THE ORDER ERICACEÆ: ILLUSTRATED BY THE COMMON OR BESOM HEATH,
THE MOOR HEATH, CAPE HEATHS, LING OR HEATHER, ANDROMEDA, LYONIA,
ST. DABÆOC’S HEATH, ARBUTUS, THE BEARBERRY, GAULTHERIA, CLETHRA,
RHODODENDRON, INDIAN OR CHINESE AZALEAS, YELLOW AZALEA, AMERICAN
AZALEAS, RHODORAK, ALMIA, MENZIESIA, LOISELEURIA, LEDUM, LEIOPHYLLUM,
THE BILBERRY, THE WHORTLEBERRY, THE CRANBERRY, PYROLA, AND MONOTROPA.
The name of Ericaceæ, which most people are aware signifies the Heath
family, conjures up immediately the image of a number of narrow-leaved
plants, with globular, ventricose, or bell-shaped flowers; and we
are apt at first to think that the family is so natural a one, as to
require very little explanation. Did the order include only the Heaths,
this would be the case, for all the Heaths, different as they are in
some particulars, may be recognised at a glance: but as the order
includes the Rhododendrons, Azaleas, and Kalmias, besides several other
plants which have not so strong a family likeness to each other as
the Heaths, it becomes necessary to say a few words on the botanical
resemblances which connect them together. The first, and most striking,
of these is the shape of the anthers, each of which appears like two
anthers stuck together, and the manner of their opening, which is
always by a pore or round hole, in the upper extremity of each cell.
The filaments, also, in all the genera, except Vaccinum and Oxycoccus,
grow from beneath the seed-vessel, being generally slightly attached
to the base of the corolla. There is always a single style with an
undivided stigma, though the capsule has generally four cells, each
containing several of the seeds, which are small and numerous. The
calyx is four or five cleft, and the corolla is tubular, with a larger
or smaller limb, which is also four or five cleft. The order has been
divided into four tribes, which I shall describe in this chapter,
though some of these are considered as separate orders by Dr. Lindley
and other botanists.
TRIBE I.—ERICEÆ.
[Illustration: FIG. 47.—THE BESOM HEATH (_Erica Tetralix_).]
This tribe, which comprehends all the heath-like plants, has been
re-divided into two sub-tribes, one containing the genera most nearly
allied to the heaths, and the other those belonging to the Andromeda.
In both there is a honey-bearing disk under the ovary, and the leaves
are generally rolled in at the margin, as shown at a, in _fig._ 47.
SUB-TRIBE I.—ERICEÆ NORMALES.
All the genera in this sub-tribe, twenty-two in number, were formerly
included in the genus Erica; and some botanists still consider all the
species to belong to that genus, with the exception of those included
in Calluna, while others adopt about half the new genera. In this
uncertainty, I shall only describe two of the doubtful genera, partly
because the distinctions between them and the true heaths are strongly
marked, and partly because the species they contain are frequently
met with in British gardens and greenhouses, where they are sometimes
labelled with their old names and sometimes with their new ones.
In the genus Erica, one of the commonest species is the Besom Heath
(_E. tetralix_), which is found in great abundance on moorish or boggy
ground in every part of Britain. In this plant, the corollas of the
flowers appear each to consist of a single petal, forming an egg-shaped
tube (see _b_ in _fig._ 47), contracted at the mouth, but afterwards
spreading into a four-cleft limb, through which is seen projecting the
style, with its flat stigma. The corolla is, however, really in four
petals, which, though they adhere together, may be easily separated
with a pin. The stamens are concealed by the corolla, but the manner in
which they grow is shown at _c_; and _d_ is a single stamen, showing
the spurs or awns at the base of the anther, the position of which is
one of the characteristics of the genus Erica in its present restricted
form; _e_ is a capsule with the style and stigma attached; and _a_
is a leaf showing its revolute or curled back margin. The leaves of
this species are in whorls, four leaves in each whorl, and they are
ciliated, that is, bordered with a fringe of fine hairs.
[Illustration: FIG. 48.—BELL-SHAPED HEATH.]
[Illustration: FIG. 49.—CAPE HEATH. (_E. hispida._)]
All the true Heaths bear more or less resemblance to this plant. In
some, the corollas are bell-shaped, spreading out at the tip into five
teeth, which inclose the stamens, as shown in _fig._ 48; and in others
they are nearly globose swelling out near the calyx, and tapering to
a point, beyond which the stigma and anthers project; as in the Cape
Heath, called _Erica hispida_, a flower of which is shown in _fig._
49. The leaves also differ exceedingly, in the number contained in
each whorl; as in some species there are only three in a whorl,
while in others they are five or six. The general features of all the
Heaths are, however, the same—viz., there are eight stamens, which are
generally inclosed in the corolla, though they sometimes project beyond
it, as shown in _fig._ 49, and the anthers of which are two-cleft, and
awned or crested at the base, while the filaments are hair-like; one
style, which always projects beyond the corolla, and has a flattened
stigma; a four-parted calyx and corolla which is tubular, with a
four-parted limb. There are nearly two hundred species of this genus,
some of which are natives of Europe, and others of the Cape of Good
Hope.
The moor Heaths (_Gypsocallis_) were separated from the genus Erica,
by Mr. Salisbury, principally on account of the corolla being
campanulate, or shortly tubular, with a dilated mouth; and the stamens
projecting beyond the corolla. The filaments are also generally flat;
the anthers are without awns, and distinctly in two parts; and the
stigma is simple, and scarcely to be distinguished from the style. The
common Cornish Heath (_G. vagans_), and the Mediterranean Heath (_G.
Mediterranea_), are examples of this genus, which appears strongly
marked, though, as I before mentioned, some botanists do not adopt it.
Callista is a genus established by the late Professor Don, which
appears very distinct, though it also has not been generally adopted.
It includes all those beautiful Cape Heaths which have a shining,
glutinous, ventricose, or cylindrical corolla with a spreading limb
(see _a_ in _fig._ 50), and a capitate stigma (_b_). _C. bucciniflora_
and _C. ventricosa_, are examples of this genus.
[Illustration: FIG. 50.—CALLISTA BUCCINIFLORA.]
The Ling or Heather, which Linnæus called _Erica vulgaris_, is now
generally placed by all botanists in a separate genus called Calluna,
which was established by Mr. Salisbury. The calyx of this plant is
membranous, and coloured so as to resemble a corolla, and it is
furnished with four bracts at the base, which resemble a calyx. The
true corolla is bell-shaped, and shorter than the calyx. The stamens
are inclosed, and the anthers are of the very singular form shown in
_fig._ 51. The stigma is capitate, and the flowers are disposed in what
is called a racemose spike. The leaves are trigonal; they are very
short, and they are laid over each other like scales in four rows. The
Ling is the only species in the genus.
[Illustration: FIG. 51.—STAMEN OF THE LING.]
SUB-TRIBE II.—ANDROMEDEÆ.
The plants in this sub-tribe differ decidedly from those of the
preceding division, in having ten stamens, while all the genera of
heaths have only eight. The calyx is also five-cleft instead of
four; and the corolla, which falls before the seeds are ripe, has a
five-lobed limb. The sub-tribe is divided into twenty genera, more than
half of which are perfectly distinct.
[Illustration: FIG. 52.—STAMEN OF ANDROMEDA.]
The genus Andromeda is distinguished by its globose corolla which has
a five-lobed limb; and its stamens which have their filaments bearded,
and their anthers short and two-awned. _Fig._ 52 shows a stamen of the
wild rosemary (_Andromeda polifolia_) with its bearded filament (_a_),
and its two-awned anther with its pore-like openings (_b_). The cells
of the capsule open in the middle, down the back, to discharge the
seeds. Professor Don has divided the genus Andromeda into six genera;
some of which contain only one or two species. Thus only _Andromeda
polifolia_ and _A. rosmarinifolia_ are left in the genus Andromeda;
Cassandra contains only _A. calyculata_, and _A. angustifolia_; and
Zenobia, only the beautiful _Andromeda speciosa_. In Cassandra the
anthers are long and mutic (see _a_ in _fig._ 53), and the leaves (_b_)
are without veins, and white and full of dots on the underside, the
edges being curled inwards; and in Zenobia the corolla is bell-shaped,
with the limb, which is in five lobes, curling back (see _a fig._ 54).
The stamens have the filaments (_b_) curiously dilated at the base;
and the point of each cell of the anther is cut into two erect awns
(_c_). The manner in which the stamens are arranged inside the corolla
is shown at (_d_). The cells of the capsule, when ripe, open down the
centre, and the seeds which are angular, are attached to a five-lobed
placenta.
[Illustration: FIG. 53.—LEAF AND ANTHER OF CASSANDRA.]
[Illustration: FIG. 54.—FLOWERS, COROLLA, AND STAMEN OF ZENOBIA.]
Lyonia is a genus established by the American botanist Nuttall, because
the plants it contains have the margins of the valves of their capsules
closed by five other narrow external valves. The plants are natives of
North America, and their flowers are generally small. _Lyonia Mariana_
may serve as an example of this genus, which is generally adopted by
botanists.
It would be useless to enter into details of the other genera formed
out of Andromeda, as they are not generally adopted; but, perhaps, it
may be worth mentioning, that the well-known _Andromeda floribunda_ is
placed by Professor Don in a new genus which he calls Leucothoe.
St. Dabeoc’s Heath, or Irish Whorts, a little heath-like shrub, common
in Ireland, is one of those plants which have puzzled botanists
exceedingly. It has been called successively _Erica_, _Andromeda_,
and _Menziesia_, _Dabœcia_; then _Erica Hibernica_, next _Menziesia
polifolia_, then _Vaccinium Cantabrieum_ and lastly _Dabœcia
polifolia_. It is probable, however, that it may even yet be doomed to
undergo other changes; as, from the construction of its anthers, which
are linear, and arrow-shaped at the base, and which open lengthways,
instead of by pores, it does not appear even to belong to the Ericaceæ.
The other genera in this sub-tribe are quite distinct from each other,
and contain several well-known plants. The most popular of these genera
are Arbutus, Arctostaphylos, Gaultheria, and Clethra.
[Illustration: FIG. 55.—FRUIT &C. OF ARBUTUS UNEDO.]
The Strawberry tree (_Arbutus Unedo_) has little bell-shaped flowers,
contracted at the mouth, and with a curling-back limb, which are easily
recognised as belonging to the Ericaceæ. They have ten stamens, the
filaments of which are hairy at the base (see _a_ in _fig._ 55) and
inserted in the disk; which in this genus is large, and rises up round
the ovary (see _b_). The calyx is permanent, and five-cleft; and the
flowers are produced in panicles, and each is furnished with a bract.
The fruit, which retains the calyx when ripe, is a granular berry,
covered with tubercles on the outside; and it has five cells (_c_)
containing the seeds. There are numerous varieties of this species
common in British gardens, besides a very beautiful hybrid between
it and _A. Andrachne_. The latter species is a native of Greece, and
rather more tender than the common kind; and it is very conspicuous in
shrubberies from its red stems and loose bark.
The Bearberry (_Arctostaphylos Uva-Ursi_) was formerly considered to
belong to the genus Arbutus, but it differs in the filaments of the
stamens being smooth and dilated at the base, and the awns affixed to
the middle of the anthers. The berry is without tubercles, and the
cells are often only one-seeded.
There are two species of Gaultheria common in British gardens: viz.—_G.
procumbens_ and _G. Shallon_: both of which have flowers resembling
those of the Arbutus and furnished with bracts; but in the former
species the flowers are solitary and produced from the axils of the
leaves, and in the latter they are in racemes, of the kind called
secund, that is with the flowers growing all on one side. The berries
of both kinds are eatable, and those of _G. procumbens_ are called
Partridge berries in America, and the leaves Mountain tea. Both species
have ten stamens, the anthers of which are two-cleft, each cell being
furnished with two horns, as in _Zenobia speciosa_ (see _fig._ 54, in
page 116). The fruit is five-celled and the seeds are numerous.
[Illustration: FIG. 56.—FLOWER OF CLETHRA ALNIFOLIA.]
The genus Clethra differs considerably from the preceding genera, as
the limb of the corolla is so large and so deeply cleft, as to make the
flower appear to have five petals (see _a_ in _fig._ 56). There are
ten stamens, with broad arrow-shaped anthers (_b_), and a three-cleft
stigma, (_c_). The capsule is dry, with three many-seeded cells. In _C.
alnifolia_, a native of North America, (of which _fig._ 56 represents
a magnified flower,) the flowers are erect, and produced in a spicate
raceme; but in _C. arborea_, a native of Madeira, the racemes are
panicled, and the flowers drooping and somewhat bell-shaped. Both
species are very ornamental.
TRIBE II.—RHODOREÆ.
The plants included in this tribe are all considered to bear more
or less resemblance to the Rhododendron, though in some of them the
family likeness is not very strong; and the genera I shall describe
to illustrate it are Rhododendron, Azalea, and Rhodora (the last two
being by some botanists included in Rhododendron); Kalmia, Menziesia,
and Ledum.
[Illustration: FIG. 57.—BACK VIEW OF A FLOWER OF RHODODENDRON MAXIMUM,
AND SEED-POD.]
[Illustration: FIG. 58.—FLOWER OF RHODODENDRON PONTICUM.]
The species of the genus Rhododendron are easily distinguished by
their flower buds, which are disposed in the form of a strobile, or
pine-cone, each bud having its accompanying bract, which the flower
retains after its expansion, as shown in _fig._ 57 at _a_, in a flower
of _R. maximum_. There are five or ten stamens of unequal length, the
larger ones curling upwards (as shown at _b_ in _fig._ 58), as does the
style (_c_), which has a simple stigma. The flowers have a very small
calyx, (_d_ in _fig._ 57,) and a campanulate corolla which is deeply
five-cleft, the upper segment (_e_ in _fig._ 58) being somewhat larger
than the rest, and spotted in the inside. The capsule is five-celled
and five-valved, as shown in _fig._ 57 _f_. The leaves of nearly all
the species are evergreen; and the flowers are showy, and produced in
terminal corymbs. The principal species may be thus distinguished from
each other; _R. maximum_ has drooping leaves, covered with brown or
white down on the under surface, and a dense corymb of flowers, the
segments of the corollas of which are roundish, and the bracts leafy.
In _R. ponticum_, on the contrary, the corymbs of flowers are looser,
the segments more pointed, and the bracts more scale-like; and the
leaves are smooth on both surfaces. The seed-pods also differ: in
those of _R. maximum_ and the other American species, the valves are
smooth as shown at _f_ in _fig._ 57; and in those of _R. ponticum_, the
valves are somewhat crinkled as shown in _fig._ 59. This species, and
all its hybrids and varieties, are more tender than _R. maximum_, _R.
catawbiense_, and all the other American kinds and their offspring.
_R. catawbiense_ has the flower of a darker colour on the outside of
the corolla than within, and the upper segment is very faintly dotted.
It hybridises freely with _R. arboreum_, which _R. maximum_ does not,
and the hybrids thus produced are hardier than those raised from _R.
ponticum_, though the latter are by far the most numerous.
[Illustration: FIG. 59.—SEED-POD OF RHODODENDRON PONTICUM.]
Most of the species have purple or whitish flowers, but some, such
as _R. chrysanthemum_, and _R. anthopogon_, have yellow flowers; _R.
ferrugineum_ and _R. hirsutum_, have bright pink or rose-coloured
flowers; and those of _R. arboreum_ the Nepaul tree Rhododendron, are
of a rich scarlet. The commonest small kinds are _R. ferrugineum_ and
_R. hirsutum_, both dwarf shrubs and natives of the north of Europe,
with funnel-shaped corollas, and leaves dotted on the under surface.
They are so much alike as scarcely to be distinguished at first sight,
but on examination the leaves of _R. ferrugineum_ will be found to have
brown dots, and to be plain on the margin; while those of _R. hirsutum_
have white dots and are fringed with fine hairs.
Of all the species of the genus, those which differ most widely
from the others are the Indian kinds. Of these _R. arboreum_ has
a ten-celled capsule, and the segments of the corolla two-lobed
with waved margins. The leaves are long and silvery beneath; and
the capsules, the peduncles, and the calyxes, are all woolly. In
_R. campanulatum_, a splendid species with very large flowers, the
capsule is six-celled, the leaves are somewhat cordate at the base,
and the bracts are fringed; and in _R. anthopogon_ the corolla has
a cylindrical tube, woolly inside, and a small but spreading limb,
cut into five lobes. There are eight stamens, and the capsule is
five-celled.
_R. Camtschaticum_, _R. Chamæcistus_, and _R. dauricum_ differ from
the preceding species in having their corollas rotate, that is,
wheel-shaped. The last of these kinds is a favourite greenhouse shrub,
from its flowering under shelter in winter. In the open ground it
flowers in March. The species has rose-coloured flowers which appear
before the leaves; and leaves which turn red in autumn before they
fall. The roots are knobbed and fibrous; and the stems are twisted and
knobbed in a wild state. There is a variety _R. d. atrovirens_ which
has purple flowers, and evergreen leaves, and which is hardier than the
species.
The genus Azalea may be divided into three kinds, viz., _A. indica_
and its allied species; _A. pontica_ and its varieties and hybrids;
and the American Azaleas. These divisions are easily distinguished by
their flowers. Those of the Indian or Chinese Azaleas have all large
showy flowers, on short downy footstalks, and they are produced in
small clusters of only two or three flowers each, at the extremity
of the shoots. The corollas are bell-shaped and deeply cut, nearly
to the base, into broad spreading segments. The stamens are ten in
number, shorter than the corolla, and of unequal length. The leaves are
evergreen, and they are numerous, thickly set and downy. These Azaleas
are all very handsome, but the white Indian Azalea (_A. indica alba_,
or _A. ledifolia_) is particularly so, and very fragrant. The species
belonging to this division are mostly natives of China, and require
either a greenhouse or some slight protection during winter in England.
The yellow Azalea (_A. pontica_ or _Rhododendron flavum_) differs from
_A. indica_ in being quite hardy; in the flowers being produced in
umbels of from eight to twelve, at the ends of the branches, before the
leaves; and in the corollas being funnel-shaped instead of campanulate.
The tube of the funnel is, however, shorter than the limb, the segments
of which are broad and spreading, the upper three being larger and of
a darker yellow than the two below. There are usually five stamens,
projecting a little beyond the corolla, and curving upwards; the style
also curves upwards, and it is crowned by the stigma, which forms a
round green head.
The calyx is very small, and both it and the corolla feel clammy to the
touch. The flowers are fragrant. The leaves are deciduous, and they are
ovate, slightly hairy, and terminate in a mucro or stiff point. There
are many varieties of this species, and many hybrids between it and the
American kinds, all of which are quite hardy in British gardens.
The principal American Azaleas are _A. nudiflora_, _A. viscosa_, _A.
nitida_, and _A. speciosa_, all of which have the corollas of their
flowers funnel-shaped. Of these _A. nudiflora_ is easily known by its
stamens, which project a long way beyond the corolla, and by the tube
of the corolla being longer than the limb. The plant is deciduous; and
the flowers, which are produced in large terminal clusters, and which
are not clammy, appear before the leaves. The common English name for
this plant in some parts of the country is the American Honeysuckle,
and the flowers are of various shades of red, pink, white, and purple.
_A. calendulacea_, which some botanists make a variety of this species,
has much larger flowers, and the leaves pubescent on both surfaces,
whereas, in _A. nudiflora_ the leaves are nearly smooth and green, with
only a slight fringe of hairs round the margin. There are numerous
varieties of _A. calendulacea_, the flowers of which are always either
yellow, red, orange, or copper-coloured, and it is supposed to be the
parent of the beautiful Ghent Azaleas. _A. viscosa_ has the tube of
the corolla equal in length to the limb, and rather short stamens; the
flowers of this species are clammy. _A. hispidum_, which is generally
considered a variety of _A. viscosa_, is still more clammy, and the
tube of the corolla is wider and shorter; other probable varieties
are _A. nitida_, which has shining leaves, and _A. glauca_, which
has glaucous ones, as in both kinds the flowers are very clammy. _A.
speciosa_ has large flowers and leaves tapering at both ends. All the
species of Azalea have five stamens, but some of the varieties have ten.
_Rhodora canadensis_ is a little American shrub with pink flowers,
which appear before the leaves, and the corolla of which is bilabiate,
the upper lip being the broadest, and cut into two or three teeth, and
the lower only once cut. There are ten stamens, and the capsule is
five-celled and five-valved. The leaves are deciduous, and slightly
pubescent beneath; and the flowers are produced in small terminal
clusters. This plant, as well as all the Azaleas above described, are
now included by some botanists in the genus Rhododendron.
The genus Kalmia also belongs to this tribe. The flowers of this
well known shrub are very curiously constructed. The corolla is
salver-shaped, that is, nearly flat, and on the under side of the limb
are ten protuberances, producing as many hollows on the upper side,
in which lie half-buried the ten stamens. This singular construction
gives the corolla that wrinkled appearance which has procured for the
plant its American name of Calico flower; while, from the shape of
the leaves, it is also frequently called the Mountain laurel; it is
also called Sheep laurel from its being considered poisonous to those
animals when they feed on it. There are several species, which differ
from each other principally in the shape of their leaves and the size
of their flowers.
_Menziesia_ is a genus containing only three species, of which _M.
pilosa_ (_fig._ 60) may be taken as an example. The flowers are
small and bell-shaped, and the anthers (_a_) are without any awns or
bristles; there are eight stamens, and the curious manner in which they
are crowded round the style is shown at _b_. The capsule is four-celled.
[Illustration: FIG. 60.—FLOWERS, ANTHERS, AND PISTIL OF MENZIESIA.]
_Loiseleuria_, or _Azalea procumbens_, is a small plant, having the
appearance of thyme, which is the only species left in the genus
Azalea by those botanists who include the true Azaleas in the genus
Rhododendron.
_Ledum_ is the last genus belonging to this tribe that I shall attempt
to describe. _Ledum palustre_, or wild Rosemary, the best-known
species, has a corolla in five regular petals, and ten stamens which
project beyond it; but _L. latifolium_, the Labrador Tea, has only five
stamens, which are not longer than the petals. _L. buxifolium_, a
little thyme-like shrub, is now called _Leiophyllum thymifolium_. All
the species have white flowers.
TRIBE III.—VACCINIEÆ.
[Illustration: FIG. 61.—COMMON BILBERRY (_Vaccinium tenellum_).]
The plants comprised in this tribe, which is considered a separate
order by many botanists, all agree with the genus Vaccinium in having
the ovary entirely surrounded by the calyx, which forms a fleshy
berry-like fruit when ripe, and in the seeds being scaly. _Vaccinium
Myrtillus_, the common Bilberry or Blaeberry, is a familiar example
of the genus; and _fig._ 61 shows the shape of the flowers at _a_,
the manner in which the ovary is enveloped in the calyx at _b_, and
the curious shape of the anthers in the magnified representation of
them at _c_. The berry is five-celled and many-seeded; and there are
eight or ten stamens. Both the anthers and the flower vary in the
different species, but the calyx and the manner in which it surrounds
the ovary are nearly the same in all, as may be seen in _fig._ 62,
which represents a specimen of _V. tenellum_, the Pennsylvanian
Whortle-berry. In this figure _a_ is the flower, _b_ the anther, and
_c_ the ovary surrounded by the calyx.
[Illustration: FIG. 62.—AMERICAN WHORTLE-BERRY (_Vaccinium
pennsylvanicum_).]
There are many species, among which may be mentioned the American
Bluets (_V. angustifolium_); Deerberries (_V. stamineum_); Bluetangles
(_V. frondosum_); the Hungarian Whortle-berry (_V. Arctostaphylos_);
and the Cow-berry, or common British Whortle-berry (_V. Vitis-Idæa_).
[Illustration: FIG. 63.—CRANBERRY.]
The Cranberry (_Oxycoccus palustris_) differs from the genus Vaccinium
in the shape of its flowers (see _fig._ 63), and in its anthers being
without spurs; there are eight stamens, the filaments of which are
connivent, that is, growing close together. The American Cranberry (_O.
macrocarpus_) differs from the European kind, principally in having
larger fruit.
TRIBE IV.—PYROLEÆ.
This tribe is also considered as a separate order by many botanists;
but the principal distinction is the long arillus or skin which
enfolds the seeds and gives them the appearance of being winged.
The most remarkable genera are _Pyrola_, the Winter Green, of which
there are several species common in moist woods in the north of
England and Scotland; and _Monotropa_, or Bird’s-nest, parasitic
plants which grow on the roots of pine and beech-trees, but are by
no means common in England. The species of Pyrola are pretty little
evergreen plants, with white flowers, the corollas consisting of five
distinct petals, and which have ten stamens, the anthers of which are
two-celled, each opening by a pore; the style is single, ending in a
capitate stigma cut into five lobes; and the capsule is five-celled.
The yellow Bird’s-nest, (_Monotropa Hypopitys_) has a coloured stem,
with drooping flowers, and numerous scales instead of leaves, of which
it is destitute. The flowers have a coloured calyx cut into four or
five segments, and the corolla is in four or five petals. There is an
American species with white flowers.