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| Registros recuperados: 31 | |
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| Ham, R.W.J.M. van der; Verloove, Filip. |
| *Nationaal Herbarium Nederland / Leiden branch, Postbus 9514, 2300 RA Leiden; e-mail: ham@nhn.leidenuniv.nl **Laboratorium Vaatplanten, Departement Biologie, Universiteit Gent, K.L. Ledeganckstraat 35, B 9000 Gent, België Ter voorbereiding van een beschouwing over het voorkomen in steden van de ‘lage landen’ van soorten uit het varengeslacht Adiantum (Venushaar), willen wij hier een beknopt overzicht geven van een aantal recente vondsten, en daaraan de oproep verbinden om eventuele aanvullingen door te geven. |
| Tipo: Article / Letter to the editor |
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| Ano: 2002 |
URL: http://www.repository.naturalis.nl/record/527040 |
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| Ham, R.W.J.M. van der. |
| The aim of this book is stated as “to introduce the minute and mysterious world of pollen to as many readers as possible” and “to re-establish the morphological study of pollen taking into account newly accumulated phylogenetic information”. It provides introductory accounts on ontogeny, pollen morphology, pollination, pollen physiology, genetics of pollen, airborne pollen and pollinosis, and pollen analysis. Technically speaking it is a well-produced book, being bound in hard covers and neatly printed on good paper. Moreover, it is overwhelmingly illustrated. However, when looking and reading carefully through the book one gets a bit disappointed. Let us first consider the illustrations, which take up at least three quarters of the book. In general, the... |
| Tipo: Article / Letter to the editor |
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| Ano: 1989 |
URL: http://www.repository.naturalis.nl/record/525049 |
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| Ham, R.W.J.M. van der; Heuven, B.J. van. |
| A pollen morphological survey of the genus Guioa is presented. Based on a study of the harmomegathy in relation to morphological series, evolutionary trends are postulated: 1. wide ectoapertures → narrow ectoapertures 2. grain parasyncolporate → grain colporate 3. grain parasyncolporate → grain syncolporate 4. ornamentation rugulate → ornamentation psilate-imperforate. It is suggested that the most ‘primitive’ species of Guioa occur in the southeastern part of the distribution area of the genus. Guioa can be subdivided into four poorly delimited pollen morphological groups. Its affinities to other genera in the Cupanieae are briefly discussed. Pollen of the most ‘primitive’ group is similar to that of several ‘primitive’ genera (e.g. Arytera, Matayba,... |
| Tipo: Article / Letter to the editor |
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| Ano: 1989 |
URL: http://www.repository.naturalis.nl/record/525415 |
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| Ham, R.W.J.M. van der; Meijden, Ruud van der. |
| In the last years isolated specimens of Daphne laureola have been found in three localities in the Netherlands: one in the dunes of Voorne, and two in public gardens in Delft. Daphne laureola is only rarely cultivated in the Netherlands. It is argued that the Dutch localities might belong to a more or less natural extension of the distribution area of this species, which might be associated with the still ameliorating climatic conditions for atlantic-mediterranean species in the Netherlands. |
| Tipo: Article / Letter to the editor |
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| Ano: 2001 |
URL: http://www.repository.naturalis.nl/record/526810 |
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| Ham, R.W.J.M. van der. |
| Consequently upon a revision of Mischocarpus (Van der Ham, 1977a), a detailed study has been made of several characters in Arytera in order to get a better understanding of the delimitation of the two genera mutually. The differences between Mischocarpus and Arytera given by Radlkofer (1931) in his key are vague and can only be used when fruiting material is available. However, several species in Arytera were described by him and others on flowering material only. Two species of Mischocarpus could be connected with species of Arytera. One species of Arytera appeared to be the same as Mischocarpus exangulatus. M. exangulatus has, besides typical Mischocarpus characters, several features unique in Mischocarpus but more regularly occurring in Arytera.... |
| Tipo: Article / Letter to the editor |
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| Ano: 1977 |
URL: http://www.repository.naturalis.nl/record/525431 |
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| Adema, F.; Ham, R.W.J.M. van der; Hartog, C. den; Ploeg, D.T.E. van der; Weeda, E.J.. |
| Een nieuwe desinfectiemethode voor herbaria. Droog organisch materiaal oefent een grote aantrekkingskracht uit op allerlei dierlijke organismen. Gedroogde planten, het herbarium, maken daarop geen uitzondering en worden met graagte door verschillende insektesoorten gegeten. Vooral de z.g. museumkevers worden nogal eens in collecties aangetroffen. Iedereen, die er een herbarium op na houdt, weet, dat regelmatige controle en desinfectie van zijn collectie noodzakelijk zijn. Het controleren van vele, soms duizenden of tienduizenden, exemplaren is een tijdrovend, zij het niet altijd onplezierig karweitje. Het desinfecteren van een collectie kan echter wel onplezierig zijn. Om een herbarium insektenvrij te houden, wordt tot nu toe gewerkt met bepaalde... |
| Tipo: Article / Letter to the editor |
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| Ano: 1980 |
URL: http://www.repository.naturalis.nl/record/528088 |
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| Ham, R.W.J.M. van der. |
| The occurrence of Teucrium chamaedrys subsp. chamaedrys in the Netherlands is discussed. Since 1905 this subspecies has been present in one locality in the dunes south-west of Haarlem. Probably it was imported there with pheasant fodder. The plants maintain themselves easily but seem to be unable to make ripe seeds. As this subspecies has not yet spread, it is not included in the flora of the Netherlands. |
| Tipo: Article / Letter to the editor |
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| Ano: 1981 |
URL: http://www.repository.naturalis.nl/record/526886 |
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| Ham, R.W.J.M. van der. |
| During a revision of herbarium material of the genus Barbarea, it became apparent that Barbarea intermedia Bor. is much more common in the Netherlands than was supposed. It is probably a native rather than a casual species although it may have been introduced long ago. Barbarea verna (Mill.) Aschrs., usually thought of as a rare native species, appears to be merely a casual in the Netherlands. |
| Tipo: Article / Letter to the editor |
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| Ano: 1982 |
URL: http://www.repository.naturalis.nl/record/526952 |
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| Ham, R.W.J.M. van der. |
| A pollen-morphological survey of all four genera of the Stemonaceae at the light and electron microscope level is presented. Stemonaceae is a eurypalynous family. Stichoneuron pollen, up to now described as monosulcate, appears to be inaperturate. Pentastemona pollen is most deviating in Stemonaceae. Its sexine consists of elements that resemble Ubisch bodies very much. It shares several features with pollen of Peliosanthes (Convallariaceae) and Trillium (Trilliaceae). However, the closest relatives of Pentastemona could not be traced with the available pollen-morphological evidence. |
| Tipo: Article / Letter to the editor |
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| Ano: 1991 |
URL: http://www.repository.naturalis.nl/record/526247 |
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| Ham, R.W.J.M. van der. |
| The pollen morphology of all 11 species of the genus Mischocarpus is studied. All species possess basically the same syntricolpate pollen type. Transitions to the tricolpate type were observed rarely. Within the syntricolpate type, subtypes could be established. For a few species a rather wide range of variability in some characters is described. Pollen morphology correlates with macromorphology as well as with geography, thus supporting the results, based on macromorphological evidence, concerning infrageneric structure and relationships of Mischocarpus. |
| Tipo: Article / Letter to the editor |
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| Ano: 1977 |
URL: http://www.repository.naturalis.nl/record/525111 |
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| Adema, F.; Ham, R.W.J.M. van der. |
| Cladistic analyses of pollen-morphological, leaf-anatomical and macromorphological data of Jagera, Trigonachras, and several new species lead to the conclusion that a new genus, Cnesmocarpon, has to be described (see the Taxonomic Part on p. 195). Two pollen types are described, one including Cnesmocarpon, the other including Jagera and Trigonachras. The morphologies of these pollen types suggest different harmomegathic systems: nonapertural and apertural folding respectively. The ornamentation of Cnesmocarpon pollen resembles that of several other Cupanieae genera. The scabrate ornamentation of Jagera and Trigonachras pollen, often provided with hair-like appendages, is unique in that tribe. Leaf-anatomically Jagera is characterised by the presence of... |
| Tipo: Article / Letter to the editor |
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| Ano: 1993 |
URL: http://www.repository.naturalis.nl/record/526125 |
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| Ham, R.W.J.M. van der. |
| This book contains the proceedings of the special tapetum symposium, held during the VIII International Palynological Congress in 1992 (Aix-en-Provence, France). Twelve contributions demonstrate the importance of the tapetum in the reproduction of land plants. As the editors state: any tapetum malfunction causes pollen sterility. All papers deal with basic research, not with applied research such as plant breeding and genetic engineering. Although ‘evolution’ is listed in the title, very little (no special contribution) is devoted to this subject. It is a pity, because a phylogenetic theory has been suggested in the past, which should be treated in a book covering such a highly and diversely specialised structure. A taxonomic survey (table) listing the... |
| Tipo: Article / Letter to the editor |
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| Ano: 1994 |
URL: http://www.repository.naturalis.nl/record/525715 |
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| Ham, R.W.J.M. van der; Heel, W.A. van. |
| Secondary pollen presentation is a taxonomically widespread phenomenon that is unknown to many botanists. As defined by the author, it embraces those cases in which pollen is transferred within the flower, and presented to pollinators on or by floral structures other than the thecae. The intraflower transfer often involves intriguing adaptations of petals, androecium and distal parts of the gynoecium. The present book is largely a case of secondary presentation itself, being actually a review of the literature on the subject, supplemented with unpublished data and drawings. The main part (208 pp.) extensively describes familywise all taxa known to have secondary pollen presentation, with many comments inserted. Papaveraceae, Leguminosae, Proteaceae,... |
| Tipo: Article / Letter to the editor |
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| Ano: 1994 |
URL: http://www.repository.naturalis.nl/record/525231 |
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| Ham, R.W.J.M. van der. |
| Mischocarpus Blume, Bijdr. (1825) 238, nom. cons.; Rumphia 3 (1849) 166; Radlk., Pfl. R. Heft 98 (1933) 1288—1310. — Cupania § Mischocarpus Miq., Fl. Ind. Bat. I, 2 (1859) 566. — Type: M. sundaicus Bl. Pedicellia Lour., Fl. Coch. (1790) 655, nom. rejic. (see under dubious names). — Type: P. oppositifolia Lour. Mischocodon Radlk., Bot. jahrb. 50 (1913) 79; Pfl. R. Heft 98 (1933) 1327—1328. — Type: M. reticulatus Radlk. Shrubs or, sometimes large, trees, sometimes with a slender unbranched stem. Buttresses sometimes present (M. largifolius). Indumentum rather dense to sometimes very sparse, consisting of mostly appressed, short to long, brownish to ferruginous hairs; no glandular scales. Twigs brownish to reddish-brown to greyish. Axillary buds just above... |
| Tipo: Article / Letter to the editor |
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| Ano: 1977 |
URL: http://www.repository.naturalis.nl/record/524863 |
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| Welzen, P.C. van; Ham, R.W.J.M. van der; Heel, W.A. van; Uffelen, G.A. van; Wilde, W.J.J.O. de; Kalkman, C.; Valkenburg, Johan L.C.H. van. |
| This project of the Royal Botanic Garden Edinburgh aims to provide regional manuals and on-line identification computer programs to the timber species of Dipterocarpaceae. The Singapore manual is a first trial, later editions should include other islands in the Malay Archipelago. The possibility is also offered to have tailor-made manuals for specific regions against cost price. Many data have been gathered, especially vegetative characters one can readily observe while standing underneath these enormous trees. In this respect the database will be very useful, because due to the very irregular flowering of the Dipterocarpaceae, flowers and fruits are usually unavailable, and even if they are present, they are found high in the tree. |
| Tipo: Article / Letter to the editor |
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| Ano: 1996 |
URL: http://www.repository.naturalis.nl/record/525707 |
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| Ham, R.W.J.M. van der. |
| Induced by too many wrongly determined specimens of Lactuca virosa L. the author discusses a number of differences with Lactuca serriola L. The fruit especially offers reliable characters (fig. 3). L. virosa probably occurs only as an alien in the Netherlands. In recent years L. serriola had a considerable expansion, particularly in the urbanized west of the country. Very often it concerns f. integrifolia Bogenhard. Nowadays, this forma seems to be more common than in former years. |
| Tipo: Article / Letter to the editor |
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| Ano: 1981 |
URL: http://www.repository.naturalis.nl/record/527578 |
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| Registros recuperados: 31 | |
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