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The
Orchid Family contains the aristocrats of the plant world, with beautiful
and gorgeous flowers whose wealth of colouring and perfume is unsurpassed.
This
wonderful family contains some of the most marvelous devices to secure
cross-fertilization by the aid of insect visitors, and many orchids are
absolutely dependent on insects for the propagation of the species.
Our own
British orchids are naturally much less spectacular and conspicuous than
the great orchids of the tropics, growing under conditions of great heat
and humidity and amid abundant insect life which encourages a much greater
executive ability than our colder, less congenial climate.
All our
British orchids are geophytes, i.e. plants which root in the ground and
include two saprophytic types which, however, are plants of the woodlands.
In the
Highlands, we have eleven orchids, many of which are of common occurrence,
especially in the meadows of the valleys and lower hillsides.
They
include the Early Purple Orchis (Orchis mascula), very common in
damp meadows in early May and June; the Spotted Orchis (O. maculata),
very common in the meadows and heathy pastures; the Marsh Orchis (O.
latifolia), fairly common in damp, boggy meadows and pastures, where
one may also find its less common variety (O. incarnata); The
Butterfly Orchis (Habenaria bifolia), common in heathy pastures and
meadows; the Sweet-scented Orchis (H. conopsea), found in similar
places and just as common; the Small Orchis (H. albida), common in
heathy pastures, and the Frog Orchis (H. viridis), which may be
found in grassy meadows and on banks.
Besides
these meadowland species w also have the Creeping Goodyera, the Coralroot
and the Heart-leaved Twayblade which have been described elsewhere in this
book.
I will
endeavour in the ensuing description to describe the beautiful mechanism
by which some orchids obtain cross-pollination.
I will
commence with the Butterfly Orchis, in which the flowers are large and the
various organs of the flowers are easily discerned.
Butterfly Orchis (Habenaria bifolia)
Imagine,
if you can, a June day in Lochaber when the sun is shining in a cloudless
sky, and the soft wind blows gently up Loch Linnhe from the distant
islands, ruffling the mirror-like surface of the sea, whilst a lark is
singing high in the blue vault of heaven as he mounts steeply from his
well-hidden nest in the flower-starred meadow. The mountains rise steeply
from the sea, where their every feature is reflected in the azure depths,
towards the majestic bulk of Ben Nevis dominating the interior, his sides
slashed with slowly diminishing snow fields.
I am
standing in one of the small meadows which occupy the narrow strip of low,
fairly flat land between the sea and the steep mountain sides, and have
been wrested by the crofters from the bog and moorland with infinite
patience and toil.
These
meadows are naturally wet, and often boggy, and are intersected by the
numerous small streams that race down the mountains.
In the
south we are accustomed to see the meadows golden with Buttercups, or
white with Ox-eye Daisies, but here the meadows are filled with Orchids
and they are amazingly beautiful with the long purple spikes and handsome
spotted leaves of the Spotted Orchis and the delightful creamy spikes of
the Butterfly Orchis.
The
latter orchid is so called because the blooms are supposed to resemble a
butterfly. In this case, however, the name is not so appropriate as in
the case of the Bee Orchis of Fly Orchis, which are amazing imitations of
these respective insects.
In
Britain we have two types of this orchids; they are the Greater Butterfly
Orchis (Habenaria chlorantha), a large and very beautiful species
confined to moist woods and much more common in the south, and the Lesser
Butterfly Orchis (H. bifolia), the type so common in the Highland
meadows.
If we
were to dig up one of these orchids we should find that the short stem is
buried deep in the ground, and springs from a pair of white, fleshy,
tuberous roots, one of which is larger than the other.
The
larger tuber is a storehouse from which the present leaves and flowers
obtain their nourishment. This tuber was in existence the previous year,
whilst the other and smaller tuber is the store for nest year’s plant, and
stores up the nourishment obtained by means of its fibrous roots and the
leaves. Thus this plant can get to work to form leaves and flowers as
soon as conditions permit and independently of its fibrous roots.
Just
above the surface of the ground the Butterfly Orchis produces two fairly
large, glossy green leaves, from the middle of which springs the flower
stem. This tem has one or two scale-like leaves and its surmounted by a
dense spike of creamy, sweetly-scented flowers.
The chief
insect visitors to this plant are certain species of Hawk Moths, whose
long tongues alone can reach the nectar secreted in the long spur. The
cream-colored flowers are a good guide to those night flying insects, but
to aid them still more effectively the sweet, clove-like perfume is much
stronger in the evening than by day.
We are
now in a position to examine the individual flowers and see now they are
specialized for their insect visitors.
The
flower consists of six floral leaves, which are all petal-like and are
arranged in two whorls of three.
Of the
three outer ones, one is directed upwards whilst the other two are
spreading. Of the inner three, two are small and are situated in front of
the upwards pointing outer one. The third points downwards and forwards
and is known as the labellum. It is larger than the other segments and in
many species of orchis is the platform on which the insect visitors
alight. In this particular orchis, however, the labellum is hardly large
enough to accommodate large insects. Hawk moths hover before the flower
and have no need to alight in order to obtain the nectar, hence a landing
stage would be redundant.
The base
of the labellum is produced backwards to form a very long and narrow spur
at the base of which the nectar is secreted..
All
British orchids, except the very rare Lady’s Slipper, possess only one
stamen. The single stamen is united with the style of the ovary to form a
short column of which the anther is the apex and the stigma is the base,
and is situated directly over the entrance to the spur.
The
anther produces no pollen dust as in ordinary flowers, but tow club-shaped
bodies mounted on short stalks and attached by two adhesive discs. The
upper portion of the club is known as the polonium and consists of a mass
of pollen united together by elastic threads. When these pollinia are
ripe they are easily detached and may be removed by a needle to which they
attach themselves by the means of the adhesive discs. The polonium when
detached first stands erect, but shortly afterwards the stalk bends until
the club-shaped portion is pointing in a forward direction.
All these
specialized organs are designed towards cross-pollination. A moth seeking
to push its proboscis into the spur may quite easily detach one or both
the pollinia which adhere to its head or antennae. One can often trap
moths whose heads are covered with these small club-shaped bodies. Before
the insect arrives at another flower the pollinia have bent forward and on
its arrival are in the exact position to make contact with the stigma and
so effect cross-pollination.
It is
impossible for the Butterfly Orchis to be self-fertilized and it is thus
absolutely dependent on insect visitors. Almost all orchids are dependent
on insect for cross-pollinaton and often the scarcity or frequency of a
species in a particular area depends on the numbers of its particular
insect visitors in that area.
The plant
has also made sure that pollen from another plant shall fertilize its
blooms, and to this end has arranged its flowers in a spike.
The lower
flowers open first and a moth always commences at the bottom of the spike
and works upward to the higher newly-open flowers. From these upper
flowers it becomes covered with pollinia, which it transfers to the lower
flowers of the next flower it visits.
Another
feature which is common to most orchids is the fact that the ovary is
twisted and the whole flower is actually reversed so that in reality the
labellum is the upper petal.
Sweet-scented Orchis (Havenaria conopsea)
This
lovely little orchis belongs to the same genus as the Butterfly Orchis.
It is fonder of the wilder, more sterile pastures up to about 600 feet,
and in Lochaber is common in many such areas along with the Small Orchis,
Heaths, Sedges, etc.
It has
the same type of rootstock as the preceding except that the tubers are
divided into two or three lobes. The stem, which is about one and a half
ot two feet high, has several long, narrow leaves, and is crowned by a
dense spike of small, bright rose or purplish-red flowers which have a
very sweet vanilla-like perfume. The floral parts are small with a fairly
broad three-lobed lip. The spur is very long and slender, and is
obviously constructed to preserve the nectar for long-, very
slender-tongued insects such as the smaller types of hawk moths.
 Small
Orchis (Havenaria albida)
This
species, although belonging to the same genus as the preceding two
species, is constructed rather differently. Instead of the tuberous roots
we find that the roots are composed of several thick fibres which may be
united, in some cases, into a deeply divided tuber. The stem is only six
to eight inches high and is clothed with a few small leaves which are
glossy in texture. The stem is surmounted by a dense spike of small
cream-colored flowers which are very sweetly scented. The flowers have a
three-lobed lip and a very short spur.
This
short spur indicates that shorter-tongued insects, such as bees, must be
the chief visitors for the nectar is easily obtained by them.
It is
quite a common flower in many of the lower pastures bordering the meadows
along the shores of Loch Linnhe and I have found it in similar situations
in many other spots in the western Highlands.
Frog
Orchis (Havenaria viridis)
The Frog
Orchis which, by the way, bears little resemblance to that animal, is
fairly common in the grassy pastures and meadows and is frequently found
in the Spey Valley.
It is not
an easy plant to find as its greenish flowers render it inconspicuous
among the grasses.
The stem
produces a few ovate, smooth leaves and is terminated by a close spike of
flowers. The sepals are large and form a head over the column. The lip
is long and hanging and of a yellowish colour. Nectar is secreted in a
little pouch near the summit of the lip just below and in front of the
stigma, and also by two lateral nectarines. The pollinia in this species
take a considerable time to become depressed, this being correlated with
the time lost in visiting three nectarines in each flower. The nectar is
accessible to short-tongued insects.
Spotted Orchis (Orchis maculata)
The
Spotted Orchis is a very common plant in the Highlands and one may find
its showy spikes of flowers in damp meadows, in rough mountain pastures,
on the edges of thickets and on banks and roadsides from sea level to
1,500 feet.
The
finest specimens of this orchis that I have ever seen were in a damp,
green meadow beside Loch Linnhe, where the steep hillsides leaves but a
fringe of level ground between their rough sides and the sea, and where
tiny streams run musically through the smiling meadows to the sea. These
field were filled with orchids, but especially with the Spotted Orchis
whose handsome spotted leaves and huge, beautifully marked spikes of
flowers made a scene of beauty so remarkable that I shall never forget
it. Scattered among them were the short purple spikes of the Early Purple
Orchis, the deeper purple spikes of the Marsh Orchis and the beautiful
scented spikes of the Butterfly Orchis.
The
Spotted Orchis possesses a fairly large, tuber-like root which is divided
into two or three lobes. This is the storehouse where energy for an early
commencement of life, after the cruel winter has passed, is stored. The
tubers send up a tall solid stem which attains a height of about one
foot. The leaves, which are mostly radical, are lanceolate in form with a
bright and shining surface beautifully marked with dark purple or black
spots. The flowers are formed in a dense terminal spike, which may be as
much as three inches in length in luxuriant specimens.
They vary
much in colour, sometimes being white, more commonly pale pink, and often
of quite a dark shade. The flower consists of three dark colored sepals
which are spreading. The upper petals form an arch over the column, thus
protecting the pollinia from rain The lip is broad and usually
three-lobed, much spotted and variegated with deep rose, or even purple,
and forms a find landing stage for insect visitors. It is produced
backwards to form a log spur which contains the nectarines.
The
pollination of these flowers is very similar to that of the Butterfly
Orchis. The flowers, however, are only faintly scented and their
colouring show that large bees and butterflies are the chief benefactors.
Especially the latter, as very few bees possess a tongue long enough to
reach the nectarines at the base of the long spur.
Modern
botanists now dive O. maculata into two species known as O.
ericetorum and O. Fuchsii. The first is confined to peaty
soils with an acid reaction and is the Spotted Orchis found on
moorlands and health places. It is distinguished from O. Fuschsii
by its broad, pyramid-like spike of flowers, and by the middle lip of the
flower being small and narrow and the spur slender.
O. Fuschsii prefer less acid soils and is the
Spotted Orchis of damp meadows and pastures. It is usually a taller, more
robust species than the preceding, with a cylindrical spike of flowers
which are much marked with dark purple lines and spots, whilst the spur is
stouter than in that species. A white form of great beauty occurs, but it
is very rare.
 THE
MARSH ORCHIDS
The Marsh
Orchids are found in similar places to the Spotted Orchids, but also
prefer wetter places such as the marshy edges of lochs and streams. The
old botanists only distinguished tow species of Marsh Orchids, but today
they are divided into several species Two them, O. incarnata and
O. praetermissa, are locally common in the Highlands and are
sometimes accompanied by a third and much rarer species, O. pupurella,
which has a very limited distsribution.
These
species are not very easy to distinguish, and their diagnosis is
complicated by the fact that hybrids between the Spotted Orchids and the
Marsh Orchids are very common.
The
Crimson March Orchis (O. incarnata) is a beautiful species, and
when seen in masses, as one can often find it in boggy meadows, it makes a
fine display. It stands out well among the marsh vegetation, as its stems
often reach two feet in height and are terminated by dense, cylindrical
spikes consisting of many flesh-colured or pink flowers. The lip is
faintly three-lobed and its margin is reflexed and marked with dark spots
and streaks. A magnificent, rich purple variety occurs, but unfortunately
it is very rare; this the variety pulchella.
The
Common Marsh Orchis (O. praetermissa) is also fairly common in
certain parts of the Highlands, more so on the eastern side. It is
distinguished from the preceding by its darker colored flowers.
The third
species, O. purpurella , is distinguished from the other two by its
stem, which is more than half solid, and by its purple flowers and its
almost entire lip.
The
Early Purple Orchis (Orchis mascula)
This
orchis is another inhabitant of the moist meadows, but it is often found
in open woods and thickets. It possesses undivided tubers, which send up
stems to about one foot in height. The broadly lanceolate leaves are
spotted, although in some species these spots may be absent.
The
flowers are produced in loose spikes, which may sometimes be as much as
six inches in length. The flowers vary much in colour to flesh colour,
and even white. The lip, which is sometimes downy in the centre, is
curved down at each side and extended back into a broad spur.
They are
pollinated n a similar manner to the Butterfly Orchis, except that the
chief benefactors are bees and butterflies, especially bumble-bees. |
