Amphibious Persicaria (Polygonum amphibium)
This is a
very common plant in tarns, streams and watery places, and its handsome
spikes of rose-pink flowers brighten the surface of the shallower waters.
As it forms large colonies the effect is heightened.
thick, hollow stems, which have much swollen nodes, creep along the mud at
the bottom of the pool. From the nodes are given off many tough,
much-branched, fibrous, reddish roots which anchor the plant firmly and
prevent it from being dragged away by currents. The creeping stem becomes
erect at the extremity, branches profusely, and rises to the surface of
the water. Here it produces several long-stalked, oblong leaves which
float on the surface and help to buoy up the stem. From the nodes more
branching roots hang down in the water and help to supply the large plant
with water and mineral salts.
examined the leaf, we should see that at its base is a cylindrical,
membranous sheath which embraces the stem. This is actually the leaf
stipule, but it is known as the ochrea. We should notice that the leaves
are shiny above and it is on this surface that the stomata are found.
flowers are produced from the summit of the stem in dense spikes supported
on tall, stout peduncles. Each flower consists of a pink, bell-shaped
corolla, from the base of which arise four stamens whose long filaments
project beyond the mouth of the bell.
ovary is terminated by two erect styles with stigmas like pin-heads. The
surface of the ovary has a depression all round it and in this nectar is
stamens mature before the stigmas and in a young flower the styles are
twisted together, but when all the pollen is shed, the anthers drop off
and the two styles spread apart. A bee on visiting the flower must push
its head into the corolla to reach the nectary and will leave transported
pollen upon the stigmas. Self-pollination is obviously impossible. To
ensure that bees will visit the flowers, the conspicuous spikes are
INHABITANTS OF THE LOCH FRINGES
described the inhabitants of the Highland lochs, we must now make the
acquaintance of some of the interesting plants that inhabit the shallow
edges and marshy shores of these delightful stretches of water. The
delta-like areas formed around the mouths of small streams which run down
into these lochs are especially rich in littoral plants.
places we shall find the stately Yellow Iris, with its large, handsome
flowers, the beautiful fringed chalices of the Bog-bean, the bright blue
spikes of the Water Lobelia, the large Water Plantain with its spikes of
tiny flowers and many others, such as the Water Avens, the Marsh
Cinquefoil and the Meadow Sweet, which have been described elsewhere in
include many interesting plants and among them we shall find many
adaptations to habitat and insect visitors. A visit to the shores of any
Highland loch is very illuminating, offering as it does a chance to study
Nature under ideal conditions and amid beautiful scenery. All these large
sheets of water have a beauty of their own enhanced by the floral wealth
along their shores.
commence with a typical inhabitant of the shallow loch fringes, the Water
Water Lobelia (Lobelia Dortmanna)
species is quite a common plant in the shallow water around the shores of
many Highland lochs. In Speyside it is very common in all the many lochs
of Rothiemurchus and it is there that I first made the acquaintance of
this lovely plant.
Lobelia usually forms a carpet of green leaves beneath the surface of the
water, sometimes completely submerged with a part of the leaves above the
water. The individual plant has a root system of fine roots which anchor
the plant in the mud and stones at the bottom of the lake. The rootstock
is crowned by a tuft of bright green, radical, cylindrical leaves, which
are very peculiar, for they are formed of two hollow tubes placed side by
side. As we know, a tube is one of the strongest forms of architecture
and thus, the leaves of the Water Lobelia are well adapted to withstand
currents and also the strong waves which often beat upon the shores of the
tufts of leaves arise leafless flower stalks which attain a height of from
nine inches to one foot. They are terminated by a spike of three or four
distant flowers, the flower stems consisting of a single cylindrical tube.
flowers themselves are peculiar structure. They possess a tiny green
calyx from which protrudes the long tubular corolla which is slit open to
the base on the upper side. The tube is more or less two-lipped at the
entrance and irregularly lobed.
flowers show us the transition from the perfect bell-shaped corolla of the
Bellflowers to the strap-shaped tubular florets of the Composites.
base of the corolla-tube we shall find the ovary and the nectarines. The
ovary is surmounted by the long hairy style, while in a newly-opened
flower we shall find that the anthers of the five stamens are pressed
close against the style. At this stage the three stigmatic surfaces are
pressed close together so that there is no chance of self-fertilization.
At a later stage, when the stigmas are well clear of the anthers, the
filaments retract and pull the anthers away from the style towards the
base of the tube, while the three stigmatic lobes unfold to expose their
description it is obvious that a bee visiting a flower will leave pollen
upon the stigmas at the entrance and then, as it pushes its head into the
tube, it will become dusted with pollen still adhering to the hairy
style. In this species, the flower is so well adapted that
self-fertilization is well nigh impossible.
whose favourite colour is blue, are the chief benefactors as their tongues
alone are long enough to reach the nectarines, and as they must push their
heads into the tube to do this, they become dusted with pollen.
same time, their habit of commencing at the bottom of a spike of flowers
mans that they will visit the older pistillate flowers at the base of the
spike first, thus assuring pollination with pollen from a distinct plant.
we see how amazingly bees and flowers have evolved for the common good of
Bog-bean (Menyanthes trifoliata)
edges of lochs, tarns and streams, especially in shallow muddy places,
where inflowing streams have formed swampy deltas, we may find this
strange, beautiful, little plant.
had the pleasure of studying its lovely flowers in a little pond covered
with Pondweed and fringed with Irises, Lousewort, and Marsh Cinquefoil, on
the edge of the sterile Moor of Granish in Speyside. Since then I have
found it in many different parts of the Highlands.
It is a
typical aquatic plant with a thick rootstock which creeps in the mud at
the bottom of the loch, sending out dense growth of matted roots into the
mud in search of food and anchorage. The rootstock sends up a thick stem
which in deeper water may float upon the surface, but in shallow water
creeps along the mud. The stem produces a dense tuft of leaves which have
along, thick stalk and a long, thick stalk and a long, white sheathing
base. The leaves consist of three large ovate leaflets, which are quite
smooth, as in most aquatics, and usually stand erect above the surface of
the water. From the base of the tuft of leaves arises the thick
flowerstalk which may attain as much as one foot in height. It is
leafless and crowned by a raceme of beautiful white flowers, which are
often delicately tinged with pink.
individual flower is an interesting and beautiful structure. It consists
of a short green calyx from the base of which arises the bell-shaped
corolla crowned by five deeply cut lobes which usually recurve. The outer
surface of the corolla is of a reddish hue shading to white and is quite
smooth, but within the petals are covered with a thick mantle of hairs.
These hairs prevent crawling insects and small insects with short tongues
from reaching the nectarines at the base of the bell. As these insects
would otherwise steal the nectar, and by their smallness miss the anthers
and stigmans, they could not benefit the plant.
examine flowers from different plants, we find that in some the style is
long, the stigma occupying a position at the mouth of the bell and that in
these cases the stamens only arise half-ay up the inside of the bell. In
others, the stamens are long, reaching the mouth of the bell while the
style is short. This is the same construction as in the primrose and is
another example of heterostylism.
that flower a full yield of seed is only obtained when pollen from the
long stamens is transferred to a long-styled pistil and vice-versa. Any
pollen transferred from the long stamens to the short-styled pistil will
be almost infertile. Thus has the Bog-bean ensured cross-pollination. As
this plant forms large colonies along the loch shores, the chance of a
legitimate transfer of pollen is great, for many flowers of the two types
will be found in close proximity.
the chief visitors to this plant as only they possess a tongue long enough
to pass between the hairy filaments and reach the nectarines at the base
of the bell.
Greater Skull Cap (Scitellaria galericulata)
summer’s day I was exploring the boulder-strewn shore of Loch Lomond,
between Luss and Tarbett, where the craggy mountains drop almost sheer to
the water’s edge and where the shapely peak of Ben Lomond dominates the
landscape. Here, where one obtains charming views across the loch to
Rowardenan and down the island-studded lower portion towards Balloch, I
first discovered the Greater Skull Cap.
stream came tumbling joyfully down the rocky hillside rushing into the
loch by a verdant mossy-green channel. Here large tufts of the Greater
Skull Cap with its beautiful deep blue flowers grew out from the chinks of
rock along the cool water course, and I was able to watch a large
bumble-bee diligently visiting each flower, unaware of the interest being
taken in it.
Cap genus (Scutellaria), a member of the Labiate Family, is large
and widespread although in Britain we have but two native species.
Greater Skull Cap is a fairly frequent plant in damp rocky places beside
streams and rills, although I have not found it very often in the Highland
area, it is certainly common enough along the shores of Loch Lomond.
possesses a creeping rhizome which gives off fine roots which are well
able to push down into the crevices of the damp rock on which it loves to
grow. It sends up many weak stems which often hang down gracefully and
attain about one foot in length. The stems are clothed by many pairs of
sessile leaves which are ovate-lanceolate in shape and slightly toothed
and covered with a slight down. In the axils of these leaves arise pairs
of beautiful blue flowers which are produced along the greater part of the
stem and they all face in the same direction. Thus the inflorescence is
in reality a long interrupted spike. The corolla consists of a long tube
which is very slender in the lower part, but is much wider above, in order
to permit the bee to enter the flower. It is terminated by a pair of
lips, the upper one of which is concave, whilst the lower one is
flowers, which are typical of the Labiate Family, are adapted for bees,
especially the larger types.
dissect a single flower, we shall find that the ovary is situated at the
base of the slender tube where the nectarines are also situated. The
ovary is surmounted by a long slender style which is curved near the apex
in order to fit into the concave upper lip. The two stigmatic surfaces
project downwards. The four stamens lie parallel to the style in the roof
of the mouth, but two to them are shorter than the other two and lie
farther back. The concavity of the upper lip protects the anthers
beautifully against rain and damp.
the anthers only are mature, but later after the pollen has been shed the
stigmas become receptive. A bee on visiting the flower alights on the
lower lip, and forcing its head into the mouth of the tube to reach the
nectar at its base, becomes dusted on the top of the head and the back by
the anthers in the upper lip. On going to an older flower with mature
stigmas, it is obvious that its pollen-covered head and back must come in
contact with the stigmas which are in the same position as the anthers
occupied. Thus cross-pollination is assured.
the larger bees have long enough tongues to reach the nectar, they are the
only visitors. From their habit of visiting the lower flowers of a spike
first, i.e. the older flowers with mature stigmas, it is obvious that they
will always pollinate these flowers with pollen transported from another
plant or stem which is just what the plants wants.
then, is another example of how amazingly flowers are adapted to their
insect visitors and how hard they strive to avoid self-fertilization.
Iris (Iris Pseudacorus)
us must be familiar with the stately, purple, blue and white Irises, which
form such splendid beds in most ornamental gardens. Their erect posture
and their sword-like leaves enhance their military bearing, whilst their
velvety petal rival those of the Orchid in colour and form.
garden Irises are, for the most part, natives of dry countries and do not
need more water than the other inhabitants of the garden. In this our
present subject is very difficult as it can only flourish where it can
obtain abundant moisture.
Yellow Iris is a very common plant throughout Britain and is quite common
in the lower parts of the Highlands. It prefers the shallow fringes of
lochs, the edges of streams and swampy places, whoever the soil is soft
enough for its roots to penetrate and where the soil is not too acid.
it one June growing in profusion within a stone’s throw of the sea,
forming a dense mass of vegetation along the muddy edge of Loch Morar,
just where that delightful sheet of water hurls itself in showers of spray
into the Morar River to dash in impetuous glee into the nearby sea. From
this charming spot one looks out over the silver Minch to the sharp points
of Rum and romantic Coolins, and if the time be near sunset and the sun is
descending in crimson glory, few of Nature’s master pieces can rival the
magnificence of the scene.
Yellow Iris is a perennial and forms extensive colonies. Its main stem is
a thick, creeping rhizome which lies upon the surface of the mud and is
usually immersed several inches in the water. It gives off many thick
white roots, which penetrate deeply into the mud.
rhizome is dug up and a transverse action is cut, it will be found to
consist of a sold white tissue containing many oval yellowish spots.
These spots represent the vascular bundles of the rhizome and contain the
vessels by which water, salts, and other food products are distributed to
the various parts of the plant. If a drop of iodine is placed upon the
section a deep blue coloration will be given, due to the abundant starch
grains stored up in the cells. During the winter this store of food
remains safely at the bottom of the lake, where frost and cold cannot
rhizome sends out branches and in the course of time large areas are
colonized by a single plant. On decay of the intervening portions of the
rhizome, the daughter plants become independent of the parent. This is a
means of reproduction by vegetative process.
spring, when the water begins to get warmer, a large bud at the extremity
of the rhizome commences to swell and, fed by the starch in the cells, it
sends up a bunch of radical leaves.
sword-shaped, very acute, rather glaucous leaves attain as much as three
to four feet in height and are remarkable for the fact that they possess
no under surface, but stand erect. They are very strong and are not
likely to be damaged by strong winds, and as they have a large surface
area, they are very efficient assimilating organs.
midst of the leaves arise one or several tall, stout, cylindrical stems
upon which the flowers are borne. They bear very large, leafty bracts
very similar to the foliage leaves in form, and from the upper two or
three of which are produced the large showy flowers. Whilst young the
flower bud is safely hidden in the hollow sheathing base of the leaf.
flower, when in bud, is beautifully wrapped up in membranous, translucent,
boat-shaped bracts, the one enveloping the other, but as the flower
develops, it gradually burst out of the sheath.
fully-opened bloom is a very beautiful structure indeed and can well claim
a place among our most lovely flowers. Only in the Orchid Family do we
find such a modification of structure and such nice adaptation to insect
flower is large and complicated. The corolla (or as it is called, the
perianth) consists of six petals in two whorls, of which the three outer
ones have a large, broad, ovate blade which is bright yellow in colour.
The blade narrows into along claw which is united to the claws of the
inner petals to form a long tube. The lower portion of the blade has a
brown hart-shaped mark at its base, with deeper yellow colouring within.
Brown veins run down to the base of the claw and guide the bees to the
entrance of the perianth tube. These outer petals curve down gracefully
and form a fine landing stage for insects.
inner petals are very small and much less conspicuous, the blade being
narrow, spoon-shaped, and bright yellow in colour.
examine the flower, we shall see that in addition to the petals there are
three large, erect, conspicuous, bright yellow, petal-like objects which
curve upwards from the centre of the flower. These structures are
actually the styles and stigmas, the tip of the style being expanded into
a much-cut fringe below which and on the under side of which, is a tiny,
raised ridge which is the actual stigma.
flower contains three stamens, whose anthers are produced under the
over-aching style which protects the pollen from rain and damp.
is a smooth, cylindrical structure at the base of the perianth tube and is
concealed in the bracts. Nectar is produced by the glandular summit of
the ovary and it often almost fills the perianth tube.
end has this beautiful, complicated structure been evolved? This is best
answered by gong to the nearest loch-side in June and watching the
bumble-bees at work. As we watch a particular bloom, we may be rewarded
by the flash of closing wings as the large insect alights upon the broad
outer petal. Without wasting any time and guided by the brown veins it
pushes its head down between the overhanging style and petal, any pollen
upon its head and back being scraped off by the ridge-like stigma. The
bee then brushes its back against the anthers. By this time it can push
its long proboscis into the perianth tube and suck up the nectar. It then
flies off to the next bloom with a good cargo of pollen upon its back
ready for the next stigma that it touches. Thus the flower has assured
fertilization the ovary swells to form a large ovoid capsule which splits
into three divisions to display the bright, orange-red seeds.
Loosestrife (Lythrum Salicaria)
beautiful plant is confined mainly to the western Highlands and does not
penetrate far into the northern Highlands. It is surely one of the
loveliest denizens of our marshlands, its tall, purple spikes dominating
the loch shores, river and stream sides and the wet meadows in full
It is a
perennial and possesses a tough rhizome which becomes quite thick and
woody with age and is anchored strongly by its many, tenacious, spreading
roots. Each year the flowering shoots die down, the stems of the next
season arising from buds produced upon the underground rhizome during the
stout, flowering stems, which branch above, reach two or three feet in
height and are clothed with opposite pairs of long, lanceolate, soft downy
leaves which clasp the stem by their bases. The whole the upper part of
the stem and branches is occupied by a handsome spike of reddish-purple
flowers arranged in dense whorls, which are so close together as to give
the illusion of a continuous spike of flowers. A pair of leafy bracts
spreads out from beneath each whorl.
flowers are remarkable, not only for their beauty, but also for the fact
that it was from careful study of this plant by Darwin that it assumed an
important place in this theory of the origin of species.
flowers are remarkable, not only for their beauty, but also for the fact
that it was from careful study of this plant by Darwin that it assumed an
important place in his theory of the origin of species.
flowers possess a cup-shaped calyx-tube from the summit of which six or
seven teeth project. It is usually twelve-ribbed, each rib being covered
with long, upward-pointing hairs. From the top of the calyx-tube arise
five, six or seven spreading, narrow, purple petals which have deep red
veins acting as honey-guides. The twelve stamens spring from the
calyx-tube in two whorls, the stamens of one whorl being longer than those
of the other.
plants one set of stamens is short and the other intermediate in length;
in others one set is intermediate and other is long; whilst in other one
set is long and the other is short.
bottom of the calyx-tube arises the conical ovary, terminated by the style
with its knob-like stigma. Around the base of the ovary is a glandular
ring which secretes nectar.
Corresponding to the three different sets of stamens, we have three
different styles, i.e. short, intermediate and long, but we should also
remark that a short style does not occur in a flower with short stamens,
nor an intermediate style in a flower with intermediate stamens and
similarly in the case of the long style.
plucked three spikes, each of different type, let us carefully examine the
pollen and we shall find that that of the long stamens is large-grained
and green in colour, whilst that of the short stamens is yellow and
small-grained, the medium stamens having pollen of an intermediate type.
bumble-bee visiting a long-styled flower must alight upon the stamens and
style as no other landing stage is offered to it, and on so doing its
hairy abdomen touches the stigma. It then pushes its head into the
flower, brushing the medium stamens with its thorax, whilst its head
touches the short stamens in the calyx-tube. If it now visit’s a
short-styled flowers, its abdomen will be covered with pollen from the
long stamens, its thorax from the medium ones, whilst as it pushes its
head down the calyx-tube, it will touch the stigma hidden within and will
leave upon it pollen from the short stamens of the flower previously
catch one of these bees and examine its under surface, we shall see that
its abdomen is colored green with pollen from long stamens. Its head is
covered with yellow dust, whilst its thorax is greenish-yellow, these
colours corresponding to the different lengths of stamens.
readers who have had the patience to follow me thus far must be wondering
why such a complicated plan has been evolved. Darwin asked himself the
same question over eighty years ago and obtained the answer by careful
experiments. He proved that without insect visitors no seed was set. He
also shoed that in a long-styled flower very little fertile seed was set
if the stigma was pollinated with pollen from short or medium stamens.
Abundant fertile seed was set, however, if the stigma was pollinated with
pollen from long stamens. He obtained similar results in the case of
short and medium styles.
through the peculiar arrangement of the flowers cross-pollination is
practically certain and there is a three to one chance of being arrived
at. We can realize how marvelously insects enter into the flower’s plan
and we can realize the joy of Darwin when his months of careful research
were so amply rewarded.
PLANTS OF THE LOCH FRINGE
varied plants compete with each other for the limited space available in
the shallow waters at the loch’s edge, among them being many tall
shall find the tall, stalwart Cat’s Tail or Reedmace (Typhalatifolia).
This plant, which forms dense masses of stems and leaves on the marshy
edges of many lochs and ponds, has a thick, creeping rhizome giving rise
to erect stems, often over six feet in height, and clothed with many very
long, sheathing, grayish-green leaves.
the height of these plants, the water in which they live is in deep shade,
and hence very few plants can thrive in a colony of Reedmace.
flowers are produced in the well-known club-shaped ‘bullrush’. This is a
huge spike of small flowers, the upper portion of which consists of
stamens, the lower portion of ovaries surrounded by tufts of soft, brown
hair. They are wind pollinated.
plant of this ‘Reed Zone’ is the Erect Bur-reed (Sparganium erectum),
a close relative of the Floating Bur-reed already described. The
rootstock gives rise to long, fleshy runners which creep long distances in
the mud at the bottom of ponds and lakes.
attains two or three feet in height and is covered by long, spreading,
narrow leaves which are triangular in cross section.
wind-pollinated flowers are produced on naked branches in spherical,
sessile inflorescences. The upper consist of male flowers only, the lower
ones of females only.
common inhabitant is the Common Water Plantain (Alisma
Plantago-aquatica). It possesses a very short, corm-like rootstock,
which is rooted in the mud by thick, fleshy roots. From the summit of the
corm buds are produced from which spring the leaves and flowering stalks.
leaves are produced on very long petioles which support the large, ovate,
deep green, smooth blades in the air well above the surface of the water.
midst of the radical leaves arises a tall upright stem often attaining
three feet in height. This develops a complicated and rather beautiful
inflorescence, in the upper part of which whorls of branches are given
off, and from each of them a further whorl is produced, the whole forming
a pyramidal panicle clothed in hundreds of dainty, pale rose flowers.
plant, with its masses of bloom and large, long-stalked leaves, is a quite
distinctive and characteristic plant and cannot be confounded with any
other member of the loch flora.
flower resembles that of the Ranunculus although actually widely separated
from that plant. The calyx is formed by three concave green sepals, the
corolla of three rose-colored petals of a very delicate texture and with a
yellow spot at the base. The ovary resembles that of a Ranunculus very
closely and is surrounded by a ring of stamens. The flowers produce
nectar and are visited by small bees and flies.
species of real Rushes (Juncus) occur on the lake shores, the
Common Rush (Juncus communis) being very abundant. The tall, cylindrical,
smooth, green stems each producing a dense panicle of brown flowers near
the summit are too well know to warrant a close description.
rootstock gives rise to long, creeping runners which produce further tufts
of stems and thus new plants are produced vegetative.
remarkable in possessing no actual leaves, these being reduce to brown
scales at the base of the stems. The brown star-shaped flowers, with
their six ovate, pointed sepals, their three to six stamens and their
three feathery styles, are constructed for wind pollination.
plant is the Hard Rush (Juncus effuses), which may be distinguished
by the deeply channeled glaucous stems of a harder and stiffer texture
than those of the Common Rush. It is almost equally common.
different plant is the Jointed Rush (Juncus articulatus) which has been
divided into several sub-species and varieties. The stems are weak and
spreading and are clothed by sheathing, cylindrical leaves. If these be
dried, they will be seen to have a jointed appearance, as they are divided
internally by cross walls of pith.
flowers are produced in large, terminal panicles and are similar, in
structure, to those of the Common Rush, but always possess six stamens.
It is found on the damp shores of lochs and ponds as well as in marshes
also find the strange little Toad Rush (Juncus bufonius). This
plant is an annual and forms a dense tuft of pale green, weak stems with
several short, cylindrical, radical leaves at their base. The flowers,
which are usually solitary or may be three to four together upon the
branches, are pale green in colour and remarkable for their very pointed
species of Sedges may be found along the lake shores. The Club Rushes (Scirpus)
are conspicuous in forming very large colonies. Each plant has a long,
creeping rootstock giving rise to tufts of upright, cylindrical, green
stems without leaves. The green stems are the photosynthetic organs,
containing chloroplasts, as do the stems of the Common Rush.
wind-pollinated flowers are produced in dense, ovoid heads at the summits
of the stems. They contain three stamens on long slender filaments and
two spreading feathery styles. The genus Scirpus contains a large
number of species which are very similar to one another.
ordinary Sedges (Carex) are well represented and include a vast
number of species which are beyond the scope of this book to describe.
common grasses may be mentioned the Flote-grass (Poa-fluitans)
whose weak stems creep over the mud or float upon the water, the long pale
green leaves being usually floating. The flowers are produced in a long
spike of spike lets each containing eight to twenty flowers.
Common Reed (Arundo Phragmites), a stout perennial often over six
feet high, forming large colonies, may often be met with. The stems are
covered by long, broad leaves resembling those of a Bamboo. The panicles
of flowers are very large and conspicuous, and are composed of hundreds of
purple-brown spike lets. As the seed ripens, it becomes surrounded by a
mass of silky hairs which give the panicle a silvery appearance and act as
parachutes when the seeds are born away upon the autumn gales.