of vegetation have had a vast influence on the commerce
of nations, and have been the great promoters of navigation, as may be
seen in the articles of sugar, tea, tobacco, opium, ginsing, betel,
paper, etc. As every climate has its peculiar produce our natural wants
bring on a mutual intercourse; so that by means of trade each distinct
part is supplied with the growth of every latitude. But, without the
knowledge of plants and their culture, we must have been content with our
hips and haws, without enjoying the delicate fruits of India and the
salutiferous drugs of Peru.

Instead of examining the minute distinctions of every various species of
each obscure genus, the botanist should endeavour to make himself
acquainted with those that are useful. You shall see a man readily
ascertain every herb of the field, yet hardly know wheat from barley, or
at least one sort of wheat or barley from another.

But of all sorts of vegetation the grasses seem to be most neglected;
neither the farmer nor the grazier seem to distinguish the annual from
the perennial, the hardy from the tender, nor the succulent and nutritive
from the dry and juiceless.

The study of grasses would be of great consequence to a northerly and
grazing kingdom. The botanist that could improve the sward of the
district where he lived would be a useful member of society: to raise a
thick turf on a naked soil would be worth volumes of systematic
knowledge; and he would be the best commonwealth's man that could
occasion the growth of "two blades of grass where one alone was seen
before."

I am, etc.

LETTER XLI.

SELBORNE, _July_ 3_rd_, 1778.

Dear Sir,--In a district so diversified with such a variety of hill and
dale, aspects, and soils, it is no wonder that great choice of plants
should be found. Chalks, clays, sands, sheep-walks and downs, bogs,
heaths, woodlands, and champaign fields, cannot but furnish an ample
Flora. The deep rocky lanes abound with _filices_, and the pastures and
moist woods with _fungi_. If in any branch of botany we may seem to be
wanting, it must be in the large aquatic plants, which are not to be
expected on a spot far removed from rivers, and lying up amidst the hill
country at the spring heads. To enumerate all the plants that have been
discovered within our limits would be a needless work; but a short list
of the more rare, and the spots where they are to be found, may be
neither unacceptable nor unentertainin