THE ORDER ROSACEÆ, ILLUSTRATED BY DIFFERENT KINDS OF ROSES; THE
POTENTILLA; THE STRAWBERRY; THE RASPBERRY; SPIRÆA; KERRIA OR
CORCHORUS JAPONICA; THE ALMOND; THE PEACH AND NECTARINE; THE APRICOT;
THE PLUM; THE CHERRY; THE APPLE; THE PEAR; THE MOUNTAIN ASH; THE
WHITE BEAM TREE; QUINCE; PYRUS OR CYDONIA JAPONICA; THE HAWTHORN;
THE INDIAN HAWTHORN; THE MEDLAR; PHOTINIA; ERIOBOTRYA; COTONEASTER;
AMELANCHIER; BURNET; AND ALCHEMILLA OR LADIES’-MANTLE.
All the numerous plants which compose this large order agree more or
less with the rose in the construction of their flowers, though they
differ widely in the appearance of their fruit. They all agree in
having the receptacle dilated, so as to form a lining to the lower part
of the calyx, and in the upper part of this lining the stamens and
petals are inserted above the ovary; and the anthers are innate, that
is, the filament is inserted only in the lower part. The leaves also
have generally large and conspicuous stipules; and they are frequently
compound, that is, composed of several pairs of leaflets, placed
exactly opposite to each other; though the leaves themselves are never
opposite to each other, but are placed alternately on the main stem.
These characters are common to the order; but the plants included in
it differ from each other so much in other respects, that it has been
found necessary to redivide Rosaceæ into tribes, of which the following
six contain plants common in British gardens.
TRIBE I.—ROSEÆ.
[Illustration: FIG. 20.—ROSA FOSTERI.]
[Illustration: FIG. 21.—OVARY OF THE AYRSHIRE ROSE WITH A DETACHED
SEED.]
[Illustration: FIG. 22.—RIPE FRUIT AND DETACHED SEED OF A ROSE.]
The flowers of the wild Rose have the lower part of the calyx tubular
and fleshy (from being lined with the dilated receptacle) and the upper
part divided into five leafy sepals, which enfold the bud, and remain
on after the expansion of the corolla. In _Rosa Fosteri_, (see _fig._
20,) and its near ally the Dog rose (_R. canina_), the sepals (_a_)
do not extend far beyond the petals of the bud; but in some species,
as in _Rosa cinnamonea_ and its allies, the sepals are so large and
long, that they assume the character of little leaves, The corolla is
cup-shaped, and it is composed of five equal petals, each of which is
more or less indented in the margin, as shown at _b_. In the centre
of the flower the receptacle forms a kind of disk which completely
fills the opening or throat of the calyx; in most species covering the
carpels and their styles and only leaving the stigmas free, though
in the Ayrshire rose (_R. arvensis_), and its allies, the styles are
united, so as to form a column, which projects considerably above the
disk (see _fig._ 21). The pitcher-shaped part of the calyx when the
corolla falls becomes the hip (_fig._ 20 _c_), and serves as a covering
or false pericarp to the numerous bony carpels or nuts which contain
the seed. These nuts are each enveloped in a hairy cover (see _fig._ 20
_d_, and _fig._ 21 _a_,) and each contains only one seed which it does
not open naturally to discharge: hence, the seeds of roses when sown
are a long time before they come up. _Fig._ 22 is the ripe fruit of
_Rosa cinnamonea_, cut in two to show the nuts. The leaves are pinnate,
consisting of two or more pairs of leaflets, and ending with an odd
one. The leaves are furnished with very large stipules (see _fig._ 20
_e_); and the stems have numerous prickles (_f_), which differ from
thorns in being articulated, that is, they may be taken off without
tearing the bark of the stem on which they grow, only leaving the scar
or mark, shown at _g_. The leaves of the sweet briar are full of small
glands or cells filled with fragrant oil, which may be distinctly seen
in the shape of little white dots, when held up to the light; and this
is the reason of their delightful perfume. When the leaf is rubbed
between the fingers, the thin skin that covers the cells is broken, and
the oil being permitted to escape, the fragrance is increased. There
are only two genera in this tribe, viz. _Rosa_ and _Lowea_, the latter
containing only what was formerly called _Rosa berberifolia_, and which
has been thought worthy of being made into a separate genus principally
on account of its having simple leaves without stipules, and branched
prickles.
TRIBE II.—POTENTILLEÆ OR DRYADEÆ.
The plants belonging to this tribe agree more or less in the
construction of their flowers with the well-known showy plants called
Potentilla, but my readers will probably be surprised to hear that the
raspberry and the strawberry are included among them. If, however,
they compare the flower of the Potentilla with that of the strawberry,
they will find them very much alike. In both there is a calyx of ten
sepals, and a cup-shaped corolla of five petals; and in both the
stamens form a ring round an elevated receptacle, on which are placed
numerous carpels. Here, however, the resemblance ceases, for as the
seeds of Potentilla ripen, the receptacle withers up in proportion to
the swelling of the carpels, till it becomes hidden by them; while in
the strawberry the receptacle becomes gradually more and more dilated,
swelling out and separating the bony carpels still farther and farther
from each other, till at last it forms what we call the ripe fruit.
I have already had several times occasion to mention the receptacle,
which though seldom seen, or at least noticed, by persons who are not
botanists, is a most important part of the flower, and one that assumes
a greater variety of form than any other. Sometimes, as we have seen
in several of the Ranunculaceæ and Leguminosæ, it is a mere disk or
flat substance serving as a foundation to hold together the other
parts of the flower; and at other times we have found it drawn out
into a thin membrane and divided into a kind of leaves, as it is among
the carpels of the tree-peony; but in no plants that I have yet had
occasion to describe does it assume such strange forms as in Rosaceæ.
The flower of the strawberry (_Fragaria vesca_) has a green calyx of
ten sepals; five of which are much smaller than the others, and grow
a little behind them, the large and small ones occurring alternately.
The corolla is cup-shaped, and in five equal petals; the stamens are
numerous and arranged in a crowded ring round the carpels, which are
placed on a somewhat raised receptacle. The carpels or nuts resemble
those of the rose, but they have no hairy covering, and indeed look
hard and shining on the surface of the distended receptacle, or
polyphore as it is called in its metamorphosed state. The carpels
when ripe do not open to discharge the seed, and consequently as they
are sown with the seeds, the young plants are a long time before they
appear. The strawberry has what is called ternate leaves, that is,
leaves consisting of three leaflets; with large membranous stipules.
The calyx is persistent, that is, it remains on till the fruit is ripe.
[Illustration: FIG. 23.—FLOWERS AND FRUIT OF THE RASPBERRY.]
The Raspberry (_Rubus Idæus_) differs widely from the strawberry in
many particulars, notwithstanding their being included not only in the
same natural order, but in the same tribe. The calyx has only five
sepals (_a_ in _figure_ 23); and though the corolla has five petals
(_b_), they do not form a cup-shaped flower. In the centre are the
carpels, the form of which is shown of the natural size at _c_, and
magnified at _d_, the latter showing that each has a separate style and
stigma. As the raspberry advances, the petals drop, and the receptacle
becomes elevated into what is called a torus, as shown of the natural
size at _e_; bearing the carpels upon it, which gradually swell out and
soften, till each becomes a little pulpy fruit, full of juice, and
having the stone or seed in the centre. While this change is taking
place, the stamens gradually wither and fall off, and the stigmas
disappear, the style shrivelling up to the appearance of a hair; the
pulpy carpels have also become so pressed against each other, as to
adhere together, and the whole, with the persistent calyx, now assumes
the appearance shown at _f_. As soon as the carpels become ripe they
cease to adhere to the torus, and they may be pulled off and eaten
(the torus, or core as it is called, being thrown away): each carpel
will be found to inclose a very hard seed or stone, as shown at _g_.
If the Raspberry, instead of being gathered, be suffered to remain on
the stalk, the juicy carpels dry up, and fall with the seed inclosed.
The stems of the Raspberry are biennial, that is, they do not bear
till they are two years old, after which they die; but the roots are
perennial, and they are always sending up fresh suckers, so that the
same plants will bear for many years in succession, though not on the
same stems. The stems are generally erect, and prickly like the rose;
and the leaves on the bearing stems have three leaflets, while those on
the barren stems have five; and in both cases the leaflets are covered
with white down on the under side. All the different kinds of Bramble,
such as the Dewberry, Blackberry, &c., agree with the Raspberry in
the construction of their fruit, though they differ in the number of
their leaflets, the size and colour of their flowers, and other minor
particulars.
Several other genera belong to this tribe, among which may be mentioned
_Geum Avens_, or _Herb Bennet_, the carpels of which have each a
hooked style; _Sieversia_ separated from Geum, because the carpels end
in a straight feathery awn; and _Tormentilla_, the flowers of which
bear a general resemblance to those of Potentilla, but which have an
eight-parted calyx; a corolla of four petals; sixteen stamens, and dry
wrinkled carpels on a depressed receptacle. All these genera my readers
will find it interesting to procure flowers of, in order to compare
them with each other. This and the preceding tribe are considered by
some modern botanists to form the order Rosaceæ; the other tribes being
formed into separate orders.
TRIBE III.—SPIRÆEÆ.
The only genera in this tribe which contain well-known plants are
Spiræa and Kerria. In Spiræa the calyx is five-cleft (see _a_ in
_fig._ 24) and lined with the dilated receptacle, forming a shallow
tube or rather cup for the reception of the carpels. There are five
small roundish petals (_b_), and from twenty to fifty stamens (_c_),
which project very far beyond them. In the centre are from two to five
carpels (_d_), which are something like those of the raspberry when
young, but afterwards become of the kind called follicles; each carpel
contains from two to six seeds affixed to its inner suture, and they
are dehiscent—that is, they open naturally at the top to discharge the
seed (see _e_). The flowers are set very close together, and from this
circumstance, combined with their small size and projecting stamens,
they look like fine filigree work; hence the popular English names
given to _S. salicifolia_ or Bridewort, Queen’s needle-work, &c. The
flowers of this species are in spicate racemes, but others are in
corymbs, as in _S. bella_; or in panicles, as in _S. ariæfolia_.
[Illustration: FIG. 24.—FLOWER OF THE SPIRÆA.]
Kerria is a genus containing only one species, the plant which was
formerly called _Corchorus japonica_; the calyx is united at the base,
but divided in the upper part into five lobes; three of them obtuse,
and the other two tipped with a little point called a mucro. There
are about twenty stamens about the same length as the petals arising
from the calyx, and five roundish carpels containing one seed each.
The leaves are simple, and the stipules awl-shaped. Till lately only
a double-flowered variety was known in Britain; but about 1832, the
single-flowered plant was introduced from China. Corchorus, the genus
in which this plant was originally placed, is nearly allied to the
lime-tree.
TRIBE IV.—AMYGDALEÆ.
This tribe is distinguished by the fruit, which is what botanists call
a drupe, that is, a stone fruit. The principal genera included in this
tribe are _Amygdalus_, the Almond; _Persica_, the Peach and Nectarine;
_Armeniaca_, the Apricot; _Prunus_, the Plum; and _Cerasus_, the
Cherry. All these genera contain more or less of prussic acid, which
is found to exist principally in the leaves and kernels; and they all
yield gum when wounded.
The flowers of the common Almond (_Amygdalus communis_) appear, as is
well known, before the leaves, bursting from large scaly buds, which
when they open throw off the brown shining bracts in which they had
been enwrapped. The calyx is somewhat campanulate, with the upper part
cut into five teeth or lobes, and it is lined by the dilated disk.
There are five petals, and about twenty stamens, both inserted in the
lining of the calyx. The anthers are innate, and they differ from most
of the other plants yet described in being only one-celled. The ovary
is also only one-celled, and there are generally two ovules, though
the plant rarely ripens more than one seed. The leaves are simple, and
they have very small stipules. When the petals drop, the ovary appears
covered with a thick tough downy pericarp, within which is the hard
stone or nut, the kernel or almond of which is the seed.
The Peach (_Persica vulgaris_) was formerly included in the same genus
as the almond; and in fact there is but little botanical difference.
The flowers are the same both in construction and appearance; and the
leaves are simple like those of the almond, and, like them, they are
conduplicate (that is, folded together at the midrib) when young. The
only difference indeed is in the fruit; for, as everybody knows, the
stone of the peach has not a dry tough covering, like that of the
almond, but a soft and melting one full of juice, and the stone itself
is of a harder consistence, and deeply furrowed, instead of being only
slightly pitted. The fruit of the peach has thus a fleshy pericarp, the
pulp or sarcocarp of which is eatable, and a furrowed nut or stone,
inclosing the seed or kernel, which is wrapped up like that of the
almond, in a thick loose skin.
The Nectarine (_P. lævis_) only differs from the peach in the epicarp,
or outer covering of the pulpy part, being smooth instead of downy.
Of both fruits there are two kinds, one called free-stone, from their
parting freely with the stone; and the other cling-stone, from the
stone clinging to the fibres of the pulp.
The Apricot (_Armeniaca vulgaris_) agrees with the preceding genus in
its flowers; but it differs in its fruit, its stone being sharp at one
end and blunt at the other, with a furrow on each side, but the rest of
the surface smooth. Thus my readers will perceive that the Peach and
the Apricot, though so different from each other as to be recognised
at a glance, are yet botanically so very closely allied, as to be
distinguished only by the stone. The leaves indeed differ in form, but
in other respects they are exactly the same.
The Sloe (_Prunus spinosa_) is supposed by some botanists to be the
origin of our cultivated plum, though others make it a separate species
under the name of _Prunus domestica_. The flowers in both are solitary
(see _fig._ 25), and consist of a five-toothed calyx (_a_) which
is united at the base, and in the lining of which the stamens are
inserted as shown at (_b_). The ovary has a thick style and capitate
stigma (_c_), and the fruit is a drupe (_d_). In these particulars
therefore the plum agrees with the preceding genera; but it will be
found to differ in the skin of the pericarp, which is quite smooth and
covered with a fine bloom; this, indeed, and its stone being pointed
at both ends constitute the chief botanical distinctions between the
fruit of the plum and that of the apricot, as in other respects they
are alike. Both the plum and the apricot have footstalks, and in this
differ from the peach and the nectarine, which are without. The leaves
of the plum differ from those of the other genera in being convolute,
that is, rolled up, in the bud.
[Illustration: FIG. 25.—FLOWERS AND FRUIT OF THE SLOE.]
The Cherry (_Cerasus vulgaris_) differs from the plum in the skin of
the pericarp being destitute of bloom, and in several flowers springing
from each bud, in what botanists call a fascicled umbel (see _a_) in
_fig. 26_. The pedicels (_b_) are also much longer; the petals (_c_)
are indented in the margin; the style (_d_) is more slender; and the
stone (_e_) is smooth and much more globose. The number of the stamens,
and the manner in which they are inserted in the lining of the calyx,
is the same in both genera (see _f_); but the leaves are different, for
those of the Cherry are folded down the middle, when young, like those
of the peach and almond; while those of the plum are rolled up.
[Illustration: FIG. 26.—FLOWERS AND STONE OF THE CHERRY.]
The genus Cerasus is divided into two sections, the first containing
those species which have their flowers in bunches, and on long
footstalks, as in the common Cherry; and the second those which have
their flowers in racemes on short footstalks, as in the Bird-cherry
(_Cerasus Padus_); the Mahaleb, or Bois de Sainte Lucie (_Cerasus
Mahaleb_); the common Laurel (_Cerasus Lauro-Cerasus_); and the
Portugal Laurel (_Cerasus lusitanicus_). These plants are so different
from the common Cherry both in flowers and fruit, as far as can be
judged from their general appearance, as scarcely to be recognised;
but when closely examined their botanical construction will be found
the same. Formerly only two genera were included in this tribe—viz.
Amygdalus, which comprised the Peach and Nectarine as well as the
Almond; and Prunus, which included the Apricot and the Cherry.
TRIBE V.—POMEÆ.
The common apple (_Pyrus Malus_) may be considered the type of
this tribe, which comprehends not only what we are accustomed to
call kerneled fruit, but also the Hawthorn, Cotoneaster, and other
ornamental shrubs and low trees. The flower of the apple bears
considerable resemblance to the flowers of the genera already
described, but the petals (see _a_ in fig. 27) are oblong, rather than
roundish.
[Illustration: FIG. 27.—FRUIT AND PART OF THE FLOWER OF THE APPLE.]
The calyx (_b_) is tubular in the lower part, and the limb is divided
into five lobes. The receptacle lines the lower part of the calyx,
and forms a disk, filling its throat, in which the stamens and petals
are inserted. There are five ovaries, the styles of which are for
half their length united, leaving the upper part and the stigmas
free; and the ovaries themselves, now become cells, are enclosed in a
cartilaginous endocarp, which forms what we call the core of the Apple,
and which adheres firmly to the tubular part of the calyx. There are
two ovules in each cell, placed side by side, but generally only one
seed in each becomes perfectly ripe. As the seeds advance, the fleshy
tube of the calyx swells out and becomes what we call the apple; while
the leafy part or lobes of the limb remain on, and form the eye. Fruit
of this kind are called pomes.
[Illustration: FIG. 28.—FRUIT AND PART OF THE FLOWER OF THE PEAR.]
The Pear (_Pyrus communis_) differs from the apple in the shape of
the fruit (see _a_ in _fig_. 28), which tapers towards the footstalk,
instead of being umbilicate, that is, indented at the point of the
insertion of the footstalk, as is the case with the Apple. The
construction of the flowers in both species is the same, except that
the styles are quite free for their whole length in the Pear, and not
partially united into a column as in the Apple. This distinction,
and some others, have been thought, by some botanists, sufficient to
constitute the Apple and its allied species into a separate genus under
the name of _Malus_. The leaves of the Pear differ from those of the
Apple in being the same colour on both surfaces, whereas those of the
Apple are covered with a white down on the under side.
Besides the Apple and the Pear, and their respective allies, which form
two distinct sections of the genus Pyrus, that genus, being a very
extensive one, is divided into several other sections, all the plants
contained in which may be arranged under two heads: viz., those that
formerly constituted the genus Sorbus; and those that were once called
Aronia.
[Illustration: FIG. 29.—FLOWER AND FRUIT OF THE MOUNTAIN ASH.]
The Mountain Ash (_Pyrus aucuparia_) may be considered as a fair
specimen of most of the trees belonging to the Sorbus division. By the
details of the flowers of this species given in _fig._ 29, it will be
seen that the petals (_a_) are very small and concave; and the calyx
(_b_) is tubular, and five-cleft. There are three styles, as shown
at _c_; and the stamens (_d_), which project far beyond the petals,
are inserted in the disk. The fruit (_e_) is a pome with three seeds
(_f_) enclosed in a cartilaginous membrane, like the core of the apple
or pear. The leaves of the Mountain Ash are impari-pinnate, that is,
they consist of several pairs of leaflets, terminating in an odd one;
and the flowers are produced in corymbs. The White Beam-tree (_Pyrus
Aria_), the wild Service (_P. torminalis_), and several similar trees,
belong to this division and have the same kind of fruit as the Mountain
Ash. The true Service, however, differs in its fruit being generally
shaped like a pear, though there is a variety with apple-shaped fruit.
One species (_P. pinnatifida_) has the leaves lobed to the midrib,
instead of being cut into leaflets; and this gives the name to the
species, leaves of this description being called pinnatifid. The leaves
of the genus Pyrus often have their petioles dilated and somewhat
stem-clasping at the base; but they have generally only small stipules.
Among the other plants included in the genus Pyrus, may be mentioned
the beautiful shrub now called _Pyrus arbutifolia_, which has been
successively included in the genera Cratægus, Aronia, and Mespilus;
and _P. Chamæmespilus_, which has been successively called Cratægus,
Mespilus, and Sorbus. There are several beautiful low shrubs belonging
to this division of the genus Pyrus.
The genus Cydonia, the Quince, differs from Pyrus in having its seeds
arranged in longitudinal rows, instead of being placed side by side.
In the Chinese Quince there are thirty seeds in each row, arranged
lengthways of the fruit. The ovary of this genus consists of five
cells, each containing one row of seeds, the seeds being covered with a
kind of mucilaginous pulp. The well-known plant, formerly called _Pyrus
japonica_, has been removed to the genus Cydonia on account of its
ovary and the disposition of its seeds, which are decidedly those of
the Quince. It differs, however, from the common Quince in its seeds,
which are arranged in two rows in each cell.
[Illustration: FIG. 30.—FLOWER AND FRUIT OF THE HAWTHORN.]
The common Hawthorn (_Cratægus Oxyacantha_) has generally only two
styles (see _a_, _fig._ 30), but the number of styles varies in the
many different species included in the genus from one to five. The
corolla, calyx, and stamens are the same as in the other genera
included in this tribe, but the petals (_b_) are rounder and rather
more indented. The seeds vary from one to five, each being enclosed in
a bony covering, or stone, the whole being surrounded by the fleshy
part of the calyx, which forms the eatable part of the Haw. In some
of the species the haws are so large as to appear like little apples;
but they may be always easily distinguished by the ripe ovary, or case
which incloses the seed, being bony; whereas in all the varieties of
Pyrus, the outer part of the ovary is cartilaginous, like the core
of the apple. The seeds of the Hawthorn are a long time before they
come up, from the hardness of this bony covering, which does not open
naturally when ripe. The species composing the genus Raphiolepis, the
Indian Hawthorn, have been separated from Cratægus; chiefly on account
of the covering which encloses the seeds being of a paper-like texture,
instead of bony, and each cell containing two seeds. The limb of the
calyx also falls off before the fruit is ripe, instead of remaining
on to form what is called an eye, as it does in the common Hawthorn.
The leaves of the plants belonging to this genus vary in the different
species; but those of the common Hawthorn are wedge-shaped, and cut
deeply into three or five lobes.
The different species which compose the genus Cratægus were formerly
considered to belong to the genus Mespilus. This genus, which is now
almost confined to the common Medlar (_Mespilus germanica_), agrees
with Cratægus in having each seed enclosed in a bony covering, but it
differs in the limb of the calyx being in large leafy segments; and in
the disk being very large and visible even when the fruit is ripe, from
the tubular part of the calyx not closing over it.
Among the plants formerly included in the genus Mespilus, may be
mentioned _Photinia serrulata_, and _Eriobotrya japonica_, both natives
of Japan. The first of these was once called _Cratægus glabra_, and
it is remarkable for its beautiful glossy leaves, which are of a deep
green when old, and beautifully tinged with red when young; the flowers
are white, and they are produced in what botanists call corymbose
panicles. There are some other species of the genus Photinia, but only
two or three are common in British gardens. _Eriobotrya japonica_, the
Loquat-tree, was formerly called _Mespilus japonica_. It is remarkable
for its large and handsome leaves, which are woolly on the under side.
The flowers, which are small and white, are produced in large panicles,
and they are followed by large pendulous bunches of the yellow
pear-shaped fruit, which is covered with a woolly substance, and hence
the botanic name Eriobotrya, which signifies woolly grapes. The tree
will stand out in the open air in England, and it will flower freely in
a greenhouse, but it requires a stove to ripen its fruit.
Cotoneaster and Amelanchier were also formerly included in Mespilus,
and they are very closely allied to Photinia and Eriobotrya. The
species belonging to Photinia, however, are easily known by their
shining leaves, and the petals of their flowers being reflexed, that
is, curved back; and the species of Eriobotrya are distinguished by
their woolliness, which spreads over even the flowers and fruit. The
Cotoneasters are known by the small petals of their flowers, which
curve inwards, and remain a long time without falling. The leaves are
also thick, and woolly or clothed with rusty hair on the under side;
and the flowers, which are produced in cymes or panicles, with woolly
pedicels, are followed by bright red haws, resembling those of the
hawthorn. Lastly, the genus Amelanchier is known by its long narrow
petals, and its ovary having five or ten cells, with five styles united
at the base.
TRIBE VI.—SANGUISORBEÆ.
The plants included in this tribe agree more or less with the common
Burnet (_Sanguisorba officinalis_). This plant, which is found in
great abundance in rich meadows on calcareous soils, has its flowers
produced in a close terminal spike. The flowers have no petals, but the
calyx, which is four-cleft, is pink, and there are four glossy brown
bracts to each flower; so that, on the whole, the flowers are rather
ornamental, notwithstanding their want of petals. There are only four
stamens, and two carpels with slender styles and pointed stigmas. The
leaves are pinnate, consisting generally of nine leaflets, and each
pair of leaflets is furnished with two stipules. The Alchemilla, or
Ladies’ Mantle, is nearly allied to the Burnet; but the flowers are in
small corymbs, instead of spikes. The flowers have no petals; but the
limb of the calyx is coloured, and divided into eight unequal segments.
There are generally four stamens and only one style, though sometimes
there are two. The ovary contains one or two carpels, each containing a
single seed, and these when ripe are enclosed in a capsule, formed by
the tubular part of the calyx becoming hardened. The leaves are lobed,
plaited, and serrated at the margin; and those of the Alpine species
(_A. alpina_), which is often found wild on the Scotch mountains,
are covered with a beautiful silky substance of the most brilliant
whiteness.