Description: Humiria balsamifera (Aublet) St. Hil. var. balsamifera KH 3294, var. guianensis (Benth.) Cuatrecasas KH 2954, 3288, 3313. K: Widespread, but not common, in thickets. S: Northern and southern savannas, savanna scrub and savanna woods. R: Kaieteur savanna (var. guianensis).

Description: Une \xc3\xa9valuation des plantes d\xe2\x80\x99apr\xc3\xa8s leur pouvoir \xc3\xa9dificateur de dunes doit \xc3\xaatre pr\xc3\xa9c\xc3\xa9d\xc3\xa9e d\xe2\x80\x99une description de leur structure a c\xc3\xb4t\xc3\xa9 de l\xe2\x80\x99\xc3\xa9tendue et de la densit\xc3\xa9 des organes a\xc3\xa9riens il faut consid\xc3\xa9rer d\xe2\x80\x99importance capitale et d\xc3\xa9cisive la structure des organes souterrains, tel que K\xc3\x9cHNHOLTZLORDAT (1923) et VAN DIEREN (1934) l\xe2\x80\x99ont sugger\xc3\xa9.\nLes organes souterrains peuvent \xc3\xaatre: des rhizomes, des racines, ou des tiges ensevelies par le sable meuble. Une comparaison des diff\xc3\xa9rentes qualit\xc3\xa9s m\xc3\xa8ne \xc3\xa0 la distinction de groupements et \xc3\xa0 la cr\xc3\xa9ation d\xe2\x80\x99un syst\xc3\xa8me.

Description: The flora of the southern Surinam savannas (not completely known but probably so for the greater part) consists of 314 species collected so far. Ten of these were not found in any other region, 6 belong to the southern Guianan element, 14 to the Guianan element, the rest have a wider distribution. Fourty of the species occur in this region on the northern limit of their area and 18 of these even reach their northernmost station here.\nAmong the 290 species collected on savannas in central Amazonia 82 species were found also on the savannas of southern Surinam.\nNorthern Surinam, with a total of 288 recorded savanna species, has 183 species in common with southern Surinam. This floristic contrast can be correlated for about half of the differentiating species with ecological or geographic factors. The geographic spectra of the two regions are greatly similar.

Description: Up till now the lower deposits of peat (in Dutch: veen-op-groterediepte = peat at greater depth) have been investigated in the Netherlands mainly in the Western part of the country, viz. in the provinces of Noord-Holland, Zuid-Holland and Zeeland. The analyses have shown that the development of this, now comparatively well known peat layer must have begun either in the second half of the boreal period or else in the beginning of the atlantic one, and that it must have come to an end in the first half of the latter. Among the earlier investigators the botanist Mrs VERNEER-LOUMAN and some geologists had arrived at the conclusion that the sudden transgression of the North sea which made an end to the formation of peat, took place in the boreal period, and hat the whole lower deposit of peat, therefore, was of boreal age (lit. 7). This opinion, however, was sufficiently disproved by FLORSCH\xc3\x9cTZ, and all subsequent analyses have confirmed the view that the peat formation must have stopped early in the atlantic period (lit. 2, 3, 4). The same conclusion was arrived at by GODWIN as a result of his investigations of the lower peat found in SE England (lit. 5, 6) and by several German investigators as a result of their analyses of the lower peat, found in NW Germany.\nOnly one analyses of the lower peat in the province of Friesland, in the Northern part of the Netherlands, has sofar been published. The geologist VAN ANDEL found near Kiesterzijl, at a depth of only 3.50 m a thin layer of peat. He identified it with the lower peat from the W part of the Netherlands which occurs several meters deeper. His two diagrams show a boreal age for the basal layers and an atlantic age for the top ones and they confirm therefore the conclusions,obtained in the W part of the country (lit. 1).

Description: At present 38 species of Rhynchospora, now including also Dichromena, are known from Suriname, two of which with two varieties. Two new species are described here: Rh. guianensis and Rh. sublanata. A key to the Suriname species is presented.\nFor every taxon the distribution and, where known, a brief characteristic of its ecology in Suriname are given.

Description: In February and early March, 1961, the senior author spent three weeks on a small savanna in the approximate centre of Suriname, South of Tafelberg, (map 1). He was accompanied by Mr. W. H. A. Hekking. The time was spent in exploring the flora of the savanna and the adjacent forest. As a detailed study of the vegetation of the savannas of northern Suriname was then in progress, several extensive papers being in preparation (Heyligers, 1963; Van Donselaar, 1965; Van Donselaar-Ten Bokkel Huinink, 1966), it was felt that a more thorough inventory of the vegetation and the flora of the savanna might be rewarding. When a general impression of the plant-cover of the area had been obtained, eight representative sample-plots were selected, their vegetation was analyzed and described after the method of the French-Swiss school of phytosociology, and pits were dug in the soil down to bedrock, samples being taken in every distinctive-looking layer. This work was carried out jointly by the senior author and W. H. A. Hekking; part of the floristic exploration was also done by or with Dr. R. M. Tryon, Harvard Herbarium, Cambridge, Mass. The results are here presented. It was felt that in order to integrate them with those obtained elsewhere in Suriname, the collaboration of a specialist familiar with the Suriname savannas in general was required. This was the junior author\xe2\x80\x99s task, who, after his prolonged work on the savannas of northern Suriname, later expanded his work to those of the southern part of the country. The preliminary results of the last-named study are in the press; more detailed field work is in progress as this paper goes to the press.

Description: Geology and soils in general Surinam is situated at the northern edge of the very old and stable Guiana shield. Six-sevenths of the country\xe2\x80\x99s surface are occupied by formations belonging to the shield and designated together as the basal complex. However, the Roraima formation does not belong to the complex. It was deposited during the Mesozoic (probably the Cretaceous) as a thick layer mainly consisting of sandstone that covered the greater part of the shield. Later on the original sandstone plateau was dissected, a process accelerated by the uplifting of the shield, and finally it disappeared almost completely by erosion. The former surface is now only represented by the flat tops of some table-mountains one of which is found in the interior of Surinam: Tafelberg. See Schols & Cohen (1953). The surface of the northern seventh part of the country is occupied by deposits of Quaternary age. In general may be distinguished (from the south to the north): 1) The Zanderij formation, consisting mainly of sands of continental origin; 2) the Coropina formation, comprising the \xe2\x80\x9cold coastal plain\xe2\x80\x9d; the main parts are (a) the so-called \xe2\x80\x9cschols\xe2\x80\x9d, i.e. the remnants of an old sea-clay plain, separated by filled-up tidal gullies, and (b) the remnants of the offshore bars that formerly separated the plain from the sea; 3) the Demerara formation, comprising the \xe2\x80\x9cyoung coastal plain\xe2\x80\x9d. See Van der Eyk (1954, 1957).\nGeological-pedological classification of the savannas Savannas are found on the basal complex, the Roraima, the Zanderij and the Coropina formation. Cohen & Van der Eyk (1953) classify them as follows: I Savannas of the Coropina formation 1. Watamalejo-type \xe2\x80\x93 on the offshore bars 2. Welgelegen-type \xe2\x80\x93 on the \xe2\x80\x9cschols\xe2\x80\x9d II Savannas of the Zanderij formation a. Kasipora-type \xe2\x80\x93 on dry bleached sand soils b. Zanderij-type \xe2\x80\x93 on wet bleached sand soils c. Coesewijne-type \xe2\x80\x93 on non-bleached soils III Savannas of the Roraima formation: Tafelberg-type IV Savannas of the basal complex 1. Paroe-type \xe2\x80\x93 on granitic soils 2. Bosland-type \xe2\x80\x93 on schist hills 3. Saban-pasi-type \xe2\x80\x93 on subgraywacke hills Savanna soils The climate is characterized by the sequence of a long rainy season (April-July), a long dry season (August-November), a short rainy season (December-January) and a short dry season (February-March). In connection with this periodicity the water-table in many places fluctuates strongly in the course of the year. During the dry seasons the upper layers of the savanna soils are always completely dry, except just after a shower. A soil is called very dry if even during the rainy seasons the upper layers are not influenced by the ground water. A very wet soil, however, at this period is covered by some cm of water; in addition it is characterized by many small hummocks, in Surinam called \xe2\x80\x9ckawfoetoes\xe2\x80\x9d, which are built up by worms and in which these animals are able to keep their heads above the water. Certain soils occur that in spite of deep watertables are wet, because an impermeable layer in the subsoil impedes drainage of the topsoil. Of course there is a scala between the extremes \xe2\x80\x9cvery dry\xe2\x80\x9d and \xe2\x80\x9cvery wet\xe2\x80\x9d. The texture of the upper layers ranges from bleached and slightly red sand to sandy and silty clay.\nObject of the investigation The flora and the vegetation of the northern Surinam savannas are the object of this investigation. These savannas do not only represent the types of the Zanderijand the Coropina-formation, but also the Bosland- and the Saban-pasi-type, for these two types are present on the basal complex only near its northern border.\nThe following savannas have been studied. Welgelegen-type: the savannas of Bersaba and Vierkinderen, the Bigi-olo savanna near Hanover and the Fransina savanna near Welgelegen; Kasipora- and Zanderij-type: the white-sandy part of the Lobin savanna near Zanderij; Coesewijne-type: the loamy part of the Lobin savanna, the savanna Mimili Okili near Powaka, the Doti savanna near Wisawini and the Coesewijne savanna near Bigipoika; Saban-pasi-type: the Gros savanna and the De Jong Noord savanna. Data of some other authors pertaining to these and the other types have also been taken into account, some published (Lanjouw, 1936; Maguire c.s., 1948; Heyligers, 1963), some unpublished. The savannas present a marked diversity, among other things with regard to the structure of their vegetation. However, nearly all satisfy this definition: \xe2\x80\x9cA savanna (or a campo) is an area with a xeromorphic vegetation comprising an ecologically dominant ground layer consisting mainly of grasses, sometimes together with sedges, and with or without trees and/or shrubs either forming a more or less continuous layer, or in groups, or isolated.\xe2\x80\x9d The species have been studied with respect to the relation with the habitat, the means of dispersal and the area of distribution, all in mutual correlation. Vegetationunits have been distinguished and classified; ecological and chorologic aspects have been taken into account.\nA combination of all data, obtained during this as well as former investigations by others, permits the drawing of a provisional and general picture of the flora and the vegetation of the northern Surinam savannas as far as the present aspects are concerned.\nThe following statements all apply to N. Surinam only, unless mentioned otherwise.\nFlora Habitat in general. Nearly all plants occurring on the savannas are heliophilous and are able to survive repeated burning. The flora of the open vegetation types consists of about 270 species the majority of which (72 %) is restricted to the open savannas. However, there are species occurring either in other open situations too, partly as weeds (8 %), or on wet savannas and other wet places (3 %), or in savanna rivulets and in swamps (7 %), or in savanna bushes (8 %). Out of ca. 100 species of the savanna bushes only 15 % are restricted to this vegetation type. The other species occur either also in the open savanna (20 %), or along forest borders (8 %), or in savanna wood and forest (23 %) and/or even in rain forest (31 %). A group of 12 % belonging to the last category does not flower or even not grow high in the bushes. Quite apart from this division other groups may be distinguished among the species of the bushes in the following way: occurring also in secondary forest (31 %) in marsh forest (9 %), in swamps (3 %). The trees and shrubs of the savannas support only few epiphytes and (half-) parasites; these belong to 19 different species. In the field nearly all species show some (factual) range with regard to the degree of moistness and the texture of the soil. The texture itself is not necessarily the decisive factor as there is a relation between the texture and some other properties of the soil, e.g. the consistency and the mineral content. This has not been further investigated. The same holds for the species preferring slightly shaded localities. These spots have a microclimate that differs more from that of its surroundings than in light intensity only. The majority of the open-savanna species have diaspores that are not obviously adapted to any agent of dispersal (71 %). The remaining 29 % are distributed over 6 different categories. The diaspores of the species of the bushes belong partly to the non-adapted forms too (35 %), but 50 % of them are fleshy. Generally speaking, the savanna species have a wider geographic distribution than the spieces of the flora of Surinam as a whole. This is particularly true for the opensavanna species.\nOn the basis of similar areas of distribution the species are classed under 6 geographic elements, viz. the Guianan (G), the northern South-American (N), the northern + eastern South-American (NE), the Middle- and northern + eastern South-American (MNE), the South-American (S) and the American element (A). The distribution of the species of the open-savanna vegetations and of the bushes, respectively, among the geographic elements is as follows (percentages): G 12 : 26; N 11: 18; NE 16 : 13; MNE 10 ; 3; S 9 : 18; A 42 : 22. It appears from a comparison of these figures too, that the species of the first group in general have a wider distribution.\nApart from the geographic elements the Roraima element has been distinguished. It comprises all species collected on one or several of the table-mountains in the Guianan interior. The distribution of these species among the geographic elements does not differ considerably from the one of the savanna flora as a whole. It may have appeared already from the foregoing that the species of the bushes, though presenting a higher percentage of adapted diaspores, nevertheless do not have areas of distribution wider than those of the open-savanna species. The expected correlation is, however, apparent if the two groups are considered separately: the mean area of distribution of the species with adapted diaspores is wider than the one of those with non-adapted diaspores. A comparison of the ecological and the chorologic aspects brings to the fore two focal points within the savanna flora: The elements with a small distribution (G and N) are most numerously represented on wet to very wet sandy (in particular white-sandy) soils, whereas the elements with a wide distribution (MNE, S and A) are concentrated on dry and moist non-bleached sands and loams and on very wet soils and present a preference-top on dry and moist loamy sand. The Roraima species are by far the most numerous on the wet white sand, in general they are more numerous on wet than on dry soils.\nVegetation Vegetation-units have been distinguished and classified according to the BraunBlanquel school. It has been attempted to make the groups of so-called characteristic and differential species correspond with ecological groups in the sense of Duvigneaud (1946, 1949). The latter consist of species with clear, sociological affinities between them because of similar habitat requirements.\nThe open-savanna (and orchard-savanna) vegetation-types have been united into a single class which is defined and divided as follows: Class Leptocoryphio-Trachypogonetea. Principal species; Trachypogon plumosus, Leptocoryphium lanatum, Axonopus pulcher and Rhynchospora barbata. It seems likely that this class and its subdivision up to and including the alliances may be applied to the whole of Guiana. 1. Order Trachypogonetalia plumosi. Principal species: Trachypogon plumosus, Axonopus pulcher and Bulbostylis junciformis. On very dry to moist soils. 1.1. Alliance Cassio (ramosae)-Trachypogonion. Principal species: Axonopus pulcher Trachypogon plumosus, and Bulbostylis conifera. On white sands. There are 3 or 4 associations two of which occur on open patches between so-called muri-bushes (see B1). Distribution: Kasipora-type; Guiana and adjoining parts of Brazil. 1.2. Alliance Curatello-Trachypogonion. Among the many tens of species the most common ones are Trachypogon plumosus, Axonopus pulcher, Schizachyrium riedelii and Heliconia psitlacorum. Usually there is a thin layer of trees mainly consisting of Curalella americana, giving the vegetation the aspect of a type of so-called orchard savanna. A rather large part of the species occurs outside the savannas on other open spots too. The alliance occurs on pure reddish and on loamy sands. On the savannas of the Coesewijne- and the Welgelegen-type 5 associations are present. Similar vegetation types are found throughout Guiana, on the central Venezuelan llanos and far into E. Brazil. 1.3. Alliance Rhynchosporo (barbatae) \xe2\x80\x93 Trachvpogonion. Principal species: Axonopus pulcher, Leptocoryphium lanatum, Mesosetum cayennense, Bulbostylis conifera and Rhynchospora barbata var. barbata. On sandy (clay) loam. Two associations on savannas of the Coesewijne-type; they are related to vegetation types in French Guiana and in regions farther to the west, up to the Venezuelan llanos and some of the West Indian Islands. 2. Order Paspaletalia pulchelli. Leptocoryphium lanatum is the only species which is common in all communities of this order. In general the vegetations are not closed. On wet (or even very wet) soils. 2.1. Alliance Syngonantho-Xyridion. Principal species: Paspalum pulchellum, Panicum micranthum, Rhynchospora barbata var. glabra, R. graminea, Xyris guianensis and Abolboda americana. On white sands, wet and very wet. Three associations are found on the savannas of the Zanderij- and the Watamalejo-type. Distribution: Guiana and adjoining parts of Brazil, also on the table-mountains of the Guianan highlands. 2.2. Alliance Bulbostylidion lanatae. Principal species: Trachvpogon plumosus, Paspalum pulchellum, Panicum micranthum, Mesosetum tenuifolium, Rhynchospora barbata var. barbata and R. rhizomatosa. On loamy sand and sandy loam; wet. In northern Surinam 5 associations occur on savannas of the Saban-pasi- and the Watamalejo-type. Distribution: Guiana, probably also on the table-mountains. 2.3. Alliance Imperato (brasiliensis)-Mesosetion (cayennensis). Principal species: Leptocoryphium lanatum, Mesosetum cayennense, Imperata brasiliensis, Rhynchospora barbata var. barbata and R. globosa. On wet sandy loam and heavier soil types. Four associations on savannas of the Coesewijne-, Welgelegen- and Saban-pasi-type. Related vegetation types occur, as far as known, only in regions more to the west, up to the llanos and Guatemala. 3. Order Panicelalia stenodis. Principal species: Leptocoryphium lanatum, Panicum nervosum, Hvpogynium virgatum, Heliconia psittacorum and Tibouchina aspera. On very wet soils, in savanna rivulets and small depressions. There are 2 alliances, both showing relationship with vegetation types occurring in regions more to the west, up to the llanos and some West Indian Islands. 3.1. Alliance Axonopodion chrysitis. Principal species: Leptocorvphium lanatum, Panicum nervosum, Rhynchospora globosa and Tibouchina aspera. On very wet soils of sandy loam and heavier. In N. Surinam 3 associations are found on savannas of the same types as alliance 2.3. 3.2. Alliance Mauritio-Hypogynion (virgati). Principal species: Hypogynium virgatum, Leptocoryphium lanatum, Panicum nervosum, Rhynchospora glauca, Heliconia psittacorum and Tibouchina aspera. Typical are the tall palms of Mauritia flexuosa. The alliance has rather many species in common with the communities of swamps, e.g. Blechnum indicum and Rhynchospora cyperoides. There are 3 associations, found in rivulets and depressions on savannas of all types.\nThe different types of savanna-bushes are merely described. A classification on floristic grounds would be justified only if the savanna woods and forests were included in it too. B1. Ternstroemia-Matayba bushes. See Heyligers (1963). Principal species: Ternstroemia punctata, Clusia fockeana, Licania incana, Humiria balsamifera var. guianensis (\xe2\x80\x9cmuri\xe2\x80\x9d), Pagamea capitata, Matayba opaca and Conomorpha magnoliifolia. On dry white sand. B2. Rapanea bushes. Principal species: Rapanea guianensis, Davilla aspera, Tapirira guianensis, Symplocos guianensis, Miconia rubiginosa, Byrsonima crassifolia, B. coccolobifolia and Curatella americana. On dry loamy sand and dry sandy loam. B3. Cupania bushes. Principal species: Cupania scrobiculata var. frondosa. Byrsonima crassifolia, Davilla aspera, Miconia ciliata, Maprounea guianensis, Symplocos guianensis Protium heptaphyllum, and Curatella americana. On moist loamy sand and moist sandy loam. B4. Clusia-Scleria bushes. See Heyligers (1963). Principal species: Licania incana, Clusia fockeana, Bactris campestris and Scleria pyramidalis. On wet white sand. B5. Marlierea bushes. Principal species: Marlierea montana, Bactris campestris and Licania incana. On wet loamy sand. B6. Roupala-Antonia bushes. Principal species: Roupala montana, Antonia ovata, Davilla aspera, Miconia ciliata, Bactris campestris, Licania incana, Humiria balsamifera div. var., Pagamea guianensis and Marlierea montana. On knolls of pebbles embedded in sandy loam; wet.\nExistence, origin and maintenance of the savannas There is no type of climate that accounts for a savanna vegetation irrespective of other conditions. However, a climate that permits the existence of savanna vegetations may be called a \xe2\x80\x9csavanna climate\xe2\x80\x9d. The latter is characterized by a certain difference between the precipitation in dry and wet seasons, independent of absolute values. The climate of northern Surinam is a savanna climate in this sense. A savanna vegetation is natural, i.e. determined edaphically, if the upper layer of the soil is alternately desiccated and saturated with water, thus in general in wet and very wet localities and in rivulets. As far as known the following savanna types and vegetation types are involved in this situation (the rivulets left out of consideration): Watamalejo (2.1) Welgelegen, partly (2.2), Zanderij (2.1 and B4), Saban-pasi (2.1 and B5, 2.2. and B6) and Bosland (?). A savanna vegetation occurs in dry localities only if fires prevent the formation of a closed layer of trees or shrubs. This is found among the following types: Welgelegen, partly (1.2 and 1.3), Coesewijne (1.2 and B2, 1.3 and B3) and Kasipora (1.1 and B1). Parts of the savannas of the Welgelegen-, Coesewijne- and Saban-pasi-type occupied now by vegetations of the Imperato-Mesosetion (2.3) and the Axonopodion chrysitis (3.1) would probably be overgrown very slowly by the surrounding forest and only starting from its edges if the fires were stopped. It might be easily assumed that savannas owing their maintenance at present only to deliberate burning, originated from forests as a result of human interference as well. However, the possibility may not be excluded that they came into existence very long ago, either caused by natural fires or in consequence of a water economy of the soil differing from the present one.\nFinal conclusions All available data concerning the flora and the vegetation of the northern Surinam savannas justify the following theories: The wet white-sand savannas of the Zanderij-type have vegetation types (2.1) consisting of species that mainly stem from formerly or still existing savannas on the basal complex and on the Roraima formation, probably chiefly on the latter. These species may have reached the Zanderij formation either directly by means of series of savannas in the interior that still may have been present during the break-down of the Roraima plateau, or indirectly by the way of other sandy regions bordering the edges of the Guiana shield. The vegetations of the savannas belonging to the Saban-pasi-type on wet loamy sand and sandy loam (2.2) consist of species which already for a long time were common to the basal complex and the Roraima plateau or/and which originated from the plateau, and besides of species that developed on the basal complex or migrated from elsewhere to the subgraywacke-area. The savannas of the Watamalejo-type and of the Welgelegen-type N. of the Wane-creek have a flora that may be regarded as a selection from that of the two preceding types. The vegetation types on dry and moist, red, pure and loamy sands belonging to the Coesewijne- and the Welgelegen-type (1.2) have a high percentage of their species in common with the campos of central and eastern Brazil. It seems possible that these species came to N. Surinam from the campos. The species combination of the savanna vegetations from other habitats does not permit a conclusion with regard to their possible origin.

Description: The vegetation was studied of a number of savannas in northern and southern Surinam, and in French Guiana. The results are compared in particular with the vegetation classification proposed earlier for northern Surinam, and with some records from the northern Rupununi Savanna, Guyana (Van Donselaar 1965). The savannas studied near Brownsweg (northern Surinam) have vegetation types that correspond completely with those of some other savannas of the same geological-pedological type more to the North, as described before. New is the finding of a type of scrub bordering the savanna, being the scrub equivalent of a type of bushes described earlier as the Marlierea type. On the top and the slopes of the Blauwe Berg near Berg en Dal (northern Surinam) an anthropogenic savanna has developed. Two new vegetation types are recorded here that belong to the alliance Rhynchosporo-Trachypogonion. At the foot of the hill a flat savanna supports a vegetation that gives the impression of being of recent origin and unbalanced. It appears possible to apply the existing classification to the communities found on savannas near Cayenne (French Guiana). In this area the conspicuous Byrsonima verbascifolia (var. villosa fo. spathulata) occurs in several undescribed vegetation types that belong to various entities. A xerophilous and a hygrophilous community of Byrsonima verbascifolia are distinguished, belonging to the Rhynchosporo-Trachypogonion and the Bulbostylidion lanatae, respectively.\nOn the Sipaliwini Savanna in southern Surinam most vegetation types do not fit into one of the existing alliances. However, if new alliances would be described, it should be possible to include them into the existing orders. There probably is an alliance, called here \xe2\x80\x9ccommunities of Trachypogon plumosus and Bulbostylis spadicea\xe2\x80\x9d, that might be regarded as the southern counterpart of the Rhynchosporo-Trachypogonion in the order Trachypogonetalia plumosi, and a supposed alliance with much Rhynchospora graminea and R. globosa might have the same position with regard to the Imperato-Mesosetion in the order Paspaletalia pulchelli. Among the communities that might be included in the alliance Axonopodion chrysitidis there is one occurring on sandy soil without a hog-wallow structure at the surface. Floristically it has connections with the Paspaletalia pulchelli but it also has many characteristic species of its own. Whether this community has to be placed in a distinct alliance will have to depend on the results of further investigations in this area. Anyhow, more data are needed for the drafting of a complete picture of the rich and interesting Sipaliwini Savanna. On a savanna south-west of the airstrip \xe2\x80\x9cSipaliwini\xe2\x80\x9d (southern Surinam) the vegetation consists mainly of communities belonging to the Bulbostylidion lanatae.\nSummarizing the above-mentioned results, one may say that a number of communities not studied before are added to the picture of the savanna vegetation of the Guianas. It proved possible to integrate these communities without much difficulty in the classification presented earlier that so far has functioned as a practical framework.

Description: This study deals with the vegetation of about 125 former beds of the larger rivers in the Netherlands. It includes all communities of higher plants except the carrs, which are dealt with in a separate paper by Kop (1961). The investigation of the communities aimed at a knowledge of their floristic composition as well as at a definition of their habitat. The description and the classification of the units was carried out according to the concepts and methods of the Braun-Blanquet school (Braun-Blanquet, 1932, 1951; Becking, 1957). Moreover, among the former river beds types were recognized, characterized by a special set of communities and by correlated abiotical properties. A number of vegetation-units are described here for the first time, viz. The Polygoneto-Nymphoidetum (alliance Potamion) with the subass. typicum and the subass. potametosum pectinati. According to descriptions of vegetations found in the literature the subass. typicum is also present in former river beds of the Rhine in Germany about up to Bingen (LAUTERBRON, 1917); more to the south it is replaced by the Trapo-Nymphoidetum (OBERDORFER, 1957). The Sparganieto-Glycerietum fluitantis polygonetosum (alliance Glycerieto-Sparganion). The main difference with the habitat of the other subassociations (see MAAS, 1959), where the water is moving either permanently (brooks) or at least now and then (ditches), is that the vegetation is influenced by the current only during the shortlasting annual floods. The Cicuteto-Caricetum pseudocyperus (alliance Phragmition) is to be divided into two subassociations, viz. the subass. typicum and the subass. comaretosum. The main difference between the habitats of the two subassociations appears to be that the first is eutrophic and the second more mesotrophic. The Scirpetum triquetri et maritimi typhetosum (alliance Phragmition). In contrast with the other subassociations (see ZONNEVELD, 1960), this one occurs only in oligoto mesohalinic, stagnant water. The Caricetum elatae (alliance Magnocaricion) is revised. Carex hudsonii is the only characteristic species found throughout the area in which the association occurs. The community everywhere participates in the hydrosere on sand or peat. The following subdivision was made: Subass. typicum; the community is eutraphentous; according to the literature it is found in Switzerland (KOCH, 1926), S. Germany (OBERDORFER, 1957) and Belgium (LEBRUN c.s., 1949; VANDEN BERGHEN, 1952 a). Subass. comaretosum: more mesotraphentous than the subass. typicum; found in N. Germany (T\xc3\x9cXEN, 1937; PASSARGE, 1955 b) and the Netherlands. Of the Valerianeto-Filipenduletum (alliance Filipendulo-Petasition) two new subassocaitions are established, viz.: Subass. juncetosum; it is the replacing-community of a mesotraphentous variant of the Alnetum glutinosae. Subass. senecietosum; represented in the river forelands outside the tidal area; it replaces there an eutraphentous Salicion-community, and may be natural if the development of trees is prevented by ice-drift. Eight types of former river beds were distinguished. Two of these could be subdivided into some subtypes. Their classification according to their communities and their abiotical properties is summarized in table 26. Descriptions of habitats which more or less resemble one of these types of former river beds, are known from other parts of the Netherlands and from the adjoining parts of Germany and Belgium. However, as far as we know, of the types described by us, viz. those represented in the river forelands along the upper courses of the rivers, seem to differ from all habitats that have been described so far.

Description: Dans la v\xc3\xa9g\xc3\xa9tation des dunes du Languedoc J. BRAUN-BLANQUET (1952) distingue trois associations, \xc3\xa0 savoir; 1) l\xe2\x80\x99Agropyretum mediterraneum parmi et sur les premi\xc3\xa8res dunes basses; 2) l\xe2\x80\x99Ammophiletum arundinaceae sur les dunes plus hautes; et 3) le Crucianelletum maritimae dans les d\xc3\xa9pressions et en arri\xc3\xa8re des dunes. Or, il est \xc3\xa9tabli que le d\xc3\xa9veloppement de la premi\xc3\xa8re association et le passage de celle-ci \xc3\xa0 la deuxi\xc3\xa8me sont accompagn\xc3\xa9s d\xe2\x80\x99une \xc3\xa9dification de dunes, et que la troisi\xc3\xa8me provient de la d\xc3\xa9g\xc3\xa9n\xc3\xa9rescence de la deuxi\xc3\xa8me.\nK\xc3\x9cHNHOLTZ-LORDAT (1923) a le premier attir\xc3\xa9 l\xe2\x80\x99attention sur le r\xc3\xb4le essentiel jou\xc3\xa9 par la v\xc3\xa9g\xc3\xa9tation dans l\xe2\x80\x99\xc3\xa9dification des dunes du Languedoc. Les r\xc3\xa9sultats de ses recherches ont \xc3\xa9t\xc3\xa9 confirm\xc3\xa9s par VAN DIEREN (1934) aux Pays-Bas. Les deux auteurs ont \xc3\xa9tudi\xc3\xa9 le pouvoir accumulateur du sable par les parties a\xc3\xa9riennes des plantes; mais le premier seul donne aussi quelques indications sur le r\xc3\xb4le \xc3\xa9dificateur des parties souterraines.