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| Registros recuperados: 36 | |
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| Jacobs, M.. |
| In earlier papers attention was drawn to the fact that virtually all floras neglect the time of fruiting, and it was suggested that filling this gap in our knowledge would make a fine job for many an amateur botanist. The botanists DOING and GADELLA reacted with very elaborate suggestions, thus professionalizing the project and losing sight of the original aim: to get the fruiting times of plants into the floras. It is emphasized here again how much amateurs can contribute if they do not listen to perfectionists. |
| Tipo: Article / Letter to the editor |
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| Ano: 1972 |
URL: http://www.repository.naturalis.nl/record/527953 |
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| Jacobs, M.. |
| Reviewing the conservation situation in Indonesia, we see that concern for animals outweighs that for plants. Sumatra with its richer fauna of large mammals, is better cared for than Borneo with its richer flora*. Too often in the reports, a forest is called a forest, to the neglect of the amazing diversity among the lowland primary rain forests. The absence of botanical expertise beyond the surface is evident throughout, and but occasionally regretted. In view of the great species diversity, and of the fact that this is located in primary vegetations, for animals of nearly all groups as well as for plants, plant conservation clearly comprises at least half the conservationist’s job, in a humid tropical forest region like Malesia. A botanist’s contribution... |
| Tipo: Article / Letter to the editor |
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| Ano: 1977 |
URL: http://www.repository.naturalis.nl/record/532826 |
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| Jacobs, M.. |
| ”Look, these are the modern trees”, Kostermans remarked, pointing to some concrete piles lying near the Forest Research Institute. None of the participants could have missed the sad impression of a moonscape around Kuala Lumpur, which tells of the construction boom in Malaya. ”In Thailand, timber production is nose-diving”, said the Director General of Forestry over the dinner table, ”in the Philippines, nose-diving!” In Malaya, where in the mid-1960’s the government decided to convert the carefully managed forests into oil palm plantation, it has been discovered that no more timber may have been left by the mid-1980’s. So it was none too soon to amass and review the available knowledge on Dipterocarpaceae with an eye on management of the timber resource.... |
| Tipo: Article / Letter to the editor |
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| Ano: 1981 |
URL: http://www.repository.naturalis.nl/record/532952 |
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| Jacobs, M.. |
| Dioecious trees or shrubs. Growth-mode in flushes. Leaves simple, spirally arranged, mostly elliptic to linear, often deciduous. Stipules mostly caducous, sometimes wanting. Catkins terminal, on short, caducous, axillary axes (bearing dwarfed leaves in Mal. spp.). Flowers about spirally arranged along the rhachis of the catkin, each subtended by a membranous, entire bract. Perianth absent. Disk variable in shape, often consisting of 2 median lobules, or only one adaxial (in extra-Mal. spp. rarely more in a whorl, or cupular). Stamens (1-)2-l5, in Malaysian spp. free or nearly so; anthers dehiscing longitudinally. Ovary more or less stipitate, 1-celled, consisting of 2 carpels; style more or less distinct, lobed. Ovules several, anatropous, basal, inserted... |
| Tipo: Article / Letter to the editor |
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| Ano: 1955 |
URL: http://www.repository.naturalis.nl/record/532704 |
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| Jacobs, M.. |
| IUCN, says the paper Categories, Objectives and Criteria for Protected Areas, ”is dedicated to the wise use of the Earth’s natural resources and to the maintenance of the Planet’s natural diversity.” What to think of the sequence? Use first, maintain second? And this comes from the International Union for the Conservation of Nature and Natural Resources? ”The World National Parks Congress, taking place in Bali, Indonesia, October 11-22, 1982, will provide case studies from around the world to illustrate how the various categories of protected areas are meeting the needs of countries of all economic, social, cultural, and political backgrounds,” writes J.A. McNeely, the secretary of the Commission on National Parks and Protected Areas, in a special issue of... |
| Tipo: Article / Letter to the editor |
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| Ano: 1983 |
URL: http://www.repository.naturalis.nl/record/533311 |
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| Jacobs, M.. |
| Herbs or shrubs, often climbing, rarely trees. Indument, if present, consisting of simple (unicellular or multicellular) hairs (sometimes capitate-glandular), stellate hairs, or appendages ( Cleome). Leaves spirally arranged, petioled, simple, palmately dissected, or compound, entire, penninerved, in Stixis pelluciddotted. Stipules thorny, or minute, or wanting. Inflorescences racemose, terminal or lateral, rarely the flowers axillary, or sometimes serial. Bracts, if present, small and caducous, rarely with stipular bracteoles. Flowers bisexual but sometimes the gynoecium reduced (in extra-Mal. spp. staminodes may occur), actinomorphic with a tendency towards zygomorphism, especially in the receptacle and in the position of the petals, mostly in bud until... |
| Tipo: Article / Letter to the editor |
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| Ano: 1960 |
URL: http://www.repository.naturalis.nl/record/532683 |
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| Heel, W.A. van; Jacobs, M.; Bakhuizen van den Brink, R.C.. |
| This study is a full-sounding prelude to the fundamental work on the morphology of inflorescences, which is being prepared by Prof. Dr. W. Troll of Mainz. All inflorescences in Valerianaceae are understood as modifications of one basic form, the thyrse. It is gratifying to note that forms of inflorescences, described in systematical works as for instance 1) capitate or interruptedly spicate (Plectritis), 2) compound dichasium, dichotomous throughout (cymoid Valeriana spp.), or dichotomously branched inflorescence (Valerianella), 3) ‘rispig bis fast trugdoldig’ (Phuodendron), in reality all are variations on one theme, the decussate mono-, to pleiothyrse, i. e. a simple to compound inflorescence with a racemous primary axis and cymous lateral axes. The... |
| Tipo: Article / Letter to the editor |
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| Ano: 1962 |
URL: http://www.repository.naturalis.nl/record/525793 |
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| Jacobs, M.. |
| Allen, Caroline K. (1904-1975) Student of Lauraceae, mainly American but also of SE. Asia and New Guinea, on the Arnold Arboretum staff from 1933 to 1948, later in New York Botanical Garden, where, when the Flora Malesiana in 1968 suddenly was in difficulties, she made considerable efforts to save the project. Obituary Note in J. Arn. Arb. 56 (1975) 264. Bailey, F.M. Australian botanist who in 1879-1915 collected many fungi in Queensland, and wrote a number of papers on them. A list of these and whereabouts of his material given by S.L. Everist & L.J. Alcorn in Taxon 24 (1975) 44. |
| Tipo: Article / Letter to the editor |
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| Ano: 1976 |
URL: http://www.repository.naturalis.nl/record/533280 |
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| Steenis, C.G.G.J. van; Vink, W.; Bakhuizen van den Brink Jr., R.C.; Jacobs, M.. |
| An account of phytochemical substance has been provided by Wiesner’s Rohstoffe des Pflanzenreichs, arranged by products, another account has been given by Karrer, compounds of established constitution arranged according to a chemical system. Though useful, none of these works, including also those of Czapek and Wehmer, aims, however, to use phytochemistry as an auxiliary branch of plant taxonomy. It does seem necessary here to stress in a concise way the importance of the subject for taxonomy. All of us have used some coarse phytochemical characters, looked at characteristic glands and crystals, observed and used colours of dried leaves, tasted plants for bitter substances, sniffed at aromatic oils, and other secondary compounds. The use of these... |
| Tipo: Article / Letter to the editor |
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| Ano: 1963 |
URL: http://www.repository.naturalis.nl/record/525545 |
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| Jacobs, M.. |
| ASHTON, P.S., Crown characteristics of tropical trees. In Tomlinson & Zimmermann (ed.), Tropical Trees as Living Systems (1978) p. 591-615, 8 fig. An important subject in relation to bioproduction. Approaches are through Leaf Area Index (the area of leaf surface above a unit area of ground) and Leaf Area Density (ditto per volume of space). Field work was done in Malaya by students; the simple methods are described. Macaranga gigantea is compared with Musanga cecropioides; other pioneer species are quite different, however. Two profile diagrams of secondary forest are given. Crowns are modified in competition, as reflected in LAI and LAD. Plagiotropic branching allows trees to broaden quickly. Light- or shadepreference is not clearly correlated to... |
| Tipo: Article / Letter to the editor |
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| Ano: 1979 |
URL: http://www.repository.naturalis.nl/record/533254 |
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| Jacobs, M.. |
| According to rough estimate, in these years one quarter of the hardwood in the international timber market comes from Dipterocarpaceae: keruing, meranti are the best-known names. It was a good idea to convene a conference for a review of the available knowledge on this family, which is best represented in Malesia with 380 species. Most of them occur in Borneo, Malaya, Sumatra and the Philippines, in that order. About 35 botanists – too few of them from the region itself – attended the 3-day session, on 14, 15, and 16 June 1977. Organizer was Mme. Géma Maury of Brunoy near Paris, whose work in Malaya on seedlings of the family was mentioned on pages 2565-2566 of the Flora Malesiana Bulletin. Host was Professor J.F. Leroy, Director of the Paris Herbarium.... |
| Tipo: Article / Letter to the editor |
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| Ano: 1977 |
URL: http://www.repository.naturalis.nl/record/533487 |
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| Jacobs, M.. |
| This paper has been composed on the occasion of the retirement of Dr. van Steenis as a professor of botany and director of the Rijksherbarium, Leiden. He was born in 1901, educated at Utrecht, came to Bogor, Indonesia in 1927, settled in Holland in 1950. He founded the Flora Malesiana, and ranks as the greatest authority on the botany of Malesia and adjacent regions. Here are expounded, by his pupil and collaborator, the main subjects and leading ideas in his published works, the most important ones of the latter mentioned. Considered are his work on plant areas, the methodical fact finding by Dr. Van Steenis and Mrs. M. J. van Steenis-Kruseman, his work on the discontinuity among plants forms, on vegetation and ecology, his promotion of the relations... |
| Tipo: Article / Letter to the editor |
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| Ano: 1972 |
URL: http://www.repository.naturalis.nl/record/524818 |
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| Jacobs, M.. |
| This paper complements the revision which before long will appear in the Flora Malesiana, where a key to all species will be given, and descriptions of the Malesian taxa over their whole area; the few non-Malesian taxa are here described. It accounts for the complete synonymy (147 binomials) and typification, with the literature relating to the regions adjacent to Malesia. An Identification List of all examined specimens was separately issued in the Flora Malesiana Lists, number 27 (1966) 430—442; the Herbaria which supplied the materials are: Arnold Arboretum (A), British Museum, Natural History (BM), Bogor (BO), Brisbane (BRI), Cambridge (CGE), Dehra Dun (DD), Gray Herbarium (GH), Kew (K), Leiden (L), Leningrad (LE), Michigan (MICH), Sydney (NSW), Paris... |
| Tipo: Article / Letter to the editor |
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| Ano: 1967 |
URL: http://www.repository.naturalis.nl/record/525452 |
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| Jacobs, M.. |
| Both Nusa Bailing Island and Blambangan Peninsula consist of limestone hills; they are nowadays uninhabited and forest-clad. On Nusa Bailing the forest is mixed and not conspicuously dominated by certain genera. On Blambangan the forest contains much bamboo, which points to ancient human influence, and a number of species characteristic for ‘monsoon-forest’. A few remarks on history, and data about the author’s routes, are given. Most of the plants collected are recorded in sketches of the vegetation. The f. lobata of Gmelina elliptica (Verben.) is reduced. Novelties are not reported, and it is doubtful whether the areas in question deserve much further attention for botanical exploration. |
| Tipo: Article / Letter to the editor |
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| Ano: 1958 |
URL: http://www.repository.naturalis.nl/record/526328 |
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| Jacobs, M.. |
| The preparation of botanical drawings is a craft in its own right, and furthermore, draughtsmen are human beings. Even these simple truths are trodden down by the taxonomist who during a final hour hands the draughtsman a bundle of specimens and some hasty indications. Naturally the result is anguish and confusion. Let us therefore add some observations to improve the situation. First: a botanical artist looks at plants with a different eye from the taxonomist – that’s why he is an artist and not a scientist. Fortunately, some overlap exists, where the two can meet. |
| Tipo: Article / Letter to the editor |
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| Ano: 1977 |
URL: http://www.repository.naturalis.nl/record/532856 |
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| Jacobs, M.. |
| These small structures in nerve axils at the underside of leaves have given food to various theories and have been nonetheless in phytographic and taxonomic neglect almost from the beginning. That was in 1887, when the Swede A.N. Lundstroem published an extensive paper, in which he explained domatia as structures intended to accommodate mites – hence the word acarodomatia – which latter would in turn benefit the plant by cleansing the leaves from fungus spores. Lundstroem arrived at this hypothesis on the strength of ideas current in that time, about the existence of symbiotic relations between ants and plants; it was in the heydays of teleology. A closer investigation left little of the illusions about mutual benefit between ants and plants, but such... |
| Tipo: Article / Letter to the editor |
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| Ano: 1965 |
URL: http://www.repository.naturalis.nl/record/533503 |
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| Jacobs, M.. |
| It is noted with some surprise that in none of the well-known floras of the Netherlands and in general of the floras of Europe and North America, the times of fruiting of the plants are regularly indicated. Knowledge of fruits in general seems to be in a backward state as compared with the attention paid to flowers and their biology. It is remarkable that sometimes chromosome numbers are recorded while such easily observable data as fruiting time are neglected. This omission limits the usefulness of floras, if fruits are wanted for identification, demonstration, or propagation, and if times are to be set for weed control. If flowering and fruiting occur in markedly different periods, the fruiting stage seems seriously under-represented in herbaria. Since... |
| Tipo: Article / Letter to the editor |
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| Ano: 1969 |
URL: http://www.repository.naturalis.nl/record/527795 |
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| Jacobs, M.. |
| Loss of species is the key issue of conservation. Contrary to misuse of land which is visible to anybody with eyes to see, the issue of extinction is sly, treacherous, and open to clear perception only for experts. It touches on quality, and reaches far out in time: hard things to grasp for non-biologists. Thus an extra responsibility devolves on those who are in a position to know and to speak. The value of the genetic resource base has been set forth in e.g. the book by O.H. Frankel & E. Bennett, Genetic resources in plants (1970), and in the BIOTROP symposium edited by J.T. Williams e.a., South East Asian plant genetic resources (1975); Myers adds many striking facts: half the prescriptions in the U.S.A. contain a drug of natural origin. The cardiac... |
| Tipo: Article / Letter to the editor |
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| Ano: 1980 |
URL: http://www.repository.naturalis.nl/record/533059 |
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| Jacobs, M.. |
| Juglandaceae represent a characteristic northern hemisphere family, in the New World going south to Central America (Mexico, Costa Rica, Guatemala, Panama, Cuba, Hispaniola and found S of the equator as fas as c. 30° S, absent from Africa, and overstepping the equator also in the Malaysian region where Engelhardia extends to Java and New Guinea. This distribution shows a remarkable resemblance with that of the Fagaceae-Castaneae which though absent S of the equator in the Americas, occur in Africa in the Mediterranean part only, and though rather well represented as far as New Guinea are also absent in Australia and the Pacific islands. A noteworthy detail of this parallel is that although both are well represented in the Himalayan region and the... |
| Tipo: Article / Letter to the editor |
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| Ano: 1960 |
URL: http://www.repository.naturalis.nl/record/532539 |
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| Registros recuperados: 36 | |
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