the same time destroying the males, soon raised a
self-prolific stock. The other species often show a tendency towards an
imperfect separation of the sexes, as I have noticed with plants forced
in a hot-house. Several English varieties, which in this country are
free from any such tendency, when cultivated in rich soils under the
climate of North America[730] commonly produce plants with separate
sexes. Thus a whole acre of Keen's Seedlings in the United States has
been observed to be almost sterile from the absence of male flowers;
but the more general rule is, that the male plants overrun the females.
Some members of the Cincinnati Horticultural Society, especially
appointed to investigate this subject, report that "few varieties have
the flowers perfect in both sexual organs," &c. The most successful
cultivators in Ohio, plant for every seven rows of "pistillata," or
female plants, one row of hermaphrodites, which afford pollen for both
kinds; but the hermaphrodites, owing to their expenditure in the
production of pollen, bear less fruit than the female plants.

The varieties differ in constitution. Some of our best English kinds,
such as Keen's Seedlings, are too tender for certain parts of North
America, where other English and many American varieties succeed
perfectly. That splendid fruit, the British Queen, can be cultivated
but in few places either in England or France; but this apparently
depends more on the nature of the soil than on the climate: a famous
gardener says that "no mortal could grow the British Queen at Shrubland
Park unless the whole nature of the soil was altered."[731] La
Constantina is one of the {354} hardiest kinds, and can withstand
Russian winters, but is easily burnt by the sun, so that it will not
succeed in certain soils either in England or the United States.[732]
The Filbert Pine Strawberry "requires more water than any other
variety; and if the plants once suffer from drought, they will do
little or no good afterwards."[733] Cuthill's Black Prince Strawberry
evinces a singular tendency to mildew: no less than six cases have been
recorded of this variety suffering severely, whilst other varieties
growing