THE NEW PHYTOIiOGIST. VOL. 4. No. 7. JULY 31 ST, 1905. PROVISIONAL SCHEME OF THE NATURAL (PHYLOGENETIC) SYSTEM OF FLOWERING PLANTS. BY HANS HALLIER, PH.D. (Hamburg). S the son of a well known botanist and the grand-nephew of M. J. Schleiden, the centenary of whose birth was celebrated lasAt year at Hamburg and Jena, I have by inheritance and edu- cation a passion for botany, and for nearly thirty years 1 have taken a zealous interest in taxonomy. Even at the age of seven to thirteen years I used to accompany my father, the late Ernst Hallier, formerly professor of botany at the University of Jena, on the botanical excursions which he undertook every Saturday or Sunday with his students, in order to introduce them to the principles of systematic botany. In these instructive excursions I soon gained a knowledge of the botanical names of plants and of our native flora, and learned the natural system by immediate intuition and comparison of the objects themselves, independent of the sometimes very dogmatic views of the standard-books, or, as we say in Germany, " mit einem noch nicht durch Fachkenntnis getriibten Blick." Later, at the University of Jena, I was intro- duced by the works of Darwin and the lectures and practical instructions of Ernst Haeckel, to the marvellous series of dis- coveries, to which the evolution-theory had been the impulse. In the Botanical Laboratory of Professor L. Radlkofer and Dr. H. Solereder at Munich, I recognized that not only the external characters of plants must be examined in determining their affini- ties, but that comparative anatomy is also indispensable to systematic botany.' During a four years' stay at the famous botanic garden of Buitenzorg and during an expedition into the ' See H. Solereder's Systematische Anatomie der Dicntyledonen. Stuttgart, 1899. 152 Hans Hallier. centre of Borneo' I had an excellent opportunity of examining representatives of nearly all the natural orders of Flowering Plants under natural conditions. The academical lectures of Professor Ernst Stahl, as well as the personal influence of this suggestive botanist and of Professor Jean Massart, my enthusiastic companion in many excursions in tbe vicinity of Buitenzorg-, induced me to apply to systematic botany, the results of plant-ecology and mor- phogeny. As a result of these various influences I reached the conviction that there can exist only one really natural system, namely that which is identical with the tree of descent; to recon- struct this, systematic botany should be founded on a much broader and more universal base than at present, comprehending not only the morphology of the reproductive organs, but also all the other branches of botany, such as comparative morphology of the vegetative organs ; comparative anatomy, ontogeny and embry- ology ; phytochemistry, physiology and ecology ; structure of pollen and seed coat; relations to climate, seasons and to the sui'rounding organic world ; plant geogi'aphy ; palaeo-phytology, etc. Thus since the elaboration of my first botanical publication (in 1890-2) till now I have always paid special attention to these points in reference to natural affinity. The results of these, comparative studies have been published in a series of papers, most of which refer not to the whole system of flowering plants, but to single orders or alliances. It was only on my second voyage to tlie tropics, that I felt impelled to publish, in April 1903, a provisional account of my system as a whole. At that time I had to take into account the possibility that the Tagal people might not let me out of the Phillipine Islands, or that a typhoon might throw me into a shark's mouth or into the depths of the South Sea, and I therefore thought it wise to publish my system at once, incomplete as it was. Moreover I hoped, that during my absence competent botanists would have time and leisure to digest my new system and to subject it to discussion, but in this latter point I am somewhat disappointed. Hitherto reviews on my system have been few in number and several of them very diffident or even unfavourable. The more favourable ones are the following. • The results of the botanical explorations of this expedition have been described in the Natiiiirkiiftdig; Tijihchrift voor Nedcr- Inndsch Indie LIV. (1895) pp. 406-449 and in the Naiurwisscn- scliaftUchc IVoclwn sell rift, XI. (Berlin 1896). ' See his interesting descriptions of these trips in his paper, Uu botaiiiste cn Malaisic, published in the litilletin dc Id Societe royale dc botaniquc dc llclgiquc, XXXIV. (1895), part 1. Phylogenetic System of Flowering Plants. 153 In the preface to his German edition of Warming's Manual of Systematic Botany (1902), Moebius refers briefly to my opinion that the Synipcialac arc of potyphyletic orij|in. On pp. 411 and 137 of the sixth, and on pp. 418 and 443 of the seventh edition of Strasburger, Noll, Schenck and Karsten's Text-Book of Botany (Jena, 1904 and 1905), Karsten recapitulates my opinions of the origin of Dicotyledons, Monocotyledons, Choripetnlae, Syinpetalne and Anicntiflorae. In his paper entitled. Die Grundlagen des Hallierschen Angiospermensystems, eine phylogenetische Studie {Bcihcftc z. Dotan. CcntrulUatt, XVII. (1904), pp. 129-156), Gustav Senn, lecturer on Systematic Botany at the University of Basel, undertakes a very careful and critical examination of the principles on which my new system is founded, and in Just's Annual Report on tlie botanical literature of 1903, Fedde reports at great length on my different publications of that year. Only partly favourable are Wettstein's reviews of my paper on morphogeny and phylogeny (Hamburg, 1903) in the Oesterrekliische Dotan. Zcitschrift LIII. (1903) and in the Botanisclie Zeitiing, LXI. (1903), section II. pp. 311-314. Unfortunately, with few exceptions, this eminent hotanist does not indicate precisely nor in detail which of my opinions he considers as inacceptable, and in his remarks on Gnetacesc, I am convinced that his criticism is not well founded. In external characters, as in anatomical structure, the Gnetacea: approach very closely to certain Lorantbaceae, and to Myzodcndriim, and there is much evidence that they belonjj to this cycle of aflinity, if only we presume that the so-called nucellus of Gnetuvi repre- sents not a single ovule, but a placenta with several ovules, as Treub has indicated in some Loranthaceae. The most striking point in the reception of my system is the silence of Professor Engler. I am much disappointed that a scientiBc journal which is a recognized centre for systematic botany and plant-geography has been unable to discuss in extenso a new system, which is exceptional by the complexity of principles applied in it. But in the volumes of the Jahrbucher since 1902, there is no mention of my publications, and the same is the case in the monographs of the " Pflansenreich." In KOhne's Monograph of Lythracese (Oct. 1903) and in Winkler's Monograph of Betalaceae (June 1904) my publications treating the same topics are neglected. Only Buchenau in an appendix to his monograph of Alismataceae refers to Miss E. Sargant's and my own suggestions on the mutual relations of Monocotyledons and Dicotyledons. 154 Hans Hallier. The general features of my system are the following: The Angiospcrmae are a natural (monophylctic) group, ;ind not a polyphylctic one, as suggested by Engler in Engler and Prantl's Ndtiirlichcn Pflnnzciifamilieu, Nachtrag zu 11.—IV. (1897), pp. 364—369. The Anienlaccae are not to be considered as old types, remaining in a lower state of development, and iillies or descendants of Gymiiospermae, but, on the contrary, as the highest and most reduced types of one of the lines of Dicotyledons. They and all the other lines of Dicotyledons have been developed by reduction in flower and fruit from the Polycarpicae, the latter group being derived immediately (rom Bcnncttitnceae or other extinct Cycadales. In the same manner the Liliijlorae and all the other syncarpous Monocotyledons have been derived by union of the carpels, by reduction in the numher of parts, by epigynous insertion of the perianth, and by other changes in the structure of flower and fruit from the polycarpous Monocotyledons (//f/o^)?r7f), which latter group originated immediately from the polj-carpous Dicotyledons (Poly- carpicae and Raiiales). In the Dicotyledons the Apetalae and Syinf^etnlae arc unnatural groups of polyphyletic origin. Agreeing in some points with mine, and likewise phylogenetic, is the system which Professor C. E. Bessey, of the Nebraska University, published eight years ago in the Botanical Gazette, Vol. XXIV. I do not claim for my system the position of an infallible gospel or of a " Nolimetangere," the latter very significant expression being used by Professor Karsten on p. 443 of the seventh edition of the Bonn Text-Book of Botany (1905). On the contrary, I freely confess that my system gives only an approximate idea of the lines of descent and of the mutual relations of the Flowering Plants; it is only one step in the further progress of phylogenetic botany. But I am sure that this step is not a wrong and useless one, and that it will lead to a broader knowledge of the natural affinities of Flowering Plants. The following is a chronological enumeration of the publications in which I have worked out my system. 1. Versuch einer naturlichen Gliederung der Convolvulaceen auf anatomischer und morphologischer Grundlage. Engler's Botanische yahrhucher, XVI., 4—5 (1893), p. 486. 2. Betrachtungen iiber die Verwandtschaftsbeziehungen der Ampelideen und anderer Pflanzenfamilien. Natuurhmdig Tijdschrift voor Ncderlandsch Indie, LVI., 3 (1893), p. 486. Phylogenetic System of Flowering Plants. 155 3. Die indonesischen Clematideen des Herbariums zu Bui- Aniiales dn jardiii boUuiiquc de Bicitenzorg, XIV, 2 (July, 1897), p.