BLUMEA 21 (1973) I—Bo1 —80 A revision of DigitariaHaller (Gramineae) in Malesia. Notes on Malesian grasses VI J.F. Veldkamp Rijksherbarium, Leiden '...a material stronger than armor: Crabgrass' Parker & The is (B. J. Hart, King a Fink, 1964) Contents Summary 1 General introduction 2 Part 1. General observations Nomenclature A. 4 B. Taxonomic position 6 C. Morphology 7 D. Infra-generic taxonomy 12 E. Infra-specific taxonomy and genetics 17 F. Cultivated species 19 G. References 19 Part II. Descriptive part of data A. Presentation 22 B. Guide to the key and descriptions 22 c. Key 23 D. Descriptions 27 E. dubiae vel excludendae Species 71 Index 74 Summary Inthis revision is of the Malesian paper a given species ofthe Crabgrasses, or Digitaria Haller ( Gramineae). The research was done at the Rijksherbarium, Leyden, while many other Herbaria were shortly visited; some field work was done in Indonesia, Australia, and Papua-New Guinea. the in The foundation for study this large and cosmopolitan genus must be Henrard’s monumental work of the which therefore cited ‘Monograph genus Digitaria’ (1950), is extensively and discussed. in in the the Henrard based his division sections, 32 subgenus Digitaria, with anemphasis on amount of and the various of but such subdivision spikelets per grouplet types hairs, a appears difficult to maintain. As in only part of the species of Digitaria occurs Malesia, not representing all sections, a new infra-generic can be As far as the sections Malesia system not given. present in are concerned, it appeared that the Biformes, Horizontales, and Parviglumaehad to be united with the section Digitaria, the Remotae and Subeffusae had to into be merged one, the Remotae, while the Atrofuscae had to be included, at least partly, in the Clavipilae, here renamed is Filiformes. The subgenus Solitaria better regarded as a section of the subgenus Digitaria. The distinction between annual and in the these perennial everwet tropics poses a problem; conceptions have been but defined maintained, on a more clearly basis. In the region studied 27 species occur, 3 of which are new to science; 25 species are indigenous, 2 are introduced and in the have been taken established; key 4 more species up, which were introduced only once, and but have probably vanished. One subspecies one variety are distinguished, both under a new name. All also studied for their extra-Malcsian from it taxa were distribution; the resulting synonymy appeared 1 BLUMEA VOL. No. 2 XXI, I, 1973 that about Henrard could be reduced The is estimated to contain 52 species recognized by to 24. genus about 170 species instead of about 325. said in Finally, some species are discussed which were either to occur Malesia or to belong to Digitaria, but for which one or the other of these suggestions proved to be false. Of these taxa two species and one while variety were given a new name, one new variety could be described. General introduction the the of When I was appointed at Rijksherbarium, Leyden, to study Gramineae Malesia, I was in one way fortunate to find an almost finished manuscript by the late Dr. P. Jansen, who treated about650 species occurring in the area. Some ofmy colleagues it for its size had started to prepare pubhcation, but were forced to give this up because other made and their activities did not agree. Mention must be of Dr. J. Kern, Mr. Ch. Monod de and to all of whom Froideville, Dr. C. G. G. J. van Steenis, I express my thanks for their tuition, discussions, help, and friendship. When started with studies to tackle of I my it was suggested to me a fairly large genus which a recent revision was available in order to get acquainted with Jansen's work and in the with grasses in general. Digitaria, reportedly with 32 species region, seemed a good object, especially since it had been revised by my predecessor at the Rijksherbarium, of would Dr. J. Th. Henrard, whereby a good number important specimens be available became immediately. It soon apparent, however, that merely checking descriptions, filling in recent literature, and other editorial work would not be sufficient and a thorough the results ofwhich this treatment was undertaken, are presented in paper. Henrard's of the will stand for time 'Monograph genus Digitaria' (1950)*) a long as the foundation of any work on the genus. It is therefore in the following referred to by and a short discussion show and weaknesses. page only seems in place to its importance its Such in there be large monographs are becoming a rarity taxonomy, as seems to a tendency to spend an amount of time on a genus in reverse relation to its size, whereby the thereforethe the and larger ones, and ones giving greatest problems, remain neglected in confusion. his studies of Aristida Henrard's chief As in previous (1926—1933; 1929—1933) purpose was to typify all names ever published in Digitaria, to examine, evaluate, and figure the in On type specimens order to be able to name all specimens readily at hand. this basis a of the could be and subdivision genus composed and a key to the species infra-specific taxa prepared. for each In the published work all names, accepted or not, are arranged alphabetically, the when and homo- basionym, present, some or heterotypic synonyms (but not all!) are given, and the text of the original description(s) is/are copied. When possible a spikelet of the type-specimen is depicted (magn. X 20), and notes, critical remarks, additional of the descriptions, and comparisons with relatedtaxa are given. Thus the mainbulk work of the consists bibliography and typology. As the type-setting of manuscript was started during the last World War, an appendix became necessary for the names which were him published during that period, but became available to only after the Liberation. the end to the the the and the At keys are given 4 subgenera, 32 sections, ca. 325 species, infra-specific taxa; in these keys the actual descriptions of the taxa are built in. of the The absence a general index makes it hard to unearth information laid down in this book, especially since the author occasionally changed his mind about nomenclature, *) Henrard (1950); when only a page number is cited, reference is always made to this pubhcation. J. F. VELDKAMP: A revision of Digitaria in Malesia 3 taxonomic without status, or position, noting this under the taxon concerned. Very often, and under important descriptions comparisons are given little related taxa, which infor- mation is then only stumbled on accidentally. The foundation of the book laid in the that the method was period type in plant advocated taxonomy was strongly by some American agrostologists, mainly A. S. Hitchcock and Miss Agnes Chase; this apparently greatly influenced Henrard's method From this it be is and thought. can explained why so much stress being placed on type the specimens, whereby other, nomenclaturaly less important collections are relatively extensive the when neglected. Hardly ever are descriptions given, showing variability, and be with others. the odd they are present, they cannot compared Even in keys, mixtures of and important characters irrelevant remarks are given. It is regrettable that the keys are the be not too well compared with descriptions, whereby species may keyed out on characters which in the keys to their section are explicitly declared to be absent. E.g. maniculata with binate D. Stapf and D. patagiata Henr. spikelets are placed in sect. Verrucipilae ('spikelets always ternate', p. 852), D. didactyla Willd., D. meziiKanehira, and others with cataphylls are considered to belong to sect. Sanguinales, although the key (p. 860) defines these as 'Culms not thickened at the base, without cataphylls', etc. the much often attributed In delimitation of sections too importance is to a certain number of characters which unfortunately prove to be not so stable and unequivocal as will be in relevant thought by Henrard, as shown the chapter (p. 12). the of As far as delimitation species and infra-specific taxa is concerned, Henrard and I are frequently at odds. He has a tendency, which he admits (p. 841), to recognize 'small' of the often be the other taxa, which, in view scarce material, may a wise thing. On hand such taxa may be expected to be the extremes of a range of sympatric variability or the result of geographical distributional patterns. and of Henrardbased his conclusions interpretations on the application Vavilov's Law of homologous series in variation (1922), by which it is suggested that variations of the same nature should be given equal rank. Henrard thus called all taxa with bristled sterile lemmas ('pectinate') parallel subspecies, disregarding the genetical background of which he was also under and occasionally aware (see Infra-specific taxonomy genetics, p. 17). of where be It is, course, always difficult to decide taxonomic lines should drawn for specific and infra-specific distinction, but I have tried to apply this rule: when forms are connected and which by numerous intergrading specimens so no character on they can be to divided is correlated by another, these forms are considered belong to a single of ofthe of be taxon, although specimens the extremes range variability can easily recog- nized. In following this rule I have in several cases united a considerable number of taxa kept separate by Henrard and other botanists. Not all will therefore agree with the course I have taken. Such differences are to be expected in complicated situations as these, which when he tried what he made even Hooker / (1896) write in exasperation, to sort out called Paspalum sanguinale Lamk.: '...as to the result, I am satisfied that no two botanists over the materials wouldarrive the same working independently same at (results), or agree in any other...' and indeed, his and Henrard's and my interpretation differ considerably.