Outline of the classification of flowering plants (Magnoliophyta)

The design and function of leaf venation are important to plant performance, with key implications for the distribution and productivity of ecosystems, and applications in paleobiology, agriculture and technology. We synthesize classical concepts and the recent literature on a wide range of aspects of leaf venation. We describe 10 major structural features that contribute to multiple key functions, and scale up to leaf and plant performance. We describe the development and plasticity of leaf venation and its adaptation across environments globally, and a new global data compilation indicating trends relating vein length per unit area to climate, growth form and habitat worldwide. We synthesize the evolution of vein traits in the major plant lineages throughout paleohistory, highlighting the multiple origins of individual traits. We summarize the strikingly diverse current applications of leaf vein research in multiple fields of science and industry. A unified core understanding will enable an increasing range of plant biologists to incorporate leaf venation into their research.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.12253

Leaf venation: structure, function, development, evolution, ecology and applications in the past, present and future

We have amassed structural data for 108 characters and 52 taxa of magnoliids and basal monocots and eudicots, including observations by P. K. Endress and A. Igersheim on flowers. These data were analyzed separately and in combination with rbcL, 18S, and atpB sequences. Besides confirming agreements between previous analyses of both kinds of data (reduction of Magnoliales to six families; relation of Piperaceae, Saururaceae, Lactoris, and Aristolochiaceae), trees based on this data set show shifts toward molecular results (separation of Illiciaceae and Schisandraceae from Winteraceae and of Amborella, Austrobaileya, Trimeniaceae, and Chloranthaceae from Laurales; relation of Winteraceae and Canellaceae) plus continued conflicts (association of Chloranthaceae with Amborella and Trimeniaceae and of Nymphaeales with monocots). In cases where molecular and morphological trees conflict, combined analyses of morphological and molecular data generally yield the same topologies as molecular analyses, but morpholog...

https://www.jstor.org/stable/10.1086/317578

Morphological Phylogenetic Analysis of Basal Angiosperms: Comparison and Combination with Molecular Data

Our attempt at putatively phylogenetic classifications of Angiospermae, considering our vast ignorance of more than 120 million years of evolution of the class, must be very tentative and elastic to make full use of the new approaches and new data constantly being made available to us. Some of the realignments thus required in my system of classification are here explained. Among others, the Paeoniales are recognized and include Glaucidiaceae; various shifts of families are made within Thei–florae–Violiflorae–Malviflorae; Thymelaeaceae and Simmondsiaceae are transferred to Euphorbiales; Emblingiaceae, Gyrostemonaceae and Bataceae are added to Sapindineae; Fabineae, with Connaraceae, Surianaceae and Fabaceae, are transferred to Rutiflorae; Proteiflorae are placed near Rutiflorae, especially Fabineae; the largely Australasian–African Pittosporales are explained; Cornaceae are severely pruned; Haemodoraceae and Velloziaceae are transferred to Commelinales; Arecales, Cyclanthales and Pandanales are separated into unrelated superorders; and Typhiflorae are moved into closer proximity with Commeliniflorae.

Proposed new realignments in the angiosperms

IT is an interesting coincidence that two books dealing systematically with the Dicotyledons should appear about the same time. The much-delayed second volume of Dr. Rendle's “The Classification of Flowering Plants” was issued at the close of 1925, and Mr. Hutchinson's work, herein reviewed, at the opening of the present year. The manner of their appearance suggests a prediction to the effect that one marks the close of a chapter and the other the opening of a new one in British systematic botany. The classification of Engler upon which Rendle's useful and informative text-book is based has, we venture to say, run its course, and botanists generally, at any rate the younger school, will welcome this refreshing and originally conceived handbook of Mr. Hutchinson's, with its new classification professedly framed on phylogenetic lines and actually at any rate on sound and stimulating ones. The Families of Flowering Plants. 1. Dicotyledons. Arranged according to a new System based on their Probable Phylogeny. By J. Hutchinson. Pp. xiv + 328. (London: Macmillan and Co., Ltd., 1926.) 20s. net.

The Families of Flowering Plants

The phylogeny of the stamen

The telome theory and the origin of the stamen

Studies on the morphology and anatomy of the flower, primarily upon the vascular system, have in the past several decades increased in both number and importance. The postulate that the vascular tissues of the flower are conservative, and therefore reveal evolutionary changes to a greater degree than do external forms, has been the basis of most of these studies. The result of much of this work has been (1) to contribute to a clarification of many morphological puzzles in connection with the flower, and (2) to furnish additional evidence leading to the perfection of a natural or phylogenetic system of classification (Eames, 20). With respect to the contribution of anatomy to the establishment of phylogenetic lines, affinities between groups have in many cases been revealed more clearly than has been possible by studies on external morphology; these studies have in some cases supported current concepts of relationships; in other cases they have been at variance with them. In certain instances, on the other hand, anatomical work has so far revealed only that groups hitherto considered primitive are highly reduced, that is, that reduction has proceeded to the extent that relationships cannot be shown. In addition to these aspects of work on the flower, a number of new points of view have arisen with respect to the nature and origin of floral structures ; certain of these have already been reviewed (7).

The morphology of the flower

Morphologists have long been concerned with the fundamental nature of the vascular plant body-with the relationships between root, stem and leaf, and with the origin of reproductive structures. Attempts at analysis on the basis of either formal or phyletic morphology have given rise to a number of theories dealing with the organization of the plant body. Those related to the flowering plants are summarized by Arber (1930) and need not concern us here, since they are of historical interest only. A theory which encompasses a consideration of all vascular plants, and which is based primarily upon studies of the lower Tracheophyta, recent and fossil, has had greater vitality-so much so, indeed, that it has permeated the thinking of many morphologists and paleobotanists to a degree not realized by those who have not followed the literature in these fields. This is the telome theory, perhaps better termed the " telome concept". Among other aspects the telome concept has assisted in a clarification of our ideas on the relationships between root, stem and leaf, and emphasizes that the plant body is an axis, with a descending portion, the root, and an aerial portion, the shoot, whose appendages are merely modified parts of the stem. Before considering the telome theory itself, it is desirable to point out that, like many another concept, it did not arise de novo, but was foreshadowed by the work of earlier investigators. Reference will repeatedly be made to a fundamental principle advocated by all of these workers which is an essential part of the telome theory itself. This is the principle of overtopping, shown diagrammatically in its simplest form in Fig. 1. This principle involves the belief that the oldest method of branching was dichotomous (a dichopodium). If, at each fork, one of the two branches becomes stronger than the other, a sympodium will result, with an apparent main axis composed of one of the two forks. Continued development of the main axis results in a monopodium which gives off

The telome theory

Application of 2,4-D to soil as a pre-emergence spray to prevent lodging and to control weeds in -sweet corn. Michigan Agric. Exp. Sta. Quart. Bull. 30: 194-200. , AND H. B. TUKEY. 1944. Selective herbicidal action of midsummer and fall applications of 2A-dichlorophenoxyacetic acid. Bot. Gaz. 106: 232-245. KAISER, S., AND H. C. ALBAUX. 1939. Early root and shoot growth in two varieties of Avena sativa in relation to growth substances. Amer. Jour. Bot. 26: 749-754. LEVINE, M., AND J. LEIN. 1944. The effects of various growth substances on the number and length of roots of Allium cepa. Amer. Jour. Bot. 28: 163-168. MARTH, P. C., AND J. W. MITCHELL. 1944. 2,4-D as a differential herbicide. Bot. Gaz. 106: 223-232. 1946. Effect of spray mixtures containing 2,4-D, urea, fermate on the growth of grass. Bot. Gaz. 107: 417-424. MITCHELL, J. W., AND P. C. MARTH. 1945. Effects of 2,4-D on the growth of grass plants. Bot. Gaz. 107: 276-284. ROSSMAN, C., AND D. W. STANIFORTH. 1949. Effects on inbred lines and a single cross of Maize. Plant Physiol. 24: 60-74. WATSON, D. P. 1948. An anatomical study of the modification of the bean leaves as a result of treatment with 2,4-D. Amer. Jour. Bot. 35: 543-555.

Carl L. Wilson

Papers

The phylogeny of the stamen

The telome theory and the origin of the stamen

The morphology of the flower

The telome theory

Vasculation of the stamen in the melastomaceae, with some phyletic implications