( 54 ) 



either floating or submerged, and only these may fairly be said to derive their nutriment 

 from the water in which they vegetote. 



But as the water is the element which effects the growth of such plants, I shall make in 

 future no distinction between these two modes of attachment, but treat them simultaneously. 



Many of the water plants are amphibious, i. c, they grow both in water and on land, 

 and consequently often change tiieir habits. Such amphibious plants afford ample material 

 for those who desire to study the variations of plants. 



As a first division of the aquatic formation I shall take the vegetation, peculiar to sweet 

 waters, in contradistinction to those of braokish and seawaters. The brackish waters cause 

 to a certain degree a transition of the fresh water vegetation into the tidal vegetation. 



12. Sweet-uatef-veyetation, 



The vegetation of the fresh or sweet waters might be divided into vegetation 



a. of swamps. 



b. of lakes and other stagnant waters, and, 



c. of running waters, such as rivers, etc. 



The first named connect, as already mentioned, the land and water vegetation. 



a. Vegetation of swamps, etc. True swamps and morasses in India should be only 

 such as are inundated also during the dry season, those that dry up are rather low inundated 

 lauds which have already been treated under 10 h. Sometimes Phragmites ItoxburghiL, .and 

 another species, form a sort of jungle in shallow swamps that are destitute or nearly so of 

 other grasses. They more often, however, consist of low grasses and water plants, almost 

 identical with those of the low moist pastures. These are Hymenachne interrupta, and my- 

 urus, Paspa/um scrobiculatum, Anosporum cephalotes, Cyperus pallidus and other species, 

 Panicum crus galli, and colonum, Leersia hexandra, and sometimes also wild rice. Ipomoca 

 replans is almost everywhere a companion of the above grasses, along with several species of 

 Fimbristylis, &nd Eleocharis, Ludwiyicijmrvi/lora, Jussiaea repens and sujfruticom, Hygrorhiza 

 aridata, Ocnanthe stolonifera, Rungia repens, Marsilea erosa, Commelyna coinmunis, Centrostachys 

 aquatica, Sesbania paludosa, Aeschynomene Indica, Nepmnia olemcea, Sagittaria sagittifolia, 

 ButQtnus lanceolatus, Monochoria hastata, Cyanotis axillaris, Floscopa paniculata, Lasia aculeata, 

 Enhydra Jluctuans, Eriocaulon, Hygrophila salicifolia and longifolia, Dysop/iylla verticillata, 

 several species of Uiricularia, a small creeping Hydrolea and similar water plants. 



Lower Algae and Diatoms are chiefly found amongst the floating roots and branches of 

 these water plants, and a few Zygnemaceae, especially the common species of Spiroyyra, 

 cover the ground. Often enough, however, the water remains quite clear. 



b. Vegetation of lakes and other stagnant waters. Mountain lakes are very rare in Burma 

 but a few are to be found in the Martaban hills. Those in Pegu are mostly alluvial 

 lakes, often of a very doubtful character. In the diluvial zone several lakes are met with, 

 of which perhaps the one near liangoon is the largest. The low land lakes are very numer- 

 ous indeed ; some of them are rather large ; the greater part, however, form only small 

 expanses, sometimes not larger than a middle sized tank. 



If they possess muddy water, as is often the case in the Irrawaddi alluvium, especially 

 in the tracts of savannah forests, little is seen of water plants, and even Diatoms are very 

 scarce. But if the water is of a clearer quality, a profusion of water plants, fixed as well 

 as floating, inhabit the lakes. 



Attached to the ground we find a species or two of Nitella in abundance ; also further 

 Ceratophyllum tuberculatum, Myriophyllum, Nymjihaea Lotus, and sometimes stcllata, Ne- 

 lumbo niicifera locally, Blyxa, Villarsia cristata, and Indica, Aponogeton monostachyum, Najas 

 minor, Hydrilla verticillata, Nechamandra alternifolia, Vallisneria spiralis, Ottelia aliinoides, 

 Sagittaria, etc. Further Uiricularia flexuosa, diantha, and 2 or 3 other species, Neptunia olei-acea, 

 Ipomoea reptans, Jussiaea repens, Hygrorhiza aristata. Of floating plants the following 

 deserve special mention : Pistta stratiotes, Sakinia cucullata and natans, Azolla pinnata, 

 Lemna paucicostata, polyrrhiza and tenera, Wolfia arrhiza, 2 or 3 species of Riccia, etc. 



Algae are found plentiful in such clear lakes, especially when they are of small size, 

 floating as well as attached to the water plants. Amongst the labyrinth of these plants 

 numerous Diatoms can be collected, and beautiful forms of Dc.smidieae, of which especially 

 Closterium, Cosmarium, Pediastrum and similar genera are very rich in species. 



Such shallow lakes, when in sunny open localities, are often covered by a green, and 

 not seldom also by a brick-coloured scum which, on microscopical examination, turns 

 out to be no Alga at all, but animalculse (chiefly Euglena viridis and sanguinea). 

 They often also occupy the swamps, above referred to, and develope themselves there 

 80 prodigiously that (especially the brick-coloured species,) they form sheets of coloured 

 matter of several hundred square feet, which entirely hides from view tiie water beneath, 

 and attracts the attention even from a distance of several miles. 



