The new water weed ?Anacharis alsinastrum, some account of it /by William Marshall.

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ANACHARIS ALSINASTRUM,

A NEW WATER WEED.

(2EPRINTED FROM THE CAMBRIDGE INDEPENDENT PRESS.)

REVISED BY THE AUTHOR.

LETTER.—No. L
Sir,

A remarkable plant has recently made its appearance in
the rivers Ouse and Cam, and already abounds to such a
degree, as not only to impede navigation, but what is of far
more importance in this fen country, threatens to injure our
drainage. :

It occurs in dense tangled submerged masses of consider-
able extent, and is so heavy, that when cut, (instead of rising
to the surface and floating down to sea, like other weeds)
_ it sinks to the bottom. It is this property which is likely
to make it injurious to drainage. The intruder is so unlike
any other water plant, that it may be at once recognized by
its leaves growing in threes, round a slender stringy stem.
The watermen on the river have already named it “ Water
Thyme,” from a faint general resemblance which it bears to
that plant.

That it is new to our rivers here, is certain; watermen and
fishermen pronounce it to be, (as I heard one of them call it
the other day), “ a furreigner.” ;

A

+

om

Who the stranger is, whence he came, and how he got
here, are questions of considerable scientific interest ; but by
what means he is to be got rid of, is the practical question.
With your permission I will discuss these points in another
communication.

Yours obediently,

Ely, August 11, 1852. W. MARSHALL.

P.S.—As I am anxious to know how far the plant has
spread itself through the rivers of the Eastern Counties, if
any of your readers residing in the Middle Level, or on the
banks of any of the tributaries of the Ouse, would favour
me with their experience, I should be greatly obliged.

No. II.
Sir,

IT now trouble you with the second part of my communi-
cation on the subject of this new . Water Weed, in which I
promised to discuss, who the stranger is—whence he came—
how he got here—and, by what means he is to be got rid of ?

With respect to the first question it is sufficient to say,
that it is the “ Anacharis Alsinastrum” of your eminent
townsman, Mr. C. C. Basineron (to whose accurate labors
our indigenous botany is so much indebted), who so named ~
it in 1848.

The following is a short account of what we know of the
plant:— | :

It appears that it was first found in this country on the
3rd August, 1842, by Dr. Grorcr J OHNSTON, of Berwick-

on-Tweed, in the lake of Dunse Castle, in Berwickshire.

The lake is situated upon a tributary of the Whiteadder
River, which flows into the Tweed. Specimens were sent
at the time to Mr. BaBincton; but the discovery was lost

5°
sight of, and the interest in it died away until the Autumn
of 1847, when it was again discovered by Miss Kirpy, of
Lubbenham Lodge, in reservoirs adjoining the Foxton Locks,
on the Canal near Market Harborough, in Leicestershire.
The plants were all females, and were found in considerable
abundance, growing “ closely matted together.” Miss Kirpy
had not observed it there before, and the reservoirs had been
cleaned out two years previously.

Miss Kirpy’s rediscovery awakened the attention of
Botanists to the subject, and Mr. BaBincron published a
description of the plant in the “ Annals of Natural History,”
for February, 1848. Dr. Jounsron, the first discoverer, on
reading Mr. Banineron’s account, at once recognized it as
the plant he had found in the Loch of Dunse Castle, and in
the following Autumn found the plant in two stations in the
Whiteadder River.

_. The same season, but later, it was found by Mr. JAmEs
MiTcHEL, in Nottinghamshire, in the Lene, (a tributary of
the Trent) near Nottingham, “ growing in great profusion
for about a quarter of a mile in extent.” In November, of
the same year, it was found in Northamptonshire, in the
Watford Locks, by Mr. Kirn, “ very abundant.” The
Watford Locks are on the same line of Canal as the Foxton
reservoirs. Mr, Kirx observed that when water was drawn
from either of the Locks, the force of the current detached
small sprigs of the Anacharis, which were carried into the
body of the Canal. Mr. Krrx considered it to be an intro-
_ duced plant. His plants were also all females. Subsequently,
Mr. Kirk changed his views, and regarded the plant, “ from
its simultaneous discovery in so many other localities,” as a
true native. He also described it as growing in such dense
masses, that it was with difficulty good sized specimens could
be detached, owing to its extreme brittleness. Mr. Kirk
was informed by the Lock-man that the plant was quite as

6

abundant when he first came to the Locks, five years before,
although the reservoirs had been cleaned out once or twice
during that period. The Lock-man further stated, that he ~
had formerly resided at the Foxton Locks, and that the
reservoirs there, were “ full of it more than twenty years
back,” also that it had been plentiful in the Market Har-
borough Canal, during the whole of that period. A short
time after this conversation took place, two labourers belong-
ing to the Locks came up, and both of them confirmed the
statement of its being plentiful in the Market Harborough
Canal, and one of them added: that the “ Welford Branch,”
a narrow Canal, comparatively little used, was so full of it,
that “ the passage of boats was impeded, and the Canal
necessitated to be cleared out once or twice a year, and that
it had been so for many years.” I apprehend however, there
must be some mistake here.

In August, 1849, it was found in Derbyshire and Stafford-
shire, by Mr. Epwin Brown, growing “ in profusion,” in
the Trent, near Burton-on-Trent, and also in the Canal
there. Mr. Brown was convinced that the plant was new
to that locality. He describes it as forming “ very large
submerged masses, of a striking appearance.” All the flowers
were females. In Christmas, 1850, it was found by Mr. Kirk
in Warwickshire, near Rugby, “ in the greatest abundance ;”
and in July, 1851, by the same gentleman, in the Oxford
Canal near Wyken Colliery.

The Rey. W. M. Hinp, writing from Burton-on-Trent, in
J uly, 1851, describes the plant as occupying a much larger
portion of the river than when first noticed, eighteen months
before, and adds: “in fact, it bids fair in a short time to
block up one of the two streams into which the Trent here

Last year (1851), the Anacharis was noticed by myself
and others in the river at Ely, but not in great quantities.

7

This year it has increased so much that the river may be
said to be full of it; but I must defer a more particular
account of its behaviour in the Cam and Ouse till next week,
when, if space permit, I will dispose of the remaining ques-
tions of whence it came, how it got here, and by what: means
it is to be got rid of.
Yours obediently, :
Ely, August 18, 1852. W. MARSHALL.

No. III.
Sir,

Having in my last, traced this plant from its first discovery
in Berwickshire in 1842, down to its recent appearance in
the Cam and Ouse, I propose to devote this letter to a par-
ticular account of its behaviour in our own rivers, believing
the chief interest connected with it, to lie in this direction.

I have already described the Weed as growing in dense
submerged masses, distinguishable at once from all others
by its “leaves growing in threes round a slender stringy
stem ;” and although this brief description is amply suffi-
cient to identify the troublesome pest, a short further account
of its appearance and habits may not be uninteresting. The
colour of the plant is a deep green; the leaves are about half
an inch long, by an eighth wide, egg-shaped at the point,
and beset with minute teeth, which cause them to cling. The
stems are very brittle, so that whenever the plant is disturbed,
fragments are broken off. Although, at present, it cannot
propagate itself by seed, its powers of increase are pro-
digious, as every fragment is capable of becoming an
independent plant, producing roots and stems, and extending
itself indefinitely in every direction. Most of our water
plants require, in order to their increase, to be rooted in the
bottom or sides of the river or drain in which they are *

8

found ; but this is independent altogether of that condition,

and actually grows as it travels slowly down the stream, after

»

being cut. The specific gravity of it is so nearly that of
water, that it is more disposed to sink than float, and the cut
masses may be seen under water, either on or near the
bottom, rolling over and over like woolpacks, clinging to

. every thing they meet with, and accumulating in great

quantities at locks and bridges (hugging the piers of the
latter), and grounding in shoal water. Its mode of growth
may be best seen in still and narrow waters, (such as the
stream above the mills at Cambridge), where it seems to
spring first from the two sides and bottom, meeting at length
in the middle, and completely filling up the watercourse, as
I have seen-in some cases, almost to the exclusion of the
water. Except in very quiet places it is not likely to be
found in flower. I have, however, found it flowering in great
profusion just below Ely ; but as the plant is diecious, (i.e.
producing male and female flowers on separate individuals),
there is no fear, as I have before remarked, of its producing
seeds in this country, all the specimens hitherto found being
of one sex only,

Although there is little doubt that in 1850, and, perhaps
in 1849, it might have been detected in our rivers, if dili-
gently sought for, it does not appear to have attracted the
notice of Watermen and the staff of Fen Officials, whose

when it was noticed in considerable quantities all the way
from Small Bridges down to Bottisham Lock, but not to

: ger to be sought for, it may be
found everywhere, in more or less quantity, from Cambridge
downwards, choking up the mouths of docks, sluices, and

9

narrow watercourses, and in the upper portions of the river,
impeding both navigation and drainage. Perhaps its won-
derful and rapid increase this year may be owing to the
excess of wet, and the long continuance of hot weather
raising the temperature of the water to an unusual degree ;
but if it should continue to increase in anything like the
same ratio as it has done, the upper parts of our rivers will
no longer be able to pass their waters to sea, and the Navi-
- gation Interest may surrender to the Railways what little
remains to them of the carrying trade.

That it is already a source of annoyance to our Watermen
is evident by the universal complaints which have been made
of the obstructed state of the River Cam. I am told that the
river at the backs of the Colleges has been so blocked, that
extra horses had to be yoked on, before barges could be got
up to Fosters’ Mills.

Sluiceheepers also complain that masses of it get into the
pen, and when the slackers are drawn, the openings are
choked, and the operation of letting boats through is greatly
impeded.

The Railway Dock at Ely, became so choked with the
weed that boats could not enter until several tons of it had
been lifted out. At Roswell Hill Pits, below Ely, the
entrance docking was blocked, so that the gault boats could
not get in till it was removed. (It was here where I found
it in flower).

Rowers, too, find it interferes with their amusements; and
Swimmers remark, that it clings to them like “ scratchweed,”
and that if they are overtaken by a lump of it, they are
likely to be entangled and dragged by it into deep water.*

Even the Fishermen complain that they can no longer ply
their nets so freely as they were wont; and 1 am informed,

correspondent of the Cambridge Chronicle remarks, that the weed will
upset a “ funny” first, and then prevent the rower from swimming to land,

10

on good authority, that they have discontinued setting their —
hook-lines, (7. e. lines laid across the river with a series of
hooks attached), because the “‘ new weed” either carries them
away bodily, or strips them both of their baits and fish.*

Lastly, the Drainage is impeded. Mr. Human, Sen., our
experienced officer, informs me that although the waters this
season have been run off at Denver Sluice a foot lower than
in previous years, the average height of the water in the
river below Cambridge has been a foot higher than in ordi-
nary seasons; and he refers at least half this difference to the
obstructions occasioned by the presence of the “ Anacharis.”

From these facts I apprehend your readers will by this
time have arrived at the conclusion that a troublesome stran-
ger has intruded himself among us, uninvited, but, whence
he came—how he got here—and by what means he is to be got
rid of—will furnish ample materials for another letter.

Yours obediently,
Ely, August 24th, 1852. W. MARSHALL.

No. IV.
Sir,

If you were some fine morning to find that a strange
person, of foreign aspect had intruded himself into your
house, I imagine the questions which would most naturally
occur to your mind under such circumstances would be:
whence came the fellow—how did he get here—and how am
I to get rid of him? But as no one is presumed to know
the faces of all his neighbours, you would wish, doubtless,
before accosting him as an “ impertinent foreigner,” to make
sure he was not some obscure native of one of the back

* The Rev. A. Bioxam informs me that a ke alah 4 with
the last few years, has been such as entirely to prevent the ne yee ee
wvent the
Trent, between Repton, and Castle Donnington, MONS | “he

| :

ll

streets of your own town. So in the case of our present
unwelcome visitor, before one can ask the question—whence
he came? we ought to be satisfied that he really is a stranger.
Now, some botanists seem to think that he has all along .
been a native of these islands, but has “ made himself so
scarce” as not to have been previously recognized by our

- Botanical Detective Force ;* while others pronounce him an

unmistakeable foreigner—greedy and rapacious, “ fixin”
himself in John Bull’s rivers for all the world as if he had as
good a right to occupy them as the aborigines themselves.
For my own part I have no sort of doubt upon the subject:
I hold with the watermen that he is a veritable ‘ foreigner,”
although I find that the Rev. Mr. BLoxam, who had visited
its place of growth, said in 1848, “ he could find no reason
to doubt its being a true native ;” and Mr. Kir, who first
regarded it as introduced, afterwards changed his views, and
concluded it must be indigenous, “ from its simultaneous
appearance in so many localities.”t Whatever Mr. BLoxam’s
reasons were for his opinion, Mr. BaBINGTON appears to
have agreed with him at that time. If, however, Mr. BLoxam
thought so, only because “ numbers of other water-plants
grew in the same locality,” the reasoning is very unsatis-
factory, seeing that any introduced water-plant must necessa-
rily be found in company with other water-plants. The
other argument derived from its “ simultaneous appearance
in so many localities,” loses much of its force, when the
numerous localities come to be reduced, as I shall hereafter
shew, to one, or at most two. I have already stated that the

_ plant was 8 first found in 1842, in the Lock at Dunse Castle,

* The plant is so unlike any of gl British water-plants, that it could not
possibly have oe ih overlooked. There is but one plant, the “ Potamogeton
densum,” that could ever be mistaken for i . and this only by the most super-

er.

I have since ascertained that Mr. BLoxam’s “ opinion has long been chan-
ged as regards its eing a native,” but that Mr. Kirk still “ most decidedly
considers it indigenou

12

Now at first sight one would suppose a quiet Lake in Scot-
- land beyond the reach of sophistication ; but Dr. Jonnston
informs me that aquatic plants have been introduced into that
piece of water from the south. Were then we have evidence
of the probability of the Anacharis being an introduced plant
at Dunse. Then we learn that, six years after, it was found
in the Whiteadder, between the Lock at Dunse and the sea;
and now in August, 1852, Dr. JoHNnsTon writes to me thus:
* As with you, so with us, the weed is altering the character
of the Whiteadder, and will require before long to be dealt
with as we have dealt with savages in some places.” Its
second discovery was in the Foxton Locks, situate on the
Union Canal, which connects Market Harborough with
Leicester, and the river Welland with the Soar and (through
the Soar) with the Trent. When therefore it was found in
the Lene, near Nottingham, it should be remembered that
it was in a part of the same water system, Afterwards, it
was found in the Locks at Welford and Watford, near
Northampton; but these points are within a very short
distance of each other, and both are on the same line of canal
as the Foxton Reservoir. In 1849, it was found in the canal
near Burton-on-Trent, and in the Trent River; but these
points, although in two new counties, were all in water com-
munication with the previous stations ; and again,.when it was
found ins Warwickshire, near Rugby, and in the Oxford
canal, these are within ten or twelve miles of the Watford
Station, and on the same line of canal. These several Midland
localities may therefore be regarded virtually as but one,
because the Anacharis, when once introduced, would, in a
few years, inoculate any connected water system from one
end to the other.*
ri

* Ido not deem it necessary to refer to the Sussex and Yorkshire stations,

— it is admitted that in these places the weed has certainly been intro-

13

Indeed, if any one will take the trouble to look at a good
map of England, it will appear clear that there was hardly
a spot so well calculated as a centre from which to inoculate
our English rivers, as Rugby or the Watford Locks, near
the Crick Railway Station. From such a point, situate at
an altitude above the sea of about 350-feet, and very nearly
at the line of watershed which divides England into the
River Basins of the Severn on the west; the Trent on the
“north; the Ouse on the east; and the Thames on the south;
a few detached sprigs travelling different ways, would enter
the Severn through the Avon via Rugby and Warwick; the
Thames, through the Cherwell at Banbury, and thence by
Oxford; the Nene, above Northampton ; the Ouse at Buck-
ingham; the Welland, at Market Harborough; the Trent,
above Burton, by the Anker and Tame; and again, lower
down at Nottingham by the Soar; and from Nottingham
the Witham could be reached by the Grantham canal, and
from thence by Lincoln, the Drains of North Lincolnshire
would be impregnated. And then, when the pest had tra-
velled as far down (on the Trent, for example) as the top of
the Humber), the numerous vessels ascending the Great
Valley of 4,000 square miles, drained by the Yorkshire
Ouse, would carry it up with them, and so inoculate that
ample river and its numerous tributaries.

That the plant is only now descending these rivers is evident,
It has appeared in the upper part of the Ouse, and for four
years has been observed in the Nene; two years ago it
appeared at Lincoln, but had not then reached the northern
parts of that country, and in our own river, while it occupies
the line of descent from Cambridge to the sea, the * Old
West” river and the “ Lark” are, as yet, free of it, except
just above their confluences, Looking at these facts, I would
ask, if it be a native, how is it that it has never exhibited
its extraordinary powers of increase till now? For if it be

14

not new, we must suppose that a new property has recently
been imparted to it, which is absurd; and what better proof
of its newness can be offered than by the facts made patent,
that it is only now in the act of descending our rivers. To
my mind, the evidence is conclusive that it is a foreign
importation, and it is only when we are satisfied on that point -
that we can properly discuss the question of whence came it?

Now this is a point on which no ex cathedra dictum can at
present be pronounced. The question can only be settled by
a careful comparison of our plant with its congeners in other
countries. It appears, however, that plants of the genus
** Anacharis” are confined to the American continent, and
- that one plant, called “ Anacharis Nuttalli,” or Udora
Canadensis,” very closely resembling, if not identical with
ours, is found in the American rivers. Dr. J OHNSTON has
specimens from Dr. Maciacan, gathered in Detroit River,
which exactly resembled his Berwickshire plant, save only
a slight difference in the outline of the leaves.

The American plant is frequent in the rivers from Canada
to Virginia. I think, therefore, we may safely answer the
question of “ whence it came,” by saying, “ From North
~ America.” *

But, then, how did he get here? Now there are various
ways in which a plant may be imported. A Botanist, in the
ardour of that Botanical instinct which prompts him to
surround himself with as many as possible of the beautiful
and varied forms of vegetable life, might have introduced it ;
but we have no evidence that such has been the case, although
Botanists have been known to do such things. If one might
hazard a conjecture, I should say that it was most likely
introduced at or about Rugby, with American timber, during
Gi? ial ae de,

as it does not a that it is found in Norway, or indeed anywhere in
Northern Europe, I cannot subscribe to his assertion,

15

the execution of some of the numerous railways which meet
at that point. We know that in North America the timber
is floated in rafts down the rivers, in which case fragments of
the American weed would cling to it, or seeds might find
their way into the clefts of the wood, and if dut one seed, or
one fragment retained its vitality, in some moist cranny, till it
reached its final destination, I verily believe it would be
sufficient to account for the myriads of individuals that now
exist in England. Indeed, from the circumstance of all the
plants hitherto found being of one sex, the hypothesis of its
propagation from a single seed or fragment is rendered more
probable than by supposing a number of seeds or fragments
to have been imported.

But some one will be asking, as the plant could not have
found its way by water from Rugby or Watford to Cam-
bridge, how came it in the Cam? This question through the
kindness of Mr. Basineton, I am enabled to answer dis-
tinctly. In 1847, a specimen from the Foxton Locks was
planted in a tub in the Cambridge Botanical Garden, and in
1848, the late Mr. Murray, the curator, placed a piece of
it in the Conduit stream, that passes by the new garden. In
the following year, on Mr. Banineton asking what had
become of the stick which marked the site of the plant, he
was informed that it had spread all over the ditch. From
this point it doubtless escaped by the waste pipe across the
Trumpington Road, into the ¢ Vicar’s Brook,” and from
thence into the river, above the Mills, where it is now found
in the greatest profusion. In the case of the Cam, then, we
see it proved to demonstration that the short space of four
years has been sufficient for one small piece of the * Anacharis”
to multiply so as to impede both navigation and drainage.
When Proressor Gray, of Boston, U.S., was at Cam-
bridge, Mr. BABINGTON mentioned the circumstances to him,
at which he expressed surprise, as the Anacharis is not found

- hope of its finding its way to sea; but be raked out at once
-. upon the shores; and Commissioners of Drainage should

16

to spread in this active manner in America. Bebe our
sluggish streams, the ‘decomposing vegetable and animal
matters in our Cambridge waters, and especially the excess
of lime present, (15 to 17 grains in the gallon), furnishing
an inexhaustable supply of inorganic food, may account for
its more rapid increase here than in America.

Lastly: with respect to the question,— How is it to be got
rid of ? I think we may answer it at once by an emphatic
“NoT aT ALL.” Like the imported European horses and
oxen in the South American Pampas, or Capt. Coox’s pigs
in New Zealand, or the Norway rat in our own farm yards,
or the Oriental black beetle in London kitchens, or (more
remarkable still) like the exotic mollusk (the Dreissena
Polymorpha), which has now spread itself through the canals
of this country, we may conclude it has fairly established
itself amongst us, never to be eradicated. All we shall be
able to do is to try and keep it down, and in order to effect q
this, it should not be left in the rivers after being cut, in the

beware of letting fresh water into their districts, for the weed
will inevitably enter with it, and blockade the ditches.
In conclusion, Mr. Editor, you must allow me to remark —
(while warmly thanking you for your courtesy in affording
‘mae so much space in your valuable journal), that I should
- never have obtruded myself on the public if I did not re-
cognize in the introduction of this “ New Water Weed”
_ beyond the mere scientific question, considerations of much
local and economical importance to this Fen country.
oe Yours obediently,
Ely, August 30th, 1852. W. MARSHALL.

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