THE WATER HYACINTH. 
not included in the same order as the true Hyacinth, which belongs to | the 
Liliacew, a large order comprising plants such as the Lily, true Hyacinth, Tulip, 
Asparagus, Onion, and Aloe. It derives its name chiefly from the resemblance 
of the simple spike of six to twelve flowers of a pale-purple colour to that of 
the true Hyacinth, but differs in being an aquatic plant. Its flowers are borne 
ona short stiff stem 6 to 12 inches long with several sheathery bracts at the 
base. (See Plate.) The upper petal is larger than the other five, and is: 
marked by a yellow spot in a cloud of blue. The leaves are somewhat rounded, 
but very variable. Their stalks are just as variable in length, and the lower 
half is inflated, more especially in the young leaves. These swellings, which 
are filled with air and act as floats for the whole plant, gradually disappear as 
the leaves become older, until the stems become nearly equal in thickness through- 
out, or taper from the base to the leaf blade. The leaves form a rosette from 
1 to 2 feet high, and this remains above the water as the plant floats. The 
roots hang freely in the water, or attach themselves to the mud in the more 
shallow water of water-courses and lakes. The roots may penetrate to a depth 
of 2 to 4 feet, but the plant may thrive just as well in fairly deep water. The 
plant flowers freely, producing abundance of seed, which ripens and falls between 
the leaves of the parent plant, and, coming in contact with the water, 
soon germinates. As the older plants mature they are gradually forced below 
the surface of the water by the younger generation, and an ever-increasing 
thickness of matted vegetation is produced. The amount of air in the cellular 
tissue of the floats is often sufliciently buoyant to enable one to walk about on 
the surface of a mass of weed as if on a raft. In shallow water-courses and in 
lagoons it is only a matter of a few years until they are filled up with a mass of 
decomposing vegetable matter. Besides its propagation by a profuse develop- 
ment of seed there is normally a propagation by stolons, which in tropical waters 
is very rapid and effective. Stolons branch out from an old stem, extend from 
4 to 8 inches from the parent plant, and form on their ends a little rosette of 
leaves. Roots spring from the node where the rosette is formed, and the young 
plant soon becomes self-supporting. Old plants will usually be found to have 
formed several (three to five, or more) stolons which branch out in different 
directions. Several generations of plants produced in this way will frequently be 
found connected by the old stolons, which are often about half-an-inch in diameter, 
and are very strong. As plants commonly grow close together, the newly deve- 
loped offshoots bind the mass firmly together, so that it is difficult to separate 
the individual plants. It thus forms compact masses which frequently cover 
acres of waterways and lagoons, blocking navigation. Boats, punts, droghers, 
and small steamers often find it impossible to penetrate such growths. 
Distribution. 
The historical accounts of its introduction into various centres where it is 
now a serious pest are very much a repetition of one another. The plant is an 
attractive one with its green bulbous leaves and its handsome pale-lavender 
flowers, and is frequently grown in green-houses, or in the home in a pot of 
water. It is from such apparently innocent sources that it soon becomes spread 
round the neighbouring water-courses and ponds. In a U.S.A. Bulletin, Bureau 
of Plant Industry, No. 18, Dr. Webber gives an interesting account of its 
‘introduction into the St. John’s River, Florida, in 1890. It was grown in a 
pond, which was afterwards cleaned out, and the material thrown into the river 
near by, and thence it spread to all the lower streams. In many cases this was 
aided by admirers of the plant, who had no idea of its possible spread and 
damage. They placed plants in the river near their own homes to beautify the 
surroundings. In 1894 it was so plentiful as to attract the serious attention of 
steam boatmen and fishermen, and after severe storms and floods in the same 
year it was found to be very abundant. Similar is the story of its introduction 
to the northern rivers of New South Wales. About twenty years ago a resident 
of Swan Creek, 4 miles below Grafton, purchased a specimen in Brisbane, and 
later on threw it into the creek near by. It thrived so well that in two years it 
took possession of the creek, which there is 50 yards wide, and from 10 to 35 
feet deep. 
It killed out the blue flowered water lily, Nymphwa stellata, which used to 
exist there in great abundance. ; 
At the present time it is to be found growing luxuriantly on the Clarence and 
Richmond Rivers and their tributaries, and also in smaller quantities on the 
Tweed and Macleay. 
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