ALBERT

Description: 1. Samples of benthic invertebrate fauna were collected in – a ditch, situated in a protected area in the peaty area near the Maarsseveense plassen (prov. Utrecht), – four ditches in the neighbourhood of Castricum (N-Holland), not far from the dune district, – two ditches with water of a high chloride-content on Texel (N- Holland). 2. The faunistic results, with the additional information of some physical and chemical data on the different sampling points, made it possible to draw some conclusions concerning – the importance of the factor salinity for a faunistically oriented typology of ditches, – the importance of the group Hydracarina for a classification of ditch-biocenoses, – the influence of artificial current, caused by the inlet of water, on the invertebrate fauna of ditches and on the faunistical evaluation of the pollution-level in ditches.

Description: A new catfish, Glyptothorax stocki, belonging to the family Sisoridae, is described and figured. The new species from Pakistan and Azad Kashmir is compared with Glyptothorax platypogonoides from Sumatra, with which it was confused.

Description: The Scrophulariaceae, though chiefly a family of herbaceous plants, contain also a number of genera with trees ( Paulownia and Wightia) and genera with species of suffruticose and fruticose habit.\nMy colleague Mr. A. M. Cleef, who is studying the vegetation of the high Andean parts of Colombia collected material of the small genus Aragoa, endemic in the paramos of the Colombian and Venezuelan Andes. Though this genus consists in the main of small broomlike shrubs, a new species, Aragoa perez-arbelaeziana Romero, discovered by him, is a small tree, of which the stem reaches a diameter of 8 cm. The wood of Aragoa of which the structure was so far unknown, proved to be noteworthy because of the complete absence of rays and parenchyma. There was no indication at all of growth rings, and the vessels can not be distinguished from the fibres as seen on a cross section, as both are of equal width. In longitudinal sections vessels become recognizable by their simple perforations, their spiral thickenings and the presence of a few simple pits; whereas the fibre tracheids lack the spiral thickenings, and possess numerous bordered pits on both the radial and tangential walls. The diameter of the vessels and fibres varies in the 5 species investigated by me between 16 and 24 \xce\xbcm; the length of the vessel members is on the average 260 (185-370) \xce\xbcm and that of the fibre tracheids 310 (220-450) \xce\xbcm. This unusual wood structure was found not only in the small stems with a diameter of 4-8 mm, but also in the stem of the only arboreous species.

Description: By means of modernized sieving techniques 110 m3 of matrix from a gully filling in the Tegelen Clay were sieved. This yielded a good collection of small mammals, which clarifies the stratigraphic position of the Tiglian, a collection of other vertebrates, a small collection of mollusks, and a vast amount of plant material. A good collection of mollusks was made through classical collecting techniques. The faunal lists in this paper constitute a considerable enlargement of the known Tegelen fauna. Collecting is continuing, and further additions to the fauna may be expected.

Description: Some details are given on the bryophyte vegetation in an old clay pit near Venlo. Due to burrowing activities, the bottom of the pit has a very broken surface, and in the upper soil layer sand, sandy clay and pure clay (from the Tiglien formation) replace each other. On some places water comes out of the soil. Some locally important bryophyte unions (in the sense of Barkman 1973) are described. An impoverished form of the Haplomitrium- Fossombronia incurva union occurs on moist sandy ground. On a steep, south-exposed, dry clay edge a fragment of the Aloinetum rigidae was found. The wet clayey parts are occupied by a vegetation mainly consisting of Leiocolea badensis and Anisothecium varium, for which a new union is proposed, the Leiocolea badensis- Anisothecium varium union. On a steep sandy side the rare species Anisothecium rufescens, Mniobryum lutescens and Trichodon cylindricus were found; the last two species have not been reported from the Netherlands before. In conclusion, the importance of such clay pits in general and this one in particular as refugia for bryophyte flora and vegation is stressed.

Description: J. T. R. KALKHOVEN, A. H. P. STUMPEL en S. E. STUMPEL-RIENKS, Landelijke Milieukartering; een landschapsecologische kartering van het natuurlijk milieu in Nederland ten behoeve van de ruimtelijke planning op nationaal niveau. Studierapport Rijksplanologische Dienst no. 8. Staatsuitgeverij, \xe2\x80\x99s-Gravenhage, 1976 (verspreid juni 1977), 141 pag. + 4 bijlagen, \xc6\x92 35,\xe2\x80\x94 (Ook verschenen als Verhandeling 9 van het Rijksinstituut voor Natuurbeheer, Leersum).

Description: Leptochloa fascicularis (Lamk.) A. Gray [Diplachne fascicularis (Lamk.) P.B.] has been found as an alien in the Netherlands. The author gives a key to the species of the genus in addition to that in Flora Neerlandica.

Description: A. J. QUEN\xc3\x89-BOTERENBROOD & J. MENNEMA, Zeldzame Nederlandse plantesoorten in Zuid-Holland. Provinciale Waterstaat Zuid-Holland, \xe2\x80\x99s-Gravenhage, 1973, 110 pag., 31 verspreidingskaarten en 4 figuren, fl. 5,\xe2\x80\x94.\nGemeentelijke, provinciale en landelijke overheid tonen zich de laatste jaren in toenemende mate belangstellend voor nauwkeurige gegevens over \xe2\x80\x9ehet milieu\xe2\x80\x9d. Het is uitermate verheugend dat de Provinciale Waterstaat van Zuid-Holland voor een serieus wetenschappelijk onderzoek niet alleen belangstelling heeft, maar het ook in alle opzichten stimuleert. De resultaten van het onderzoek naar de verspreiding van zeldzame planten, met name in Zuid-Holland, zijn neergelegd in vijf bijlagen, waarvan de tweede de belangrijkste is. Deze bijlage omvat 31 verspreidingskaarten van Nederlandse plantesoorten en is hiermee te beschouwen als de voorloper van de nu spoedig te verwachten Atlas van de Nederlandse Flora. De verspreidingskaarten zijn samengesteld op grond van IVON-hoklijsten, herbariummateriaal en literatuuropgaven en gesplitst in gegevens die dateren van v\xc3\xb3\xc3\xb3r en van n\xc3\xa1 1950, zodat bovendien de achteruitgang resp. vooruitgang van de betreflende soort snel kan worden afgelezen. De begeleidende tekst van elke kaart geeft aan deze een extra dimensie, niet in de laatste plaats door de verantwoording en documentatie van de niet-opgenomen gegevens, die in bijna alle tot dusverre verschenen atlassen over de verspreiding van planten in Europa ontbreken. Ik geloof stellig dat deze wijze van presentatie zeer de voorkeur verdient en dat het bezwaar van de lange duur der voorbereiding van zulke kaarten hierdoor ruimschoots wordt goedgemaakt.

Description: Small, locally dominant plants of Juncus effusus f. pauciflorus have been collected in the exceptionally warm and dry summer of 1976 on the dry bottom of a wide ditch in the Southwestern part of the country near Roosendaal (prov. of N.-Brabant). Earlier such forms were known in the Netherlands from four localities. All the summers of the years in which these forms had been found were characterised metereologically as \xe2\x80\x9e(very) hot\xe2\x80\x9d as well as \xe2\x80\x9e(very) dry\xe2\x80\x9d, which is very unusual in this country. The individual plants have normal terete stems, sometimes with young \xe2\x80\x98lateral\xe2\x80\x99 inflorescences, as well as small, filiform stems bearing apicallya few fruits and with the lower sheaths terminating in distinct linear blades; fruits of the latter are usually not retuse at the apex, and contain apparently normal seeds ( fig. 1). Ontogenetical research on the unusual dimorphism of this form is required.

Description: In Senecio jacobaea L. two forms with non-radiating capitules are distinguished: a.) a non-heritable form, hence of no systematic value, occurring incidentally throughout the area of the species, with the outer ray of fruits nearly glabrous like in normal radiating forms of the species, and b.) a heritable (DE VRIES, 1901) form with a distinct area (fig. 1) with all fruits equally hairy (probably by reduction of the outer ray of flowers). The distribution of the latter form, provisionally called Senecio jacobaea var. nudus Weston (Bot. Univ. 3, 1772, p. 641; syn.: S. jacobaea var. floseulosus Lamk. et DC.; S. dunensis Dum.), is given from herbarium material and literature; var. nudus fully replaces the type variety in the dunes in the Netherlands southwards to IJmuiden, only in the dunes between IJmuiden and Den Haag both the radiating form and var. nudus are found together (at present the latter is very common whereas the radiating form is rare, but at the end of the last century this situation was reverse). Var. nudus may be worth the rank of subspecies. A probable hybrid S. aquaticus X jacobaea var. nudus is recorded from the island of Terschelling.