Full text of "The genus Bidens .."

THE UNIVERSITY

OF ILLINOIS

LIBRARY

jUN L-;

HOV13 '358

BOTANICAL SERIES

FIELD MUSEUM OF NATURAL HISTORY

FOUNDED BY MARSHALL FIELD, 1893

VOLUME XVI

THE GENUS BIDENS

PART I

EARL EDWARD SHERFF

RESEARCH ASSOCIATE IN SYSTEMATIC BOTANY

B. E. DAHLGREN

CURATOR, DEPARTMENT OF BOTANY
EDITOR

THE LIBRARY OF THE

OCT8-1937

UNIVERSITY OF ILLINOIS

PUBLICATION 388

CHICAGO, U.S.A.
AUGUST 31, 1937

BOTANICAL SERIES

FIELD MUSEUM OF NATURAL HISTORY

FOUNDED BY MARSHALL FIELD, 1893

VOLUME XVI

THE GENUS BIDENS

PART I

THE LIBRARY OF THE

OCT8-1937

UNIVERSITY OF ILLINOIS

EARL EDWARD SHERFF

RESEARCH ASSOCIATE IN SYSTEMATIC BOTANY

B. E. DAHLGBEN

CURATOR, DEPARTMENT OP BOTANY
EMTOR

PUBLICATION 388

CHICAGO, U.S.A.
AUGUST 31, 1937

PRINTED IN THE UNITED STATES OF AMERICA
BY FIELD MUSEUM PRESS

580.5
FB

CONTENTS

LIST OF ILLUSTRATIONS 5

PREFACE 11

HISTORICAL SURVEY OF GENUS BIDENS 17

MORPHOLOGY, HISTOLOGY, CYTOLOGY, ECOLOGY, AND OTHER SPECIAL LINES
OF INQUIRY 25

DESCRIPTION OF GENUS BIDENS 29

SYNOPSIS OF SECTIONS 30

KEY (C LA vis)

Plants Native to Islands of Central Pacific Ocean 33

Plants Growing in North and Central America and in the West Indies ... 45

Plants of South America 55

Plants of the Eastern Hemisphere, excluding Africa 59

Plants of Africa 60

ABBREVIATIONS USED FOR HERBARIA CITED 71

DESCRIPTIONS 73

NAMES TO BE EXCLUDED FROM BIDENS 633

ADDENDA 645

NAMES OF UNCERTAIN STATUS (INCERTAE SEDIS) 646

INDEX OF COLLECTORS CITED 649

GENERAL INDEX . 693

1 056907

LIST OF ILLUSTRATIONS

PLATES

FACING
PAGE

I. Bidens polycephala Schz. Bip. (figs, a-h) 80

Bidens Ahnnei Sherff (figs, i-p) , 80

II. Bideiis Jardinii Schz. Bip 82

III. Bidens Lantanoides Gray (figs, a-g) 84

Bidens cordifolia Schz. Bip. (figs, h-n) 84

IV. Bidens australis Spreng 86

V. Bidens Mathewsii Sherff 90

VI. Bidens Henryi Sherff (figs, a-i) 92

Bidens pulchella (Less.) Schz. Bip. (figs, j-p) 92

VII. Bidens glabrata (Gray) Sherff. ..'.... 94

VIII. Bidens liawaiensis Gray 96

IX. Bidens distans Sherff 98

X. Bidens micrantha Gaud. (figs, a-h) 100

Bidens Degeneri Sherff (figs, i-o) 100

XI. Bidens asymmetrica (Levl.) Sherff 102

XII. Bidens asymmetrica (Levl.) Sherff (figs, a-i) 106

Bidens cuneata Sherff (figs, j-p) 106

XIII. Bidens torta Sherff (figs, a-g) 108

Bidens cervicata Sherff (figs, h-p) 108

XIV. Bidens graciloides Sherff (figs, a-g) 110

Bidens waianensis Sherff (figs, h-p) 110

XV. Bidens ctenophylla Sherff 112

XVI. Bidens ctenophylla Sherff 114

XVII. Bidens macrocarpa (Gray) Sherff (figs, a-i) 116

Bidens magnidisca Deg. & Sherff ex Sherff (figs, j-l) 116

XVIII. Bidens micranthoides Sherff 118

XIX. Bidens Asplenioides Sherff (figs, a-/) 122

Bidens Stokesii Sherff (figs, g-o) 122

XX. Bidens Populifolia Sherff 124

XXI. Bidens Skottsbergii Sherff 126

XXII. Bidens obtusiloba Sherff 128

XXIII. Bidens sandvicensis Less. (figs, a-h) 130

Bidens waimeana Sherff (figs, i-o) 130

XXIV. Bidens conjuncta Sherff (figs, a-h) 132

Bidens fulvescens Sherff (figs, i-o) 132

XXV. Bidens Wiebkei Sherff 134

XXVI. Bidens coartata Sherff 138

XXVII. Bidens Salicoides Sherff 140

XXVIII. Bidens Forbesii Sherff 142

XXIX. Bidens fulvescens Sherff 144

XXX. Bidens Campylotheca Schz. Bip 146

XXXI. Bidens valida Sherff 148

XXXII. Bidens amplectens Sherff 150

XXXIII. Bidens sandvicensis var. setosa Sherff (figs, a-l) 154

Bidens Bipontina Sherff (figs, m, n) 154

Bidens Menziesii (Gray) Sherff (figs, o, q-v) and var. filiformis

Sherff (fig. p) 154

LIST OF ILLUSTRATIONS

XXXIV. Bidens Hillebrandiana (Dr. del Cast.) Deg. ex Sherff 156

XXXV. Bidens mauiensis (Gray) Sherff (figs, a, e); var. cuneatoides

Sherff (figs, b-d, f-o) 158

XXXVI. Bidens molokaiensis (Hillebr.) Sherff 160

XXXVII. Bidens Cosmoides (Gray) Sherff 162

XXXVIII. Bidens darendonensis Britt 164

XXXIX. Bidens monticola Poepp. & Endlich 166

XL. Bidens reptans (L.) G. Don 170

XLI. Bidens reptans var. Urbanii (Greenm.) 0. E. Schulz 172

XLII. Bidens reptans var. Urbanii (Greenm.) 0. E. Schulz (figs, a-h) ;

var. dissecta O. E. Schulz (figs, i-s) 174

XLIII. Bidens incisa (Ker) G. Don 176

XLIV. Bidens squarrosa H.B.K 178

XLV. Bidens squarrosa H.B.K. (figs, a-g) 180

Bidens Vincaefolia Karst. & Schz. Bip. ex Sherff (figs, h-m) 180

XLVI. Bidens Rubifolia H.B.K 182

XLVII. Bidens simplicifolia C. H. Wright 186

XLVIII. Bidens urophylla Sherff 188

XLIX. Bidens segetum Mart, ex Colla 190

L. Bidens segetum Mart, ex Colla 192

LI. Bidens segetum var. patula (Gardn.) Sherff 194

LII. Bidens Shrevei Britt 196

LIII. Bidens Holwayi Blake & Sherff 204

LIV. Bidens graveolens Mart 206

LV. Bidens fistulosa Schz. Bip. ex Baker 212

LVI. Bidens Bidentoides (Nutt.) Britt 220

LVII. Bidens Eatonii Fern. (figs, a-/); var. fallax Fern. (fig. g) 224

LVIII. Bidens aristosa (Michx.) Britt. (fig. h); var. mutica Gray ex

Gatting. (figs, a-g); var. Fritcheyi Fern. (fig. i) 228

Bidens polylepis Blake (figs, k-r); var. retrorsa Sherff (fig. s) 228

LIX. Bidens mitis (Michx.) Sherff (figs, a-l) 236

Bidens coronata (L.) Britt. (figs, m, p-u);var. tenuiloba (Gray)

Sherff (figs, n, o) 236

LX. Bidens Oerstediana Sherff 240

LXI. Bidens discoidea (Torr. & Gr.) Britt 242

LXII. Bidens frondosa L. (figs, a, c-h); var. anomala Port, ex Fern.

(fig. i); var. stenodonta Fern. & St. J. (fig. 6) 244

LXIII. Bidens vulgata Greene (figs, a, c-h); var. schizantha Lunell

(fig. b) 252

LXIV. Bidens comosa (Gray) Wieg 254

LXV. Bidens connata Muhl. ex Willd. (fig. d); var. anomala Farwell
(fig. k); var. petiolata (Nutt.) Farw. (figs, a, f-j); var.
pinnata Wats. (fig. e); var. fallax (Warnst.) Sherff (figs.

b, c) 258

LXVI. Bidens heterodoxa Fern. & St. J. (figs, a, c-g); var. orthodoxa

Fern. (figs. 6, h) 260

LXVII. Bidens tripartita L. (figs, a, b, d-i); var. cernuaefolia Sherff

(fig. c) 262

LXVIII. Bidens tripartita var. repens (D. Don) Sherff (figs, a-/) 266

Bidens lineariloba Oliv. (figs, g-o) 266

LIST OF ILLUSTRATIONS

LXIX. Bidens radiata Thuill. (figs, a-g) 268

Bidens tripartite var. orientalis (Velen.) Sherff (figs, h-ri) . . 268

LXX. Bidens tripartita var. hirta (Jord.) Sherff 270

LXXI. Bidens amplissima Greene 272

LXXII. Bidens cernua L. (figs, a, d-k); var. oligodonta Fern. & St. J.

(figs. 6, c) 276

LXXIII. Bidens laevis (L.) B.S.P 284

LXXIV. Bidens hyperborea Greene (figs, b, d, f, h, j, 1) ; var. gaspensis

Fern. (figs, a, c, e, g, i, k, m) 288

LXXV. Bidens diversa Sherff (figs, a, 6, d-i); var. megaglossa Sherff

(fig. c) 290

LXXVI. Bidens Schaffneri (Gray) Sherff 292

LXXVII. Bidens Ferulaefolia (Jacq.) DC 300

LXXVIII. Bidens Ferulaefolia var. Foeniculaefolia (DC.) Sherff (figs.

a-i); var. ludens (Gray) Sherff (figs. /-) 302

LXXIX. Bidens Townsendii Sherff 304

LXXX. Bidens aurea (Ait.) Sherff 306

LXXXI. Bidens integrifolia Brandeg 308

LXXXII. Bidens amphicarpa Sherff (figs, a-i) 316

Bidens oligocarpa Sherff (figs, j-l) 316

LXXXIII. Bidens oligantJia Brandeg. (figs, a-h) 318

Bidens Anthriscoides DC. (figs, i-q) 318

LXXXIV. Bidens Anthemoides (DC.) Sherff (figs, a-j) 320

Bidens Andrei Sherff (figs, fc-s) 320

LXXXV. Bidens Chrysanthemifolia (H.B.K.) Sherff 322

LXXXVI. Bidens mollifolia Sherff 324

LXXXVII. Bidens Abadiae DC. (figs, a, c-i); var. pilosoides Sherff (fig. 6) 332

LXXXVIII. Bidens Brandegeei Sherff (figs, a-k) 334

Bidens canescens Bertol. (figs, l-s) 334

LXXXIX. Bidens Bigelovii Gray (figs, a-k) 348

Bidens bipinnata L. (figs, l-s) 348

XC. Bidens leptocephala Sherff 350

XCI. Bidens Engleri O. E. Schulz (figs, a-f) 354

Bidens cylindrica Sherff (figs. 0-0 354

XCII. Bidens pseudalausensis Sherff (figs, a-g) 356

Bidens cornuta Sherff (figs, h-n) 356

XCIII. Bidens tenuisecta Gray 362

XCIV. Bidens paupercula Sherff 364

XCV. Bidens Pringlei Greenm. (figs, a-h) 366

Bidens heterosperma Gray (figs, i-o) 366

XCVI. Bidens exigua Sherff (figs, a-i) 370

Bidens duranginensis Sherff (figs, j-q) 370

XCVII. Bidens parviflora Willd. (figs, a-g) , 372

Bidens Lemmonii Gray (figs, h-n) 372

XCVIII. Bidens capillifolia Sherff 374

XCIX. Bidens biternata (Lour.) Merrill & Sherff (figs, a, c-m) 376

Bidens pilosa L. (fig. 6) 376

C. Bidens biternata var. glabrata f. abyssinica (Schz. Bip.) Sherff 378

CI. Bidens andicola var. Cosmanlha f. Buchtienii Sherff (figs, a-g) 380

Bidens pseudocosmos Sherff (figs, h-n) 380

LIST OF ILLUSTRATIONS

CII. Bidens pilosa L. (figs, a, b, e-j) ; var. minor (Bl.) Sherff (figs, c,

d, k-r) 382

CIII. Bidens pilosa var. radiata Schz. Bip. (figs, a-h) 386

Bidens tenera O. E. Schulz (figs, i-o) 386

CIV. Bidens pilosa var. bimucronata (Turcz.) O. E. Schulz (figs, a-i) 388

Bidens acuticaulis Sherff (figs, j-r) 388

CV. Bidens pilosa var. bimucronata f. odorata (Cav.) Sherff 390

CVI. Bidens pilosa var. bimucronata f. odorata (Cav.) Sherff (figs.

a-h); var. alausensis (H.B.K.) Sherff (figs, i-o) 392

CVII. Bidens pilosa var. alausensis f. Scandicina (H.B.K.) Sherff 394

CVIII. Bidens pilosa var. calcicola (Greenm.) Sherff 396

CIX. Bidens pilosa var. calcicola (Greenm.) Sherff (figs, a, c-j);

f . dissecta Sherff (fig. b) 398

Bidens aequisquama (Fern.) Sherff (figs, k-t) 398

CX. Bidens subalternans DC 402

CXI. Bidens domingensis 0. E. Schulz 404

CXII. Bidens Malmei Sherff 406

CXIII. Bidens Cynapiifolia H.B.K 408

CXIV. Bidens riparia H.B.K. (figs, i-p); var. refracta (Brandeg.)

O. E. Schulz (figs, a-h) 410

CXV. Bidens Sambucifolia Cav 412

CXVI. Bidens Gardneri Baker 414

CXVII. Bidens flagellaris Baker 418

CXVIII. Bidens nudata Brandeg 420

CXIX. Bidens brasiliensis Sherff .422

CXX. Bidens Riedelii Baker (figs, a-k) ; var. Hassleriana Chod. (fig. I) 424

CXXI. Bidens Chodati Hassl 426

CXXII. Bidens angustissima H.B.K. (figs, h-m); var. Linifolia (Schz.

Bip. ex Klatt) Sherff (figs, a-g) 428

CXXIII. Bidens andicola H.B.K. (figs, a-d, h-p)', var. Cosmantha
(Griseb.) Sherff (fig. e); var. decomposita O. Ktze. (figs.

/, g) 430

CXXIV. Bidens andicola var. Cosmantha (Griseb.) Sherff 434

CXX V. Bidens microphylla Sherff 436

CXXVI. Bidens triplinervia H.B.K. (figs, j, k); var. macrantha (Wedd.)

Sherff (figs, a-i, l-v) 438

CXXVII. Bidens triplinervia var. hirtella (H.B.K.) Sherff 440

CXXVIII. Bidens triplinervia var. macrantha (Wedd.) Sherff (figs, j-p);

var. mollis (Poepp. & Endlich.) Sherff (figs, a-i) 442

CXXIX. Bidens serrulata (Poir.) Desf 444

CXXX. Bidens chiapensis Brandeg. (figs, a-i) 446

Bidens Geraniifolia Brandeg. (figs, j-o) 446

CXXXI. Bidens Ostruthioides (DC.) Schz. Bip 450

CXXXH. Bidens Ostruthioides var. costaricensis (Benth. ex Oerst.) Sherff 452

CXXXIII. Bidens bicolor Greenm 454

CXXXIV. Bidens Holstii (O. Hoffm.) Sherff 456

CXXXV. Bidens Holstii var. rupestris Sherff 458

CXXXVI. Bidens kamerunensis Sherff 460

CXXXVII. Bidens Grantii var. Stapfii Sherff (figs, a-i) 462

Bidens Steppia (Steetz) Sherff (figs, j-r) .462

LIST OF ILLUSTRATIONS

CXXXVIII.

cxxxix.

CXL.

CXLI.
CXLII.

CXLIII.

CXLIV.

CXLV.

CXLVI.

CXLVII.

CXLVIII.

CXLIX.

CL.

CLI.

CLII.
CLIII.
CLIV.

CLV.
CLVI.

CLVII.

CLVIII.

CLIX.

CLX.

CLXI.

CLXII.

CLXIII.

CLXIV.

CLXV.

CLXVI.

CLXVII.

CLXVIII.

CLXIX.

CLXX.

Bidens rufovenosa Sherff (figs, a-i) 466

Bidens leptolepis Sherff (figs, j-p) 466

Bidens asperata (Hutch. & Dalz.) Sherff 468

Bidens urceolata DeWild. (figs, a-g) 470

Bidens rubra DeWild. (figs, h-o) 470

Bidens taitensis Sherff 472

Bidens Fischeri (O. Hoffm.) Sherff (figs, a-h) 474

Bidens Schimperi Schz. Bip. ex Walp. (figs, i-q) 474

Bidens Schimperi Schz. Bip. ex Walp 476

Bidens Schimperi Schz. Bip. ex Walp. (forms) 478

Bidens Kirkii (Oliv. & Hiern) Sherff 482

Bidens musoziana Sherff 484

Bidens Mossii Sherff 486

Bidens Whytei Sherff (figs, a-g) 488

Bidens ambigua S. L. Moore (figs, h-m) 488

Bidens microcarpa Sherff (figs, a-h) 490

Bidens gracilior (0. Hoffm.) Sherff (figs, i-p) 490

Bidens palustris Sherff (figs, a-g) 492

Bidens Taylori (S. L. Moore) Sherff (figs, h-o) 492

Bidens Schlechteri Sherff (figs, a-i) 494

Bidens Hoffmannii Sherff (figs, j-p) 494

Bidens Mildbraedii Sherff 498

Bidens Bequaertii DeWild 500

Bidens Hildebrandtii 0. Hoffm 502

Bidens magnifolia Sherff 504

Bidens Phalangiphylla Sherff (figs, a-h) 506

Bidens Elliotii (S. L. Moore) Sherff (figs, i-p) 506

Bidens insecta (S. L. Moore) Sherff 508

Bidens robustior S. L. Moore 510

Bidens ugandensis (S. L. Moore) Sherff 514

Bidens cinerea Sherff 516

Bidens crocea Welw. ex O. Hoffm. (figs, a-g); var. verrucifera

S. L. Moore (fig. h) 518

Bidens flabellata 0. Hoffm 520

Bidens Baumii (0. Hoffm.) Sherff 522

Bidens Moorei Sherff (figs, a-g) ; var. verrucosa Sherff (figs, h, i) 524

Bidens andongensis Hiern 532

Bidens Buchneri (Klatt) Sherff 534

Bidens somaliensis Sherff 540

Bidens Seretii (DeWild.) Sherff 548

Bidens Stuhlmannii (O. Hoffm.) Sherff 552

Bidens ukambensis S. L. Moore (figs, a-i) 556

Bidens rhodesiana Sherff (figs, j-p) 556

Bidens grandis Sherff 564

Bidens coriacea (O. Hoffm.) Sherff 568

Bidens Crataegifolia (0. Hoffm.) Sherff 572

Bidens kilimandscharica (O. Hoffm.) Sherff 574

Bidens Volkensii O. Hoffm 578

Bidens lineata Sherff 580

Bidens Schweinfurthii Sherff 584

CLXXVIII. Bidens nyikensis Sherff 586

CLXXIX. Bidens Rogersii Sherff 588

CLXXX. Bidens chaetodonta Sherff (figs, a, c-t); var. glabrior (O. & H.

in Oliv.) Sherff (fig. 6) 596

CLXXXI. Bidens Rueppellii (Schz. Bip.) Sherff 598

CLXXXII. Bidens Vatkei Sherff , 600

CLXXXIII. Bidens rotata Sherff 602

CLXXXIV. Bidens Cirsioides Sherff 604

CLXXXV. Bidens Dielsii Sherff 612

CLXXXVI. Bidens Neumannii Sherff 614

CLXXXVII. Bidens ternata (Chiov.) Sherff 616

CLXXXVIII. Bidens setigera (Schz. Bip.) Sherff (figs, j, k); var. abyssinica

(Schz. Bip.) Sherff (figs, a-i) 620

Bidens praecox Sherff (fig. 1) 620

CLXXXIX. Bidens setigeroides Sherff (figs, a-t) 628

Bidens phelloptera Sherff (figs, j-s) 628

PREFACE

It is now a quarter of a century since the work detailed in the
following pages was begun. 1 The genus Bidens was suggested at
that time by Dr. Jesse More Greenman as deserving of monographic
study (c/. my Revision of the Genus Coreopsis, Field Mus. Bot.
Ser. 11 : 279. 1936). Numerous facilities for research and publication
were at once granted by the Department of Botany of the University
of Chicago and by the Department of Botany of the Field Museum
of Natural History. Subsequently, many other institutions of
learning and many individuals throughout the world extended assist-
ance of the most helpful kind. Indeed, it is certain that without
their cooperation my studies could never have been advanced to a
reasonable degree of completion.

The genus Bidens was so closely intertwined in botanical litera-
ture with Coreopsis, Cosmos, Coreocarpus, Megalodonta, Dahlia,
Isostigma, Heterosperma, Thelesperma, and certain other genera
of Compositae, that it became necessary in many cases to make a
truly monographic study of these allied genera before attempting
to progress further in the treatment of Bidens itself. This has occa-
sioned considerable delay in the consummation of the present work
but has permitted the writing of several other revisional texts which
it is hoped will be of compensating value.

It is exceedingly difficult in a work of this kind to describe properly
or to acknowledge completely the innumerable bits of aid received
over so long a time as twenty-five years. Several botanists and
collectors have personally journeyed to distant and often almost
inaccessible places to secure specimens for my studies. Various
teachers of botany have enlisted the aid of their more advanced
students to secure a large assemblage of materials. Most of the
world's larger museums and herbaria have lent their entire collec-
tions of Bidens and related genera or have placed at my disposal
every desired facility when I sojourned with them for herbarium
or library study. One foreign institution even went so far during
the troublous times of the World War as to cut the sheets of type
or other valuable specimens into halves and transmit one half for
the delineation of my illustrative plates. In various articles already

1 At the University of Chicago, where the first stages were completed in the
graduate department. Some of the earliest findings were embodied in a paper
(Studies in the genus Bidens III, Bot. Gaz. 61: 495. 1916) which was accepted by
that institution as a thesis for the Doctor of Philosophy degree.

12 PREFACE

published, some of this assistance has been acknowledged. At this
time, however, I would express my indebtedness and gratitude to
the staffs of all the many cooperating institutions and especially
to the following individuals: Dr. Charles Sprague Sargent (deceased),
former Director, and Miss Ethelyn Tucker, Librarian, Arnold
Arboretum of Harvard University; Dr. Adolph Engler (deceased),
former Director, Dr. Ludwig Diels, present Director, Dr. Robert
Pilger, Associate Director, and Dr. Johannes Mattfeld, Curator,
Botanical Garden of Berlin; Dr. Herbert E. Gregory, former Director,
Dr. Peter Buck, present Director, Mr. Charles Noyes Forbes (de-
ceased), former Curator of Botany, Mr. Edwin H. Bryan, Jr., Curator
of Collections, Dr. Harold St. John and Mr. Francis Raymond
Fosberg, members of the Mangarevan Expedition of, Bernice Pauahi
Bishop Museum; Dr. Robert Chodat (deceased), former Director,
Institute of Botany of the University of Geneva and Boissier Her-
barium; Dr. Alfred Barton Rendle, former Keeper of Botany, Dr.
John Ramsbottom, present Keeper of Botany, and Mr. Spencer
Le Marchant Moore (deceased; for many years affiliated with),
British Museum of Natural History; Dr. Otto Buchtien, formerly
in charge of the Buchtien Herbarium, La Paz, Bolivia; Dr. Emile
DeWildeman, former Director, Dr. Walter Robyns, present Director,
and Dr. P. Staner (until recently Attache at the Museum of the
Belgian Congo at Tervueren but now on the staff of), National
Botanical Garden at Brussels; Dr. Harvey Monroe Hall (deceased),
former Professor of Botany, and Dr. Willis Linn Jepson, Professor
of Botany, University of California; Mr. James Melville Macoun
(deceased), former Curator, Herbarium of Canadian Geological
Survey; Dr. Otto Emery Jennings, Curator of Botany, Carnegie
Museum, Pittsburgh; Dr. John Merle Coulter (deceased), former
Head of Department of Botany, University of Chicago; Dr. Alexander
Borza, Director, Institute for Systematic Botany at the University
of Cluj; Dr. Carl Christensen, Curator of the Botanical Museum,
University of Copenhagen; Dr. Willard Winfield Rowlee (deceased),
former Professor of Botany, Dr. Liberty Hyde Bailey, former Pro-
fessor of Horticulture, and Dr. Karl McKay Wiegand, Professor of
Botany, Cornell University; Mr. Charles Clemon Deam, formerly
owner and custodian of the Deam Herbarium; Mr. Otto Degener,
author of the New Flora of the Hawaiian Islands, owner and custo-
dian of the Degener Herbarium; Dr. Casimir DeCandolle (deceased),
formerly in charge of the DeCandollean Prodromus Herbarium, Dr.
John Isaac Briquet (deceased), former Director, and Dr. Benedict

PREFACE 13

Pierre Georges Hochreutiner, present Director, Delessert Herbarium ;
Dr. Fritz Knoll, former Director, Botanical Institute of the German
University of Prague; Dr. Enrico Carano, former Director, Dr.
Giovanni Negri, present Director, and Dr. Renato Pampanini,
former Adjutante and Conservator, Institute of Botany of the
University of Florence; Dr. Carl Skottsberg, Director, Gothenburg
(Gb'teborg) Arboretum; Dr. Benjamin Lincoln Robinson (deceased),
former Curator, Dr. Merritt Lyndon Fernald, present Curator, Mr.
Charles A. Weatherby, Assistant Curator, Miss Mary Ann Day
(deceased), former Librarian, and Miss Ruth D. Sanderson, present
Librarian, Gray Herbarium, Harvard University; Dr. Edward Lee
Greene (deceased), former owner and custodian, and Dr. Julius A.
Nieuwland (deceased), former Curator, E. L. Greene Herbarium;
Sir David Prain, former Director, Sir Arthur W. Hill, present
Director, Dr. Otto Stapf (deceased), former Keeper of Herbarium,
Mr. Arthur Disbrowe Cotton, present Keeper of Herbarium, and Miss
M. L. Green, Botanist, Royal Botanical Gardens of Kew; Professor
Siro Kitamura, Imperial University, Kioto; Dr. J. W. C. Goethart,
Conservator, National Herbarium (Herb. Rijks), Leyden; Dr.
Benjamin Daydon Jackson (deceased), former General Secretary,
Linnean Society of London; Dr. Wilhelm Ruhland, Director,
Botanical Institute of the University of Leipsic; Dr. Carl Otto
Rosendahl, Chairman of Department of Botany, Dr. Martin
Lawrence Grant, recently Assistant in Botany, and Dr. John
William Moore, Curator of Herbarium, University of Minnesota;
Dr. George Thomas Moore, Director, Mr. Moses Craig (deceased),
former Curator of Herbarium, and Dr. Jesse More Greenman,
present Curator of Herbarium, Missouri Botanical Garden; Dr.
Karl Eberhard Goebel (deceased), former Conservator of the Royal
Botanical Garden, and Dr. Hermann Ross, Chief Conservator of
the Botanical Museum, Munich; Dr. Edwin Bayer, Director of
Department of Botany, National Museum, Prague; Dr. Karel
Domin, Director, Botanical Institute and Gardens of Charles
University, Prague; Dr. Alexander Zahlbruckner, former Custodian,
Dr. Heinrich Handel-Mazzetti, former Custodian, and Dr. Karl
Keissler, Director, Department of Botany, Natural History Museum
of Vienna; Dr. Nathaniel Lord Britton (deceased), former Director,
Dr. Elmer Drew Merrill, former Director, Dr. Marshall Avery Howe
(deceased), late Director, Dr. Henry Allan Gleason, Deputy Director
and Head Curator, Dr. John Hendley Barnhart, Bibliographer,
and Dr. John Kunkel Small, Curator, New York Botanical Garden ;

14 PREFACE

Mr. George Claridge Druce, formerly in charge of the Dillenian
Herbarium, and Dr. Joseph Burtt-Davy, Lecturer in Tropical Forest
Botany, Oxford University; Dr. H. LeComte, Honorary Professor,
Dr. Henri Humbert, Professor, Mr. Louis Anfray (deceased), former
Preparator, and Dr. Paul Danguy, Vice-Director, Museum of
Natural History of Paris; Dr. John Milton Fogg, Jr., Assistant
Professor of Botany, University of Pennsylvania; Dr. Boris Issat-
chenko, former Director, Dr. Boris Keller, present Director, and
Dr. V. P. Savicz, Assistant Director, Botanical Garden of Leningrad ;
Mr. Marcus Eugene Jones (deceased), former Honorary Curator
of Herbarium, and Dr. Philip A. Munz, Professor of Botany, Pomona
College; Mr. Stewardson Brown (deceased), former Curator of
Plants, and Dr. Francis W. Pennell, present Curator of Plants,
Academy of Natural Sciences, Philadelphia; Dr. LeRoy Abrams,
Professor of Botany and Curator of the Dudley Herbarium, and
Dr. Ira L. Wiggins, Assistant Professor of Botany, Stanford Uni-
versity; Dr. Gunnar Samuelsson, Director of the Botanical Section
of the Natural History Royal Museum, Stockholm; Dr. William R.
Maxon, Curator, United States National Museum; Dr. Sidney Fay
Blake, Senior Botanist, United States Bureau of Plant Industry;
Dr. Richard Wettstein-Westersheim (deceased), former Director,
Botanical Garden and Institute of Vienna; Dr. Charles Elmer Allen,
Professor of Botany, and Dr. Norman Carter Fassett, Assistant
Professor of Botany, University of Wisconsin; Mr. William Harris
(deceased), former Superintendent of Public Gardens for the Depart-
ment of Agriculture in Jamaica; Professor Angel L. Cabrera, National
University of La Plata, Argentina; Sr. Jose" F. Molfino, Ministry
of Agriculture, Buenos Aires; Mr. James C. Nelson, Principal,
Senior High School, Salem, Oregon; Mr. F. G. Overlaet, Territorial
Administrator at Kafakumba, District of Katanga, Belgian Congo;
Mr. St. Ahnne, President of the Chamber of Agriculture of Tahiti
in 1916; and Mr. V. Van Straelen, President, Institute of National
Parks of the Belgian Congo, Brussels.

From its inception, most of the work has been done at the
Field Museum of Natural History, where I have been shown in-
numerable courtesies and afforded much valuable aid. It is a genuine
pleasure to express here my gratitude to Mr. Frederick J. V. Skiff
(deceased), former Director, Mr. David C. Davies (deceased),
former Director, Mr. Stephen C. Simms (deceased), late Director,
Dr. Charles Frederick Millspaugh (deceased), former Curator of
Botany, Dr. B. E. Dahlgren, present Curator of Botany, Mr. Paul

PREFACE 15

Carpenter Standley, Associate Curator of the Herbarium, and Mr.
J. Francis Macbride, Assistant Curator of Taxonomy. I desire to
thank also the Board of Trustees of Field Museum and particularly
its President, Mr. Stanley Field.

From time to time since late in 1913, the results of my investiga-
tions in Bidens have been published in various botanical journals,
especially the Botanical Gazette, the American Journal of Botany,
the Journal of the Pan-Pacific Research Institution, the Occasional
Papers of Bernice P. Bishop Museum, and the Bulletin du Jardin
Botanique de L'fitat (Bruxelles). Numerous references to these
journals will be found scattered through the present text. In fact,
to a certain extent this text represents a final consolidation of the
materials presented earlier in some two dozen or more separate
articles. Most of the text stands as it was prepared ten or more
years ago. A sincere attempt has been made, however, to add treat-
ments for all new forms which have come to light recently and to
incorporate, so far as space would permit, additional exsiccatae of
importance and references to the more noteworthy recent literature.

Throughout the preparation of the original manuscript and final
text, I have been aided in the proofreading by my wife, Fern R.
Seeley Sherff. Her cooperation is acknowledged here most gratefully.

Of all the more important specimens cited I have made photo-
graphs, these aggregating probably more than two thousand. Com-
plete sets are in my private collection and in the Herbarium of the
Field Museum of Natural History. A few hundred photographs
have been distributed to certain other herbaria, notably those of
the Berlin Botanical Garden and the National Botanical Garden
at Brussels.

It was originally intended to present delineations of authentic
materials for every known species. Accordingly, until about six
years ago I had sketched all species known to me, and even many
varieties. Since that time, however, the pressure of other work, not
to mention the anticipated limitations of space, has prevented the
preparation of additional plates. Fortunately most of the recently
described species are well represented in herbaria by type and
cotype materials, 1 so that little difficulty should be encountered in
problems of identification.

In general, geographic names are given essentially as in modern
atlases. In a few cases, however, it has seemed wise to leave the

1 The term "cotype" is used throughout to connote a duplicate of the type (i.e.,
a paratype; cf. J. C. Arthur et al., Bull. Torr. Bot. Club 34: 172-174, Apr., 1907).

16 PREFACE

country name as given in my earlier writings; e.g., British East
Africa is retained for Kenya Colony and German East Africa for Tan-
ganyika Territory. 1 In most cases where specimens were described
as having been collected "in the vicinity of" a certain town or city,
these qualifying words have been deleted by the Editor. Moreover,
all altitudes expressed by the collector in feet have been altered in
the process of editing to read in meters, the conversion being made
on the slightly inexact basis of 3^ feet to one meter.

The text has been made to conform throughout to the Inter-
national Rules of Nomenclature as adopted at Cambridge, England,

in 1930 (ed. 3, Jena, 1935). 2

EARL EDWARD SHERFF

1 An unwelcome complication arises in the latter case, in that northwestern-
most German East Africa (that is, Urundi and Ruanda) now appears in atlases as
a part of Belgian Congo. It is quite possible that several specimens recently
collected in "Belgian Congo" came from territory cited by me for earlier specimens
as a part of German East Africa.

2 With the slight exception that Recommendation XL-b, intended to apply
only to "a new specific or other epithet" and governing the construction of posses-
sive names when these are derived from "the name of a man," is made to apply to
old as well as "new" epithets. Thus, for examples, Coreopsis Sereti (original spell-
ing) appears as C. Seretii, and Bidens Eatoni (original spelling) appears as B. Eatonii.
It would seem that, in the interests of nomenclatural simplification and unification,
a future International Congress should amend Recommendation XL, making
part "b" and perhaps the other three parts to apply to old as well as to new epithets.

It may be added here that in the present text Recommendation XLIII of the
International Rules has been followed in accordance with what it seemed must be a
correct literal interpretation, rather than in accordance with the interpretation
placed upon it by most botanists (if we may judge by their practice). This
Recommendation provides that: "Specific (or other) epithets should be written
with a small initial letter, except those which are derived from names of persons
(substantives or adjectives) or are taken from generic names (substantives or
adjectives)." This is essentially the same as Recommendation X of the Inter-
national Rules adopted in 1905 at Vienna, and, curiously enough, the context con-
tains the same flaws that were manifest in the context for the earlier recommenda-
tion. No example is given immediately of a specific name taken from a generic name
and used as an adjective (in "Lythrum Hyssopifolia," perhaps originally intended for
an example, "Hyssopifolia" is the name of a former genus and is used as a sub-
stantive, lacking, quite naturally of course, agreement in gender with Lythrum).
However, elsewhere in the text of the 1930 Rules, specific epithets taken directly
from generic names and used as adjectives are begun with a small letter (e.g., linoides
from Linurn, Art. 69, Examples, line 4). Confronted with this evident disregard of
recommendations by those whose very duty it was to edit and publish them, I have
chosen to ignore all but the literal wording of the recommendation itself as printed.
In this way it is felt that the matured and officially expressed judgment of those
in attendance when the recommendation in question was originally put to a vote
has been given proper recognition. The reader will find, therefore, Bidens Cos-
moides, Bidens Cirsioides, etc., in the text. Moreover, trivial names like geraniifolia,
ferulaefolia, etc., have been construed as coming within the scope of the same
recommendation, hence the names, Bidens Geraniifolia, Bidens Ferulaefolia, etc.

THE GENUS BIDENS

EARL EDWARD SHERFF

HISTORICAL SURVEY OF GENUS

The genus Bidens dates back (if we disregard the genus in so far
as it appeared in the works of Tournefort and other pre-Linnean
writers) to Linnaeus' Species Plantarum (p. 831. 1753) and his
Genera Plantarum (ed. 5. 362, No. 840. 1754). Bidens tripartita L.
was the type. Except for certain species (e.g., B. nivea L., B. verti-
cillata L., and B. fruticosa L.), which since have been universally
recognized as belonging to genera other than Bidens (and, too, other
than Coreopsis; see list of Nomina e Bidente excludenda at end of
this work), the Linnean species of Bidens had achenial awns or aristae,
and these were armed with retrorse barbs.

In 1790, * Necker (Elem. Bot. 1: 86-87) subdivided the genus
Bidens into two new genera. Because of the existence of species
with more than two achenial aristae, he dropped the name Bidens.
He proposed, instead, the names Pluridens and Edwarsia. His
Pluridens was described as having "folia simplicia" and apparently
was meant as synonymous with Bidens L. sensu stricto (although
the Linnean type of the genus Bidens was really B. tripartita L., a
species with compound leaves!). It would include Bidens cernua L.
His Edwarsia was described as having "folia composita" and con-
sisting of "quaed. Bident. Linn." It thus would include, for example,
B. pilosa L. and B. bipinnata L.

In 1794, Moench (Meth. 569 and 595) followed Necker's treat-
ment essentially, but substituted the names Bidens and Kerneria
for Necker's two names. Neither Necker's treatment nor that of
Moench is today accepted by botanists.

About a century ago Gaudichaud (Voy. Freycinet Bot. 464,
pL 85. 1826-1830), describing a species collected in the Hawaiian
Islands during Freycinet's voyage, named the plant Bidens micrantha.
Shortly afterward, Cassini (Diet. Sci. Nat. 51: 475. 1827) called
attention to the curved achenes of Gaudichaud's species. He made
this achenial character the basis for proposing his new genus Cam-
pylotheca (syn. Dolicotheca). Later, Lessing (Linnaea 6: 508. 1831)

1 Cf. E. L. Greene, Pittonia 4: 245. 1901.

18 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

accepted Cassini's genus for species like Bidens micrantha Gaud.,
but erected a new genus, Adenolepis, to include a somewhat different
form, his (Lessing's) A. pulchella. Concerning Campylotheca, how-
ever, we may note that the name was retained by DeCandolle in
his Prodromus (5: 593. 1836), although elsewhere it was accorded
only slight attention. In fact, the collections in those days embraced
so few specimens from the Pacific Islands that little study was made
of the Pacific flora by taxonomists.

DeCandolle (loc. cit.) listed under Bidens proper 76 species. An
essential character of Bidens as distinguished from Coreopsis was,
in his opinion, the possession of retrorse barbs by the achenial
aristae. If these were lacking he referred the species to Coreopsis.
His 76 species of Bidens he divided into three sections. His Sect. I,
Platycarpaea, included such species (as to obovate-cuneiform, ob-
compressed, or flat achenes) as B. tripartite, L., B. connata Muhl.,
and B. cernua L. His Sect. II, Psilocarpaea, included such species
(as to elongate, linear-tetragonal achenes) as B. triplinervia H.B.K.
and B. pilosa L. ; and with these species he even joined those climbing
species like B. Rubifolia H.B.K. and B. squarrosa H.B.K., species
which have elongate, flat, almost ribbon-shaped achenes. His
Sect. Ill, Discopoda, included the one species B. purpurea DC., a
species that was a true Cosmos and later was very properly trans-
ferred to that genus (Benth. & Hook. Gen. PL 2: 387. 1876; cf.
Hemsl. Biol. Centr. Amer. Bot. 2: 200. 1881). It is seen, then, that
the true species of Bidens were in reality divided by DeCandolle
into only two sections, namely, Platycarpaea and Psilocarpaea.
These, however, were distinguished upon a surer morphological basis
than was the case with either Necker or Moench.

Aside from Campylotheca and Bidens, DeCandolle (op. cit. 633)
described a new plant that resembled Bidens, but which appeared
remarkable in having the ligules pistillate and fertile. He created
the genus Delucia therefor, and his new plant he named D. Ostru-
thioides (later Schultz Bipontinus in Seem. Bot. Voy. Herald 308.
1852-1857 renamed the species Bidens Ostruthioides, and this latter
name has been widely accepted ever since). Nuttall, in 1841 (Trans.
Amer. Phil. Soc. n. ser. 7: 368), reduced Campylotheca to the rank
of a section under Bidens, but did not give extended reasons for so
doing. His attention had been directed to the subject by his having
traveled among the Hawaiian Islands and discovered there at least
one new species of Bidens (his B. gracilis}. Nuttall, however, did
evince a rejection of Cassini's main character for Campylotheca,

THE GENUS BIDENS 19

namely, the curved or twisted achenes. He worded his description
to read "sometimes curved or contorted," and for one species (his
B. mutica) he definitely described the achenes as "straight." Since
Nuttall's time, we may add, many other closely affiliated species
have been discovered, including forms of Bidens micrantha itself,
which have straight achenes, thus bringing the curved-achene
character into discredit.

In 1856 Schultz Bipontinus undertook the determination of
various specimens collected on the Island of Nukahiva (Marquesas
Islands) by Edward Jardin. Finding four new species native to this
single small island, Schultz Bipontinus appears to have entered upon
a very careful and painstaking research into the subject of their
generic affinities, finally publishing his results 1 in Flora (39: 357.
1856). As regards the maintenance of a genus Campylotheca apart
from Bidens, he was unreservedly against such a course. His four
new species from Nukahiva and all of the Hawaiian species he
referred to Bidens.

In 1861, Asa Gray (Proc. Amer. Acad. 5: 125-128) made the
next important contribution to a knowledge of the group. Gray
had received from the Museum of Natural History in Paris several
specimens collected by Jules Remy in the Hawaiian Islands, also
a number from the United States Exploring Expedition under
Captain Wilkes, collected in the Hawaiian Islands, Tahiti, Eimeo,
and elsewhere in the Pacific. Most of these were new species. Gray's
publication indicates that he was probably unaware of Schultz
Bipontinus' paper. Thus, for example, he inadvertently created the
name Coreopsis Macraei for a plant already named by the latter
Bidens Campylotheca. As, therefore, he does not seem to have read
Schultz Bipontinus' paper, it is all the more interesting and valu-
able to find that Gray, too, was compelled to abandon the name
Campylotheca. Species having the achenes wingless and the awns
retrorsely barbed he described under Bidens. But several other
species, different in having either exaristate achenes or even winged
achenes, he described under Coreopsis. Thus he described Bidens
hawaiensis, B. Lantanoides, Coreopsis mauiensis, C. macrocarpa, C.
Macraei, C. Cosmoides, and C. Menziesii. Gray's own words at the
time of describing some of these species are worthy of note.
Speaking of the futility of maintaining Campylotheca as a separate

1 For a personal estimate, apparently unbiased and accurate, of the taxonomic
ability and sagacity that Schultz Bipontinus displayed at times, see Bentham,
Journ. Linn. Soc. 13: 340. 1873.

20 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

genus, apart from Bidens and Coreopsis, he said: "Its adoption
merely gives us three limitless genera unmarked by any peculiarity
in habit, in the place of two artificially separated ones. . . . Vain is
the attempt to draw absolute limits where Nature luxuriates in
gradations" (Proc. Amer. Acad. 5: 126. 1861).

In 1888 there appeared the posthumous Flora of the Hawaiian
Islands by William Hillebrand. From his twenty years of resident
study in the Hawaiian Islands and his careful investigations subse-
quently, Hillebrand was eminently well versed in their species. His
treatment assumes almost the aspect of a monographic revision,
and it is evident that he possessed much more than an ordinary
knowledge of Bidens and related groups. His brilliancy, however,
appears to have been manifested, as is so apt to occur with a local
botanist, less in the excellence of his genus concept than in that of
his species concept. And, even in the latter respect, his generaliza-
tions are often necessarily faulty because of the inadequacy of his
material. Hillebrand, like Gray, appears never to have seen Schultz
Bipontinus' paper. He discarded Gray's treatment, however, and
adopted once again Cassini's name Campylotheca. Speaking of
Campylotheca he says (p. 211) : "The genus, as it presents itself now,
stands evidently nearer to Bidens than to Coreopsis, and might be
merged in the former if it were not for the winged achenes of so many
species, 1 which, if admitted in the character of Bidens, would efface
the limits between that genus and Coreopsis." Gray's Hawaiian
Bidens is transferred by Hillebrand to Campylotheca. 2

From early times down to and including the work of Drake del
Castillo, botanists, as exemplified by Augustin DeCandolle (the
DeCandolle who is meant throughout this work except where noted
to the contrary) and Asa Gray, tended to refer to Bidens those species
with retrorsely barbed awns, and to Coreopsis those species with
antrorsely barbed awns or with awns inconspicuous. 3 But, from
time to time in North America, new forms have been discovered,
identical in each case with a certain species of Coreopsis (as then

1 Regarding the inaccuracy of this statement, cf. footnote 1, p. 24.

2 We may note at this point that shortly following Hillebrand's book, Drake
del Castilld (Illustr. Fl. Ins. Mar. Pacif. 208-210. 1890) transferred all the Campy-
lotheca species, also several allied species of Bidens, to the genus Coreopsis!
Strangely, however, he left such species as Bidens Lantanoides Gray and B. australis
Spreng. (B. paniculata Hook. & Arn.) in Bidens.

3 It is true that in isolated cases species with retrorsely barbed achenes were
put by Jacquin (e.g., Bidens Ferulaefolia), by Loureiro (e.g., B. leucorrhiza) , by
Cavanilles (e.g., B. Sambucifolia), and by others into Coreopsis. In each such
case, however, these species were sooner or later transferred to Bidens and there
retained by the great body of taxonomic workers.

THE GENUS BIDENS 21

delimited) or Bidens except in the direction of the barbs on the
awns. Asa Gray (cf. Fernald, Rhodora 15: 77. 1913), when con-
fronted with such a form of "Coreopsis aristosa Michx." (the then
accepted name), designated it "C. aristosa inBidentem transformata."
Later (Syn. Fl. N. Amer. 1, pt. 2: 294-296. 1884) he treated this
and similar forms as hybrids between Coreopsis and Bidens.

In 1893, Britton (Bull. Torr. Bot. Club 20: 280-281), emphasizing
the instability of the barb-direction character f or Bidens frondosa L.,
and also separating the two genera on general grounds rather than
by one particular character, transferred six species from Coreopsis
to Bidens. The validity of these transfers has since been accepted
unhesitatingly by all prominent American botanists who have
critically studied the Eastern United States species of Bidens, among
them Wiegand (Bull. Torr. Bot. Club 26: 401. 1899), Greene (e.g.,
Leafl. Bot. Crit. 1: 200. 1906), 1 and Robinson and Fernald (Gray's
Man. ed. 7: 839. 1908). It is also implied by many other botanists
working upon the species of other regions but following the same
distinctions, a singular case being that of Brandegee's description
(Zoe 5: 239. 1906) of Bidens alpina and Greenman's description
(Proc. Amer. Acad. 41: 264. 1905) of Bidens sarmentosa. The achenes
are described for B. alpina as "nearly smooth; awns none or two
varying from 1 mm. long to rudiments, corneous and not barbellate";
for B. sarmentosa, as "glabrous or sparingly hispidulous, awnless
or with reduced awns." But, on investigation, these species were
found to be identical; in turn, B. sarmentosa, which from priority
of publication would otherwise stand as the accepted species, was
found to match in every character Coreopsis Anthemoides DC.,
having achenes described (DC. Prodr. 5: 573. 1836) as "(immaturis)
linearibus glabris brevissime bidentatis." Thus, a species placed
by DeCandolle in Coreopsis, evidently because of its very short
awns, was independently referred by Brandegee and by Greenman,
about 70 years later, to Bidens, evidently because the achenes lacked
wings and the general characters coincided closely with those of
certain unquestioned species of Bidens (e.g.,B. triplinervia, especially
its var. macrantha, with awns retrorsely barbed). More recently
still, specimens of this same species have been found with most of
the achenial aristae retrorsely barbed, and one such form has been
described as Bidens Purpusorum Bitt. & Ptsn. (cf. Sherff, Bot. Gaz.
76: 153. 1923).

1 Thus, Greene refers to Bidens a plant ("B. tenuissima") with "erect, up-
wardly barbed awns."

22 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

Fernald, in a recent discussion of the awn characters of Bidens
(Rhodora 15: 74-78. 1913), lists no fewer than six American species
in which occurs a more or less pronounced form having the awns
barbed in the reverse from the normal direction. Thus, for example,
Bidens connata Muhl. has awns retrorsely barbed, while var. anomala
Farw. has awns antrorsely barbed. Again, Bidens aristosa (Michx.)
Britt. has antrorsely barbed awns, while the var. Fritcheyi Fern, has
retrorsely barbed awns. Hence it is obvious that, were the old artifi-
cial method of distinguishing between Coreopsis and Bidens (namely,
by the direction of the barbs on the awns) to be retained, an anoma-
lous situation would result. We should be compelled either to regard
each of these varieties as a hybrid between two species of distinct
genera, a course certainly unwarranted in several cases (cf. Fernald,
loc. cit., and Wiegand, Bull. Torr. Bot. Club 26: 401. 1899), or to
refer each variety to the other genus, an entirely indefensible alterna-
tive. We are compelled, then, to view these varieties, in at least
the majority of cases, as merely more or less distinct and pronounced
forms of their respective species. This being true, the awn character
method of separating Coreopsis from Bidens is seen to demand a
restatement. In the light of my own monographic researches upon
these two genera, we may go only so far as to say that all forms with
retrorsely barbed achenial aristae belong in Bidens, but that forms
having antrorsely barbed aristae or having no aristae at all may
belong in either Bidens or Coreopsis, depending upon various other
considerations. 1

The somewhat superficial study made by Greene (Pittonia 4:
242-270. 1901) upon several species of Bidens may be noted here
in passing. Greene commented upon the dissimilarity between
such species as B. cernua L. and B. tripartite^ L. Even so radical a
botanist as he, however, refrained from proposing a generic segrega-
tion of the B. cernua forms. Nevertheless, Greene did segregate the
aquatic Bidens Beckii as the type of a new genus, Megalodonta;
and, when the peculiar achenes of this species are considered, it
seems wise to accept Greene's new genus as valid.

Strangely enough, no one appears to have tried to segregate
generically the pronounced and well defined group of Bidens species
typified by B. reptans (L.) G. Don. 2 These species differ from the

1 For additional notes on the aristal barbs, see Wegener, Beih. Bot. Centralbl.
31: 79. 1914; etiam Briquet, Arch. Sc. Phys. Nat. 42: 65. 1916.

2 DeCandolle (Prodr. 5: 599. 1836), however, did create the name Bidens
Coreopsidis for one of these species. Even earlier, the names Coreopsis reptans L.,
C. incisa Ker., etc., had been given to certain of these species, but without very
serious consideration's being given to their generic affiliations.

THE GENUS BIDENS 23

more typical species in being climbers, and in having long, flat
achenes that are hispid along the two edges in such a way at times
as to suggest a centipede. They are referred in this work to the
Section Greenmania. Similarly, the anomalous Bidens clarendonensis
Britton may be mentioned here. It has trailing, somewhat woody
stems, thick, rhombic-ovate leaves, and by some might be inter-
preted as representing a new genus (although by me it is taken as
representing the monotypic section Neurophyllum).

It is seen that, if we accept the narrow concept of Bidens held
by Cassini, Lessing, and Hillebrand, and seek to segregate the native
Pacific species under the name Campylotheca, to be consistent we
shall have to subject the entire genus Bidens to a process of subdivi-
sion and segregation, resulting in at least eight genera. There are
at least two good reasons for not adopting such a course. In the
first place, the accuracy of such a series of interpretations is not so
well established as to justify overturning almost the entire nomen-
clature of the genus. In the second place, the lines of demarcation
among the various subordinate groups are so fluctuating and in-
constant that efforts to apply a binomial system of nomenclature
to the many species would be rendered even more difficult than
before. I am constrained to reject, therefore, any idea of seriously
interfering with the general status of Bidens. Cassini's name
Campylotheca I am compelled to reject. 1

1 In taking this step it is reassuring to read the words of so eminent a student
of the Compositae as Bentham. Speaking of Cassini and his work, he stated
(Journ. Linn. Soc. 13: 338. 1873): "Unfortunately, however, in working out the
details of the genera in the 'Dictionaire,' he indulged in an enormous and useless
multiplication of generic names, which only tended to throw the nomenclature
into confusion, and cast a slur upon all his labors. Wherever he observed a slight
difference in the involucre, pappus, or general aspect, or could not readily identify
an imperfect specimen, an engraved figure, or a description often incorrect, he
at once set it down as a new genus, and has thus, more than any other botanist of
equal ability, overloaded the science with useless synonyms. So recklessly, indeed,
did he give way to this mania of coining new names, that he on many occasions
proposed two, or even three, for the same genus, leaving future botanists to take
their choice." Cassini did not neglect Campylotheca in this respect. At the very
outset he proposed Dolicotheca as an alternative name. This latter name, however,
was never adopted by Lessing, DeCandolle, or others.

We may note here that recently Brown (Forest B.H., Fl. S.E. Polynesia
3: 350. 1935; Bishop Mus. Bull. 130: 350. 1935) has retained Campylotheca and
advanced various queries as to the presence or importance of certain diagnostic
characters hitherto relied upon or hitherto neglected. On the other hand, Degener
(in numerous names published conjointly with myself in past articles cited in
the following pages), Grant (in such names as Bidens orofenensis, B. glandulifera,
B. aoraiensis, etc., published or repeated in this volume with his cooperation),
J. W. Moore (Bish. Mus. Bull. 102: 46. 1933), St. John (in many herbarium
determinations), Skottsberg (Medd. Goteborgs Bot. Tradgard 10: 191. 1935),
and various other able students of the Pacific floras have inclined toward outright
reduction of Campylotheca to Bidens.

24 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

Having laid aside the name Campy iotheca, we must note next
the lack of absolute uniformity in even one distinctive character
among the numerous species of Bidens and of the allied genus
Coreopsis. In spite of this lack, however, one such character does
persist to a considerable extent, especially among the African and
North American (as contrasted with the South American) species.
It is the presence (in Coreopsis) or absence (in Bidens) of two lateral
wings upon the mature achene. In cases where other criteria are
absent, it appears to offer the only logical basis of distinction. This
presence or absence of achene wings was given great weight by Gray,
but in the Pacific flora the wing character is unreliable, and will
lead, if absence of wings be demanded from all species of Bidens,
to an arbitrary and unnatural arrangement. Some three or four
Hawaiian forms commonly have accessory awns or barbs below the
achene's apex, and either these or the principal awns frequently
are decurrent along the achenial edges as a more or less thickened
margin or even as a wing; or at times the awns seem unrelated to
the wings. In Bidens mauiensis, these wings are very conspicuous.
The number of Hawaiian species that exhibit this character, however,
is very small compared with the remaining Pacific species that lack
it. 1 Moreover, a study of their other characters, such as odor of
bruised foliage (when fresh) and shape of ligules, as well as range
of distribution, shows them to be much closer to the wingless-achened
Bidens species of the Pacific than to the American species Coreopsis
lanceolata L., which has winged achenes and which must be taken as
the type of the genus Coreopsis. It seems wise, therefore, to treat such
species as belonging in Bidens instead of in Coreopsis, where placed
by Asa Gray. We shall have even then no greater incongruity in
Bidens than must perforce be tolerated in Coreopsis. Thus, for
example, all authors who have dealt with the subject have retained
the North American wingless-achened Coreopsis rosea Nutt. and
C. tinctoria Nutt. in Coreopsis despite their anomalous achenes,
because their other characters clearly indicated a closer affinity with
Coreopsis than with Bidens. Manifestly this was the only correct
course to pursue, and my own procedure is precisely comparable.

On reference to recent descriptions and types of African species
of Bidens, we find that in several cases the awns, even on achenes
of the same head, are barbed both antrorsely and retrorsely. Thus,

1 Cf. Hillebrand's misleading words, "the winged achenes of so many species."
Doubtless Hillebrand was recalling many specimens of a few species, and unguard-
edly referring to them as "so many species." Reference to his individual descrip-
tions shows few of the species to be described as wing-achened.

THE GENUS BIDENS 25

for example, Moore (Journ. Linn. Soc. Bot. 37: 322. 1906) created
the name Bidens ambigua for Gossweiler 1189, for the very reason
that some of the awns are smooth, others antrorsely barbed, and
others retrorsely barbed ("achaeniis .... aristis 2 quam se ipsa
brevioribus dentibus perpaucis nunc erectis mine recurvis onustis
vel etiam omnino calvis . . . ., hence the trivial name"). Yet in the
same year (Journ. Bot. 44: 22. 1906) he likewise somewhat arbi-
trarily created the name Coreopsis Taylori for a plant showing the
same variation (coll. W. E. Taylor, Jan. 5, 1886; "achaeniis ....
apice setuloso-ciliatis calvis vel aristulis 1 vel 2 brevissimis erecto- vel

patenti- vel etiam recurvo-uncinulatis onustis saepe vero nudis ;

indeed, the plant might almost as well be considered a Bidens, but
the habit is that of Coreopsis"). In referring the latter species to
Coreopsis, he relied mainly upon its habital similarity to other
(so-called) species of Coreopsis from Africa. But, as will be seen
presently, some of these species belong in reality to Bidens. There-
fore, this habital similarity, affording formerly an apparently good
reason for the name Coreopsis Taylori, can no longer be given much
consideration.

The present writer, in bringing together the numerous species
of Bidens for monographic treatment, has come to adopt fully the
distinctions between these two genera as followed by recent American
botanists. In brief, the genus Coreopsis is maintained primarily
because of the peculiar habit and winged achenes of the Linnean
type species (excluding C. alba, C. Bidens, and C. alternifolia, Sp.
Plant, ed. 1. 907-909. 1753; cf. Britton, Bull. Torr. Bot. Club 20:
280. 1893).

Similarly, the genus Bidens is maintained primarily because of
the peculiar habit, strongly barbed awns, and wingless achenes of
several of the Linnean species of Bidens.

MORPHOLOGY, HISTOLOGY, CYTOLOGY, ECOLOGY,
AND OTHER SPECIAL LINES OF INQUIRY

No attempt can be made here to survey completely the work done
so far upon Bidens in the several special fields of plant research. 1

1 Aside from references to Frank's finding of connecting bundles in Bidens (Bot.
Zeit. 1864: 154 and 382. 1864; cf. DeBary, Comp. Anat. Phan. Ferns 308. 1884)
and to Hanstein's finding of transverse girdles in B. cernua and B. tripartite^ (Abh.
Berl. Acad. 1857: 77. 1857; cf. DeBary, op. cit. 297), my manuscript includes
little of value connected with the morphology or histology of the stem or branches.

The morphology of the chaff scales and involucral bracts of the European
species of Bidens has been studied by Briquet (Arch. Sc. Phys. Nat. 43: 333. 1917).
A summary of his findings, as presented elsewhere (Briq. & Cavill. Fl. Alp. Marit.

26 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

Nor can an attempt be made to summarize the environmental con-
ditions under which the numerous species live. These are so varied,
ranging from almost extreme hydrophytism 1 to almost extreme
xerophytism, that habitat data can best be and are presented in
association with the Specimens examined. 2 There, too, will be found
special notes on any uses for medicines, dyestuffs, beverages, etc.,
that various collectors have recorded. There is practically no litera-
ture upon the cytology or genetics of Bidens. 3

6: 215. 1917), is quoted verbatim: "Enfin, une autre particularity tres inteiessante
de nos especes du genre Bidens consiste dans le fait que les bractees involucrales
internes et externes ont une structure tres differente. IndSpendamment de nom-
breux caracteres distinctifs de detail, les canaux s6creteurs sont lies aux faisceaux
dans les premieres (dans la nervure m6diane, il y a 2 canaux phleotermiques et
un canal sur la face ventrale de 1'endoxyle), dans les secondes les canaux sont
beaucoup plus volumineux et places dans le m&ophylle en dehors des faisceaux.
Les bractees paleales presentent les principaux caracteres des bractees involucrales
internes, mais avec une forme differente et une reduction dans le nombre des
faisceaux et des canaux."

The alternation of calyx projections (achenial aristae), corolla lobes, and
stamens in the abnormally tetramerous disc florets of B. cernua has been noted
by Buchenau, also by Wydler (see p. 302, footnote 1).

The achenes' internal structure was investigated for various Compositae by
Hanausek (Ber. Deutsch. Bot. Gesellsch. 20: 449. 1902; Sitzungsber. Konigl.
Acad. Wiss. Wien, Math.-Naturw. Kl. 116: (Abt. 1) 3. 1907; Wiesner-Festschrift
139. 1908; Denkschrift Konigl. Akad. Wiss. Wien, Math.-Naturw. Kl. 87: 93-142,
pis. 1-3. 1912). For Bidens bipinnata, B. tripartite,, B. abyssinica, etc., as for certain
other Compositae (e.g., Helianthus annuus), he found the pericarp to have a
"coal-depositing" layer. This and related facts are summarized by Briquet and
Cavillier (Fl. Alp. Marit. 6: 214. 1917), who state as follows: "La section trans-
versale de 1'akene des Bidens est rhomboidale; Tepicarpe n'est pas cristallifere
et ne porte point de trichomes autres que les aculeoles; sous 1'epicarpe se trouve
un hypoderme a elements etires radialement en palisades, hypoderme simple
par places, plus souvent multiple, dont les parois internes (en contact avec le
scle>ocarpe) transforment leur lamelle mitoyenne (mitoyenne avec le sclerocarpe)
en un epais depdt de charbon (ligne d'un noir fuligineux continue en coupe trans-
versale entre 1'hypoderme et le sclerocarpe) ; le sclerocarpe forme une cuirasse con-
tinue, e'paisse de 2-3 assises, a stereides externes pourvues d'asperites en brochette
faisant saillie dans le depdt de charbon; les faisceaux sont encastres dans la region
interne du sclerocarpe, leur xyleme 6tant enyeloppe par le leptocarpe parenchy-
mateux; 1'endocarpe ne presente rien de particular; 1'albumen possede des parois
cellulaires souvent cplorees en violet; le plan de symetrie de 1'embryon coincide
avec le plan de symetrie de la fleur: les cotyledons sont transversaux."

1 The truly aquatic Bidens Beckii Torr. is here excluded from the genus, in
accordance with the treatment of E. L. Greene, who renamed it Megalodonta
Beckii (Pittonia 4: 271. 1901).

2 We may note in passing, however, a cultural experiment by H. B. Guppy
(Studies in Seeds and Fruits 445-446. 1912) upon Bidens cernua andJB. tripartita,
"two species that grow in wet stations by the sides of ditches, ponds, and rivers.
After three generations the height of the plants was reduced from 17 or 18 inches
to 5 or 6 inches, the fleshy stems becoming dry, woody, and wiry, the length of
the achenes being reduced by half." In young plants of B. cernua, Guppy was
able (op. cit. 480-482), by withholding water, to produce an approach in leaf
outline to that of B. tripartita.

3 Lawrence, writing on "The genetics and cytology of Dahlia species" (Journ.
Genetics 21: 125-159. 1929), cites (p. 151) his own root tip count for the somatic
number of chromosomes in Bidens atrosanguinea "as approximately 48, which was

THE GENUS BIDENS 27

Certain studies have been made, however, upon the flowering
and fruiting heads, having to do chiefly with protection and pollina-
tion, which studies may be mentioned here:

Protection of pollen. Hansgirg (Pflanzenbiolog. Untersuch. 122-
123. 1904) lists five types of antipluvial ("regenscheuer") flowers,
the protection of whose pollen rests upon a phytodynamic principle.
As illustrating his third type, characterized by a standing upright
of the flowers or heads in pleasant weather and by their drooping
over (due to a flexure of the axis) in rainy weather, he mentions,
among other genera, Bidens. (See also B. Volkensii, next paragraph.)

Insect visits. Robertson (Trans. Acad. Sci. St. Louis 6: 473-
474. 1894) made a study of insect visits to plants of B. aristosa on
fourteen days, Aug. 2 to Sept. 15, in the neighborhood of Carlinville,
Illinois. He presents lists of Hymenoptera, Diptera, Lepidoptera,
Coleoptera, and Hemiptera which he observed. On Sept. 20 he
studied the insect visits, in the same neighborhood, to "B. chrysan-
themoides Michx." (as this species does not grow in Illinois he
clearly meant B. cernua). There he found represented all the above
groups but Hemiptera. Scott Elliot (Ann. Bot. 5: 357. 1891), in
his notes on the fertilization of South African and Madagascar
flowering plants, recorded a visitation of B. pilosa by Pieres hellica.
Knuth (Bot. Centralbl. 49: 301. 1892) reported the visit at Kiel,
Germany, of Lucilia cornicina to B. cernua. He later (Blutenbiol.
2, pt. 1 : 598-599. 1898) recorded also the visit of Bombus terrester
to the same species, and cited as well a visit by the honey bee which
had been recorded by H. Miiller. For B. tripartite,, Knuth reported
MacLeod's observation of the bees Bombus and Anthrena visiting
the flowers; he recorded also his own observation of three hoverflies
and one bug. William Saunders, of London, Ontario, reported
insect captures (Canad. Entomologist 11: 196. 1879; also, Amer.
Entomologist 1880: 75. 1880) by a species of Bidens, in all probability
B. cernua. "The insects which he had observed thus captured were
Dipterous [flowerflies, of the genus Syrphus], all of whom had been

later confirmed by a pollen mother cell count of 24. Considerable irregularity of
the divisions was apparent and multiple association was also marked." He records
his unsuccessful attempt to cross B. atrosanguinea with Dahlia Merckii. We
must observe, however, that B. atrosanguinea is a true Cosmos and thus can not
represent Bidens.

The same writer wrote elsewhere (in lit., October 21, 1931) : "It is a remarkable
fact but, with the exception of Bidens atrosanguinea, not a single species of Bidens
or Coreopsis has been examined cytologically as far as I am aware. ... I have
little doubt that these genera are mainly polyploid. One would expect to find
multiple series of chromosomes as in Chrysanthemum and Senecio, but of course I
have no evidence for this view."

28 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

caught by the mouth; some were found dead, others still living, but
unable to withdraw their proboscis." On the other hand, Meehan
(Proc. Acad. Nat. Sci. Phila. 1891: 271. 1891) recorded his invariable
failure, throughout two years of repeated observations, to find one
instance of insect visitation for B. frondosa. He advanced the
opinion that the long; retrorsely barbed achenial aristae had exerted
a deterrent influence on the insects. He furthermore ventured the
assertion that B. frondosa has in no way suffered "by ages of pure
in-and-in breeding." Hansgirg, in the work already cited (p. 133),
lists various myrmecophobic plants. He includes B. Volkensii along
with the common dandelion, Taraxacum palustre var. vulgar e (Lam.)
Fern. (T. officinale Weber), as having reflexed outer involucral
bracts, this tending to prevent access of ants to the flowers.

Protection of flowering heads when young. Gressner (Flora 69:
94. 1886) investigated the developing involucre for two species of
Compositae. He states for B. tripartita (as translated) : "The edge
of the bracts of the involucre of the very young inflorescence possesses
no indentation but, instead, at fairly regular distances apart,
several-celled trichomes. These have stiff, strongly cuticularized
walls and are bent hook-like. . . . The outer surface of the cell
wall shines forth through the delicate strip of cuticle, beautifully
ornamented. Through the inter-hooking of these marginal trichomes
there is obtained an exact enclosure of the bud. Later, as it seems,
the hair-structure in question is broken asunder; the bracts of the
matured involucre are twisted in an extremely irregular way, and
a mass of many-shaped, several-celled trichomes surrounds the
disrupted bract apex."

Anthers and style at anthesis. Cassini (Opuscul. Phytolog. 1:
31. 1826) and, much later, Friedrich Hildebrand (Geschlechtsver-
haltnisse Compos. 66. 1869) described and illustrated the surface
of the style branches for B. tripartita. To translate from Hildebrand :
"The extreme apex [of each style branch] possesses a fascicle or
tuft of sweeping-hairs and somewhat deeper down, separated by
a smooth flat surface from the upper hair-cluster, still a second
sweeping-hair region occurs." Knuth (Blum. Insekt. Nordfrieschen
Inseln 88. 1894; Blutenbiol. 2, pt. 1: 598. 1898) described the behavior
of B. tripartita at and following anthesis rather minutely. To
translate: "Ray flowers almost constantly lacking. 1 Cross section

1 Here we may note Thuillier's surprising and erroneous statement (Fl. Par.
ed. 1. 232. 1790), that there occur sometimes one or two imperfect florets "a la
circonference de la feuille." In his second edition (p. 422. 1799) he corrected
"feuille" to read "fleur."

THE GENUS BIDENS 29

of the head at most 1 cm. The sweeping-teeth at the apex of the
style are somewhat long, those following thereafter are shorter,
the lowermost the longest. They sweep the pollen forward out of
the anther cylinder, whereupon the latter withdraws entirely into the
corolla tube. Then the stigma branches unfold their papillose inner
surface, while meantime the heretofore widely spread corolla lobes
become again somewhat erect and the backwardly barbed calyx
teeth spread away from each other, so that the cross section of the
head above becomes finally 2.5 cm. The originally yellow flowers
become colored toward the end of the blooming-period an unsightly
brown." In his Bliitenbiologie (p. 599), Knuth treated also of
B. cernua, citing H. Miiller for various details. To translate:
"About a hundred flowers compose a head. Each disk flower
possesses, according to H. Miiller, an approximately 1.5 mm. long
tube and an almost equally long, 1 mm. wide bell or limb. Out of
this there arises at the first of the flowering period the anther tube,
covered with pollen and about 1 mm. thick; in the later part of the
flowering period, moreover, the 1 mm. long style branches spread
apart. The structure of these accords quite well with that of the
foregoing B. tripartite,. The stigma papillae are so broad that light
pollen grains of the same flower remain fast upon the edge, so that
here, as also with the foregoing species, spontaneous self-pollination
is made possible." We may note also that Meehan (Proc. Acad.
Nat. Sci. Phila. 1893: 303. 1893) meanwhile had made a study of
anthesis in B. bipinnata and reported it to be essentially the same as
for Heliopsis laevis: "The style pushes up the staminal tube, starting
at nightfall. During the next day the pollen is pressed through the
divisions of the incurved staminal appendages, the style branches
protrude the following nightfall, the staminal tube retires the next
day, followed the following day by the retreating style." 1

Genus BIDENS: Descriptio 2

Linn. Sp. PI. 831. 1753 (maxima ex parte) ; Gen. PI. ed. 5. No.

840. 1754.

Plantae (familiae Compositarum) herbaceae vel fruticosae, annuae
vel perennes, erectae vel procumbentes vel etiam scandentes, glabrae
vel pilosae; caulibus teretibus vel angulatis, plerumque striatis.

1 Under the title "Beitrage zur Entwickelungsgeschichte des Pistills" Buchenau
(Linnaea 25: 622-633. 1852) gives a detailed account of pistil development in the
related Coreopsis bicolor Bosse (verisimiliter C. tinctoria Nutt.).

2 Regarding the gender of the wordBidens, I quote from Briquet and Cavillier
Fl. Alp. Marit. 6: 215, footnote 1. 1917: "Linne Sp. ed. 1, p. 831 (1753) a introduit
dans la nomenclature botanique moderne un nom generique/eraimw. Independam-

30 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

Folia principalia opposita vel rarissime ternata, Integra vel dentata
vel incisa vel semel bis terve ternatim pinnatimve dissecta ; superiora
interdum alterna. Capitula nunc mediocria vel majuscula ad apices
ramorum vel in dichotomiis solitaria, nunc minora numerosiora
irregulariter corymboso-paniculata; nunc heterogama, radiata, flori-
bus radii 1-seriatis neutris vel rarius pistillatis, disci hermaphroditis
fertilibusque, nunc radio deficiente homogama. Involucrum saepius
campanulatum vel subhemisphaericum, bracteis plerumque 2
(rarius 3-4) -serialibus, basi saepe breviter (rarissime dimidio)
connatis, exterioribus saepius herbaceis nunc brevibus nunc in folia
elongata (raro etiam decomposita) expansis, interioribus plerumque
membranaceis saepius hyalino- vel flavido-marginatis. Flores
ligulati plerumque albidi flavive rarius rubri, lamina patente integra
vel saepius denticulata. Paleae angustae, subplanae, flores herma-
phrodites subtendentes. Flores disci corolla regulares, tubulosi,
limbo cylindraceo urceolatove raro 4- plerumque 5-fido. Antherae
basi integrae vel auriculis parvis muticis sagittatae. Styli floris
hermaphroditi rami superne hirti, appendicibus brevibus acutis
vel longioribus subulatis superati. Achaenia a dorso compressa
vel 3-4-gona, obovato-oblonga vel cuneata vel plus minusve linearia,
glabra vel pilis brevibus (his e tuberculis interdum ortis) sursum
vel rarius retrorsum spectantibus ciliata vel conspersa, marginaliter
rarissime tuberculato- vel submembranaceo-alata, apicaliter aequalia
vel attenuata nee distincte vel raro rostrata, nunc exaristata nunc
ad vel sub apice ipso aristis 1-8 rigidis plerumque persistentibus
plus minusve (antrorsum retrorsumve) barbellatis vel aculeolatis
rarissime ad glandulas parvas reductis munita.

SECTIONES GENERIS
No fewer than fourteen sections may be recognized. 1 These are:

Sect. I. Campylotheca (Cass.) Nutt. Trans. Amer. Phil. Soc.
ser. II. 7: 368. 1841 (pro genere, Cass. in Diet. Sci. Nat. 51:
475. 1827). Adenolepis Less. Linnaea 6: 510. 1831 (pro genere).

ment du fait que les noms de genre peuvent etre arbitraires (Regies nomencl.
art. 24), les termes bidens, tridens, etc., etaient employes en latin non seulement
comme substantifs masculins, mais aussi comme adjectifs: Bidens (sous-entendu
Herba) tripartita est done correct, mSme au point de veu du purisme, qui N'est
pas le n6tre. Les expressions Bidens tripartitus, cernuus, etc., doivent etre rejetees."

!Sect. Discopoda DC. (Prodr. 5: 604. 1836)=Cos/nos, sect. Discopoda (DC.)
Sherff, Field Mus. Bot. 8: 430. 1932.

Sect. Hydrocarpaea A. Gray (Syn. Fl. N. Amer. 1, II: 298. l&M) = Megalodonta
Greene, Pittonia 4: 271. 1901.

Sect. Adenolepis (Less.) O. Hoffm. in Engler & Prantl (Pflanzenf. 4, v: 245.
1894)=sect. Campylotheca (q.v.).

THE GENUS BIDENS 31

Adenolepis (Less.) 0. Hoffm. in Engler & Prantl, Pflanzenf. 4, V:
245. 1894 (pro sect. Bidentis). Nos. 1-59.

Demum plerumque fruticosae, saepissime glaberrimae, suci odore
carotae plus minusve similes. Capitula saepius numerosa, radiata.
Achaenia recta vel torta, saepius biaristata aristis plerumque
retrorsum hamosis. Plantae insularum Oceani Pacifici. (Type,
B. micrantha.)

Sect. II. Degeneria Sherff, Bot. Gaz. 93: 213. 1932. No. 60. 1
Genitalia praesertim stylo longissimo valde exserta. (Type, B.
Cosmoides.)

Sect. III. Neurophyllum Sherff, op. cit. 214. No. 61.
Herbae perennes, procumbentes, foliis crassioribus, perspicue
nervatis. (Type, B. clarendonensis.)

Sect. IV. Clomtonia Sherff, loc. cit. No. 62. 2
Frutices, foliis oblongis, acuminatis, etc. Cum characteribus
typi. (Type, B. monticola.)

Sect. V. Greenmania Sherff, op. cit. 88 : 297. 1929. Nos. 63-73.

Herbae Americae tropicae perennes, plerumque scandentes,
caulibus saepe 5-10 m. longis; capitulis numerosis, normaliter radia-
tis; achaeniis elongatis, valde obcompressis vel omnino planis,
lateribus parallelis et saepissime valde setosis, apice plerumque
biaristatis aristis saepius longis nunc retrorsum hamosis nunc calvis.
(Type, B. Rubifolia.)

Sect. VI. Selvorngea Sherff, op. cit. 93: 214. 1932. No. 74. 3
Herbae perennes, glabrae; foliis sessilibus, decussatis, rigidis,

oblanceolato-oblongis, serratis, etc. Cum characteribus typi.

(Type, B. graveolens.)

Sect. VII. Fulsotsia Sherff, loc. cit. No. 75. 4
Caulis glaber fere nudus, foliis 3-4-jugis, parvis, sessilibus, in-
tegris, linearibus. Cum characteribus typi. (Type, B. fistulosa.)

Sect. VIII. Heterodonta (Nutt.) Sherff, loc. cit. Pro sect.?
Diodontae Nutt. Trans. Amer. Phil. Soc. ser. II. 7: 361. 1841. Sect.

1 Named for Mr. Otto Degener, the well-known authority on the flora of the
Hawaiian Islands.

2 Name anagrammatic for monticola.

3 Name anagrammatic for graveolens.

4 Name anagrammatic for fistulosa.

32 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

Hederodonta Nutt. ex Walp. (generis Diatontae Nutt. ex Walp.)
Repert. 2: 615. 1843. Nos. 76 and 77.

Plantae boreali-americanae, foliis plerumque simplicibus, capi-
tulis discoideis vel subradiatis et cylindricis vel ellipsoidalibus,
achaeniis planis lineari-cuneatis. (Type, B. Bidentoides.}

Sect. IX. Meduseae (Nutt.) Sherff, loc. cit. Pro sect. Diodontae
Nutt. Trans. Amer. Phil. Soc. ser. II. 7: 360. 1841. Diodonta Nutt.
(sed syn. Coreopsis aurea Ait. et Diodonta Bidentoides Nutt. exclu-
denda sunt) loc. cit. Pro sect. Diatontae Nutt. ex Walp. Repert.
2: 615. 1843. Diatonta Nutt. ex Walp. (exclud. syn. Coreopsidem
auream Ait.), op. cit. 614. Diadonta Nutt. ex Walp. op. cit. 6: 164.
1846. Pro subsect. sectionis Eucoreopsidis Pfeiffer, Nom. Bot. 1:
1085. 1874 (non vere Torr. & Gray). Nos. 78-82.

Plantae boreali-americanae; foliis plerumque pinnatis raro in-
divisis vel bipinnatis; capitulis radiatis luteis; achaeniis planis nunc
lineari-cuneatis nunc cuneato-obovatis saepe crasso-marginatis et
plus minusve tuberculatis, exaristatis vel biaristatis aristis saepius
antrorsum hamosis. (Type, B. polylepis.)

Sect. X. Platycarpaea DC. Prodr. 5: 594. 1836. Nos. 83-94.

Folia plerumque simplicia vel pinnatim 3-7-partita (raro 2-3-
pinnatisecta) ; achaeniis ovalibus vel obovato-cuneiformibus, obcom-
presso-planis vel apicem versus tetragonis. (Type, or at least first
cited species, B. tripartita.)

Sect. XL Psilocarpaea DC. Prodr. 5: 596. 1836. Nos. 95-218.

Plantae habitu valde diversae, nunc annuae nunc perennes,
herbae vel frutices; foliis simplicibus vel (etiam valde) decompositis;
capitulis discoideis vel radiatis, nunc minimis nunc maximis; achae-
niis plerumque plus minusve linearibus, planis vel tetragonis, apice
muticis vel aristatis. A large section, containing more than half of
the species in the genus. Future studies may indicate the advisability
of splitting this section into several smaller groups. (Type species
not indicated by DeCandolle. B. fruticosa (Vest) DC., cited first by
DeCandolle, unknown both to him and to me. B. decolor ata H.B.K.,
the next species cited, reduces to B. aurea, which species may there-
fore serve as the section type.)

Sect. XII. Steppia (Schz. Bip. in Walp.) Sherff, op. cit. 215.
Pro sect. Coreopsidis, Schz. Bip. in Walp. Repert. 6: 163. 1846.
Nos. 219-231.

THE GENUS BIDENS 33

Folia dentibus apicaliter setigeris saepius dentata; floribus tubu-
losis ad medium saepius tumido-articulatis vel anulatis; achaeniis
plerumque biaristatis aristis antrorsum hispidis. (Type, B. chaeto-
donta.)

Sect. XIII. Lesperthema Sherff, op. cit. 216. No. 232. 1
Involucri bracteae interiores basaliter vel etiam usque ad medium

connatae. Achaenia exteriora marginibus perspicue incrassata.

(Type, B. phelloptera,)

Sect. XIV. Ebussa Sherff, loc. cit. No. 233. 2

Involucri bracteae interiores basaliter vel etiam usque ad medium
connatae. Achaenia praecocia, clavato-linearia, exalata, apice plus
minusve incrassato-capitata vel crassiusculo-anulata. (Type, B.
praecox.)

CLAVIS

a. Plantae insulis Oceani Pacifici centralis nativae.*

6. Folia plerumque indivisa.
c. Inflorescentia monocephalica pedunculataque.

d. Folia tomentoso-pubescentia 11. B. Lantanoides.

d. Folia glabra.

e. Petioli laminas aequantes superantesve.
/. Achaenia alata.

56. B. mauiensis var. cuneatoides et var. Forbesiana.

f. Achaenia exalata 57. B. molokaiensis.

e. Petioli laminis breviores.
/. Folia basi late cuneata, utroque latere 3-5 dentibus

grosse dentata.

g. Folia membranacea, saepius 2-3 cm. lata, dentibus in
unico latere saepe usque ad 12; achaeniis costis
marginibusque dense setosis apice biaristatis.

59. B. Saint- Johniana.

1 Name anagrammatic for that of Thelesperma, which genus is strongly sug-
gested by the interior bracts, these being connate below (as are also those in Sect.

XIV).

2 Name anagrammatic in honor of Dr. Walter Busse, collector of the type, the
name Bussea having already been used (pro genere) by Harms (Bot. Jahrb. 33:
159. 1902) in another connection.

3 Introduced species, being readily distinguishable from the indigenous ones,
are here omitted. The introduced species commonly found in certain localities,
especially in the Hawaiian Islands, are: Bidens laevis, B. pilosa, B. biternata, B.
Cynapiifolia, andS. tripartita (the last apparently absent in the Hawaiian group).
The central Pacific region, as here taken, extends from the Tropic of Cancer
southward to slightly past the Tropic of Capricorn (Maretiri or Bass Isls.) and
from about 127 to 180 W. Long.

34 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

g. Folia crassiuscula, 1-2 cm. lata, dentibus in unico
latere plerumque 3-5; achaeniis marginibus sparsis-

sime ciliatis apice exaristatis 58. B. cuneata.

f. Folia basi rotundata vel cordata, utroque latere 6-15

dentibus serrata 57. B. molokaiensis.

c. Inflorescentia capitulorum paucorum multorumve, cymosa vel

paniculato-corymbosa.
d. Capitula ad anthesin minuta, tantum 2-4 mm. alta.

e. Achaenia 6-8 mm. longa; speciebus insularum sandvicen-

sium 22. B. Degeneri.

e. Achaenia plerumque 2.5-6 mm. longa; speciebus hemi-

sphaerii australis.

/. Folia plus minusve oblongo-ovata, breviter acuminata,

petiolis crassiusculis 1.2-1.4 mm. latis. .1. B. Ahnnei.

/. Folia lanceolata vel oblongo-lanceolata vel lanceolato-

ovata, caudato-acuminata, petiolis tenuibus 0.6-0.8

mm. latis.

g. Achaenia plerumque lineari-fusiformia, corpore 2-3
mm. longa et 0.7 rarius usque ad 1 mm. lata, calva
vel brevissime 1- vel 2-aristata aristis adrecte his-
pidulis et usque ad 0.3 mm. longis; planta ex insulis

Marquesas 2. B. polycephala.

g. Achaenia lineari-oblonga, corpore 3.5-5 mm. longa et
1.25 mm. lata, biaristata aristis retrorsum hamosis
0.5-1 mm. longis; planta ex insula Raiatea.

3. B. deltoidea.
f. Folia angustiora, plerumque anguste lanceolata vel

oblongo-lanceolata 13. B. australis.

d. Capitula ad anthesin majora.

e. Folia plerumque anguste lanceolata vel anguste oblongo-
lanceolata.
/. Plantae marquesianae.

g. Achaeniorum corpora circ. 4 mm. longa.

4. B. Jardinii.
g. Achaeniorum corpora circ. 6 mm. longa.

5. B. Bipontina.

f. Plantae nee marquesianae nee sandvicenses.
g. Capitula pauca (8 in unico ramo).

THE GENUS BIDENS 35

h. Folia tenuiter petiolata; involucri bracteis exteri-
oribus 3-6 mm. longis, patentibus reflexisve;
achaeniis dense erecto-hispidis . .15. B. Mathewsii.

h. Folia alato-petiolata; involucri bracteis exterioribus
8-12 mm. longis, adpressis; achaeniis porriginosis.

19. B. orofenensis.
g. Capitula numerosiora.

h. Folia unico latere 20-40 (raro -75) -dentata; capi-
tulis 6-7.5 mm. latis et 3-4 mm. altis; involucri
bracteis exterioribus circ. 1 mm. longis interioribus
circ. 2 mm. longis; floribus ligulatis 2-3 mm. longis.

13. B. anstmlis.

h. Folia unico latere 6-17-dentata; capitulis 15 mm.
latis et 6 mm. altis; involucri bracteis exterioribus
circ. 3 mm. longis interioribus circ. 3.5 mm.
longis; floribus ligulatis circ. 8 mm. longis.

12. B. mooreensis.

/. Plantae sandvicenses; achaeniorum corporibus 8-11.5
mm. longis.

g. Involucri bracteae exteriores 1-2 mm. longae; capitulis
numerosis; multis foliis divisis; floribus ligulatis
plerumque 3-5.

h. Capitula distantia, planta lanaiensi. 21. B. distans.
h. Capitula congesta, planta molokaiensi.

52. B. micrantha var. caduca.

g. Involucri bracteae exteriores 2-5 mm. longae; capitulis
vix numerosis; foliis plerumque indivisis; floribus
ligulatis 7-8.
h. Achaeniorum aristae sub corporis apice positae.

20. B. hawaiensis.
h. Achaeniorum aristae ex apice ipso ortae.

35. B. Skottsbergii var. conglutinata.
e. Folia latiora.
/. Folia subtus pubescentia.

g. Folia utrinque pubescentia 7. B. Beckiana.

g. Folia supra sparsim pubescentia vel demum sub-

glabrata 8. B. cordifolia.

/. Folia plus minusve glabra (hie stant etiam f ormae depressae
sarmentosae humiles simplicifoliae Bidentis graciloidis).

36 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

g. Caules ramive plus minusve glauci; plantis sandvicen-

sibus.
h. Involucri bracteae exteriores 1-2.5 mm. longae.

i. Folia simplicia ovata vel rhomboideo-ovata.

26. B. ctenophylla.

i. Folia simplicia oblongo-lanceolata.
;. Achaeniorum aristae sub corporis apice positae.

20. B. hawaiensis.
j. Achaeniorum aristae ex apice ipso ortae.

35. B. Skottsbergii var. conglutinata.
h. Involucri bracteae exteriores circ. 4-5 mm. longae.

23. B. asymmetrica.
g. Caules ramive interdum pallidi (B. Populifolia) sed

non glauci.

h. Folia plus minusve ovato-lanceolata vel ovata,

basaliter cuneata vel rotundata raro vix subcor-

data, petiolis 0.5-3 cm. longis; plantis non sand-

vicensibus.

i. Capitula ad anthesin 3.3-4 cm. lata; foliis acriter

serrata 17. B. Henryi.

i. Capitula angustiora.
j. Folia leviter vel obsolete serrulata vel subin-

tegra.
k. Achaenia alata, 2.3-3 mm. lata.

9. B. hivoana.
k. Achaenia exalata, circ. 1 mm. lata.

10. B. hendersonensis et var. oenoensis.
j. Folia acriter serrata.

k. Folia crassiuscula; planta e Tahiti.

18. B. glabrata.
k. Folia membranacea.
I. Achaenia exalata.

w. Achaenia corpore 5-10 mm. longa.
n. Achaenia exaristata, corpore 9-10
mm. longa; involucri bracteis exteri-
oribus perspicue spathulatis quam
interioribus longioribus; planta ex
insula Raiatea. . . .14. B. raiateensis.

THE GENUS BIDENS 37

n. Achaenia biaristata, corpore 5-8 mm.
longa; involucri bracteis exterioribus
oblongo-linearibus quam interioribus
paulo brevioribus; planta ex insula

Pitcairn 15. B. Mathewsii.

m. Achaenia corpore 2.5-4.5 mm. longa.
n. Achaenia plerumque biaristata, cor-
pore 3.8-4.5 mm. longa; planta ex
insula Tahiti .... 16. B. aoraiensis.
n. Achaenia vix vel non aristata, corpore
circ. 2.5 mm. longa; planta ex insula

Hiva Oa 6. B. collina.

L Achaenia crassiusculo-marginata vel -alata,
marginibus apice in aristas productis.

27. B. glandulifera.
h. Folia si simplicia ovata, basi subcordata vel cordata ;

petiolis usque ad 6 vel etiam ad 10 cm. longis.
i. Planta ex insulis marquesianis; foliis subtus
secundum rachidis basim caespitose hispidis.

33. 5. uapensis.

i. Plantae ex insula Oahu; foliis glabris.
y. Folia obtuse dentata; achaeniis anguste lineari-
bus, exalatis, corpore 7-12 mm. longis.

34. B. Populifolia.

j. Folia acriter dentata; achaeniis late linearibus,
saepe alatis, corpore 1.2-2 cm. longis.

28. B. macrocarpa var. ovatifolia.

h. Folia si simplicia oblongo-ovata, basi late cuneata;

petiolis circ. 1-3 cm. longis; planta ex insula

Hawaii 35. B. Skottsbergii.

b. Folia plerumque divisa.

c. Capitula magna, ad anthesin 5 cm. lata; stylis 6-10 mm.
antheras superantibus, ramis abrupte longo-caudatis.

60. B. Cosmoides.
c. Capitula minora, plerumque solis stylorum ramis supra antheras

projectis.

d. Folia bipinnatim divisa, segmentis ultimis angustis (vel in
B. waianensi interdum lata).

e. Plantae decumbentes vel adscendentes.

38 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

/. Capitula solitaria vel longe pedunculata.

56. B. mauiensis var. lanaiensis.
f. Capitula corymbosa vel paniculata.

55. B. Hillebrandiana.
e. Plantae erectae.
/. Pedicellae pedunculique minimi dense et insigniter

albido-pubescentes 26. B. ctenophylla.

f. Pedicellae vel pedunculi glabri.

g. Achaenia spiraliter volubilia vel torta; foliorum
segmentis late linearibus vel latioribus.

54. B. waianensis.

g. Achaenia recta vel paululum torta, corpore 8-13 mm.
longa, foliorum segmentis linearibus vel filiformibus,
vel raro latioribus ac dentibus elongatis angustis
perspicue dentatis.

53. B. Menziesii et var. filiformis et var. leptodonta.

g. Achaenia recta vel subrecta, corpore 6-9 mm. longa;

foliorum principalium segmentis rhomboideo-ovatis

vel cuneate lineari-lanceolatis, dentibus non elongatis.

37. B. sandvicensis var. typica f. compositior.

g. Achaenia recta vel subrecta, corpore circ. 3-7.5 mm.

longa.

h. Achaenia corpore 6-7.5 mm. longa. 36. B. obtusiloba.
h. Achaenia corpore circ. 3 mm. longa.

32. B. pulchella.
d. Folia ternatim vel pinnatim divisa, vel interdum imperfecte

bipinnata.

e. Plantae decumbentes vel adscendentes.
/. Capitula solitaria vel longe pedunculata.

56. B. mauiensis etiam var. cuneatoides et var. media,
f. Capitula cymosa, corymbosa, vel paniculata.

g. Paleae usque ad 1 cm. longae, achaenia matura biaris-

tata superantes 55. B. Hillebrandiana.

g. Paleae multo breviores atque achaeniis plerumque

exaristatis multo superatae.
h. Capitula pansa ad anthesin 1.1-1.5 cm. lata.

25. B. graciloides.
h. Capitula pansa ad anthesin 6-8 mm. lata.

22. B. Degeneri var. Apioides et f . filicifolia.

THE GENUS BIDENS 39

e. Plantae erectae.

/. Achaeniorum aristae principales plerumque infra cor-
poris apicem ortae et corporis marginibus continuae,
vel deficientes.

g. Achaenia valde torta 54. B. waianensis.

g. Achaenia recta vel paulum curvata.

h. Achaenia angusta (0.5-1.7 mm. lata), atra, exalata
vel rarius subalata; capitulis ad anthesin 4-6
mm. alta et 1.5-2 cm. lata.

i. Capitula numerosa, saepe dense corymbosa vel
paniculata; achaeniis maturis plerumque ad
facies et margines glabris.

j. Ligulae apice saepe profundissime incisae;
achaeniis inferne plerumque 1-3-setosis, setis
elongatis erectis partim adnatis.

26. B. ctenophylla.

j. Ligulae non vel tantum moderate dentatae;
setis basalibus elongatis partim adnatis utro-
que margini achaeniorum deficientibus.

k. Achaenia matura perspicue ac intense nigra;
involucri bracteis exterioribus tantum circ.

1.5 mm. longis 52. B. micrantha et

var. kaalana et var. laciniata.

k. Achaenia matura atra vel parce nigra sed
non intense perspicueque nigra.

I. Involucri bracteae exteriores tantum 1-2
mm. longae.

m. Ligulae elliptico-oblongae, aegre denti-
culatae, 1.5-3 mm. latae; achaeniis
glabris.

n. Capitula distantia, planta lanaiensi.

21. B. distans.

n. Capitula congesta, planta molokaiensi.
52. B. micrantha var. caduca.

m. Ligulae cuneato-obovatae, dentatae vel

lobulatae, 3-5 mm. latae; achaeniis

basim versus lateraliter erecto-setosis.

40. B. fecunda.

40 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

I. Involucri bracteae exteriores plerumque

2.3-5 mm. longae.

m. Foliola non nisi inferiora petiolulata.

38. B. conjuncta.
m. Foliola normaliter tenui-petiohilata.

40. B. fecunda.

i. Capitula p'auciora, cymoso-corymbosa vel hac
atque iliac sparsa; achaeniis maturis atris ac
non nitidis, ad margines setosis.

51. B. waimeana.

h. Achaenia matura saepe latiora, subbrunnea vel

brunneo-nigra, saepe alata; capitulis ad anthesin

7-15 mm. altis et 2-3 cm. latis.

i. Capitula ad anthesin 7-8 mm. alta et circ. 3 cm.

lata; involucri bracteis subaequalibus circ. 6

mm. longis; floribus ligulatis 1-1.6 cm. longis;

floribus tubulosis 15-20. . . .28. B. macrocarpa.

i. Capitula ad anthesin 8-15 mm. alta et circ. 2 vel

vix 2.5 cm. lata; involucri bracteis exteriorfbus

minoribus plerumque 1.5-3 mm. longis; floribus

ligulatis 6-9 mm. longis; floribus tubulosis 30-45.

29. B. magnidisca.

/. Achaeniorum aristae deficientes vel principales plerum-
que ex apice ipso ortae.

g. Involucri immaturi bracteae exteriores reflexae; involu-
cro interiore perspicuo et ei Cosmidis bipinnati Cav.
simili 50. B. amplectens.

g. Involucri immaturi bracteae exteriores erectae vel

patentes.

h. Capitula plerumque solitaria, pedunculis usque ad
11 cm. longis, bracteis exterioribus valde foliaceis.

48. B. valida.

h. Capitula ac bracteae exteriores diversae.
i. Achaenia spiraliter volubilia vel valde torta.
j. Achaenia plerumque per 3-5 revolutiones voluta.

44. B. torta.

j. Achaenia plerumque per 0.6-2 revolutiones
voluta.

k. Folia caulina 3-5-partita.

THE GENUS BIDENS 41

1. Capitula numerosa, parva, ad anthesin
3.5-6 mm. alta et circ. 0.9-1.5 (rarius -2)
cm. lata.

m. Foliola saepius ovato-lanceolata vel late
oblongo-lanceolata, apice saepius sub-
obtusa vel tantum breviter acuminata.

n. Foliola juvenia plerumque pilis
numerosis fulvescentibus vel etiam
ferrugineis obsita; achaeniis 0.6-0.8
mm. latis, exaristatis.

45. B. fulvescens.

n. Foliola primo glaberrima; achaeniis
1-1.7 mm. latis, biaristata aristis
tenuibus db 1 mm. longis.

23. B. asymmetrica.

m. Foliola lanceolata breviter vel longe
acuminata, primo viridia.

n. Folia (petiolis inclusis) principalia
5-13 cm. longa 39. B. Wiebkei.

n. Folia (petiolis inclusis) principalia
1-2.5 dm. longa 43. B. Forbesii.

1. Capitula pauca, ad anthesin majora, 6-12
mm. alta et 2 cm. latajfoliisprincipali-
bus (petiolis inclusis) 1-2.5 dm. longis.

w. Achaenia apice calva vel irregulariter
1-2-aristata aristis usque ad circ. 1.3
mm. longis 46. B. Campylotheca.

m. Achaenia biaristata aristis longis (4
mm.), filiformibus, deciduis.

47. B. nematocera.

k. Folia caulina plerumque 5-7-partita.

1. Foliorum caulinorum foliola inferiora saepe
alternata; achaeniis anguste linearibus,
apicem versus anguste elongatis.

24. B. cervicata.

L Foliorum caulinorum foliola inferiora ple-
rumque opposita; achaeniis superne tan-
tum paulum angustatis.

42 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

m. Internodia longa; foliis paucis et mag-
nis; capitulis paucis, pansis ad anthesin
3-4 cm. latis.

46. B. Campylotheca var. pentamera.

w. Internodia brevia; foliis plerumque sub-
numerosis, magnitudinis mediae; capi-
tulis plerumque numerosissimis, unico
specimine in herbario 50-200 ferente,
his pansis ad anthesin tantum circ.
1.5-2 cm. latis 54. B. waianensis.

i. Achaenia recta, curvata, vel tantum paulum torta.

j. Inflorescentiae rami late patentes, 1-pauci-capi-
tulati; internodiis caulis ac ramorum ple-
rumque longis.

46. B. Campylotheca et var. pentamera.

j. Habitus diversus.

k. Folia principalia plerumque 3-partita.

I. Foliola anguste lanceolata, crenato-serrata,
terminali apice longo-attenuato ; capitulis
non numerosis 31. B. Asplenioides.

1. Foliola lanceolata vel ovata (et non elonga-
tiora nisi cum capitulis numerosis),
acute serrata, terminale apicaliter acutum
vel acuminatum sed non longo-attenua-
tum.

m. Capitula ad anthesin minuta, 6-8 mm.
lata et 4-5 mm. alta.

22. B. Degeneri var. Apioides.

m. Capitula ad anthesin majora.

n. Caulis (basi excepta) et rami acute
tetragoni, superne herbacei.

o. Foliola lateralia plerumque sessilia;
achaenii corpore 10-16.5 mm.
longo.

p. Involucri bracteae exteriores 1.5-
2 (raro -2.5) mm. longae; achae-
niiscirc. 0.7-0.8 mm. latis, exaris-
tatis 45. B. fulvescens.

THE GENUS BIDENS 43

p. Involucri bracteae exteriores 2-7
(plerumque 4-6) mm. longae;
achaeniis circ. 1 mm. latis,
plerumque aristatis.

38. B. conjuncta.

o. Foliola petiolulata ; capitulis numero-
sissimis; achaenii corpore 10-12.5

mm. longo 40. B. fecunda.

o. Foliorum majorum principalium foli-

ola lateralia petiolulata; achaenii

corpore 6-10 mm. longo.

p. Capitula demum in herbarii speci-

minibus siccis dense adgregata

ac plerumque inter se tangentia,

aequaliter vel subaequaliter

edita 41. B. coartata.

p. Capitula demum in herbarii speci-

minibus siccis sparsa, rariter

inter se tangentia, nee in eodem

nee fere eodem aequo stantia.

37. B. sandvicensis.

n. Caulis et rami rotundato-tetragoni,

superne vix herbacei.
o. Achaenia matura plus minusvetorta.
p. Achaeniorum aristae deficientes
vel usque ad 1 mm. longae.

23. B. asymmetrica.
p. Achaeniorum aristae elongatae et
inaequaliter flexuosae usque ad
4 mm. longae.

47. B. nematocera.
o. Achaenia matura recta vel curvata,

non torta.

p. Involucri bracteae exteriores ple-
rumque fere vel interdum plene
interioribus aequales.

51. B. waimeana.

p. Involucri bracteae exteriores
quam interiores tertio vel dimi-
dio breviores. 25. B. graciloides.

44 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

k. Folia principalia saepius 5-partita.

/. Capitula 2-5-adgregata, ramis tenuibus
longis erectis nudis gesta, separatim
pedimculata pedunculis plurime 2-5.5
cm. longis; ad anthesin 7-8 mm. alta.

49. B. Stokesii.

L Capitula cymoso-corymbosa vel paniculata,

pedunculis vel pedicellis plurime breviori-

bus; ad anthesin plerumque 4.5-7 mm.

alta.

m. Achaenia plerumque glabra, vel superne

sparsim setosa.

n. Foliola anguste lanceolata, crenato-
serrata, terminale apicaliter longo-
attenuatum; herba ex insula Niihau
(insularum Sandvicensium).

31. B. Asplenioides.
n. Foliola moderate vel late linearia.
o. Pedicellae pedunculique glabri.

42. B. Salicoides.

o. Pedicellae pedunculique albido-

pubescentes. . . .26. B. ctenophylla.

n. Foliola lanceolata vel ovata, acute

serrata, terminale apicaliter acutum

acuminatumve sed non longo-attenu-

atum 37. B. sandvicensis.

m. Achaenia marginibus moderate vel copi-

ose setosa.

n. Plantae plerumque 2-5 dm. altae.
o. Inflorescentia manifeste supra folia

exserta 30. B. micranthoides.

o. Inflorescentia (totius plantae et non

solius rami) non manifeste supra

folia exserta .... 25. B. graciloides.

n. Plantae plerumque 4-9 dm. altae.

o. Capitula pansa ad anthesin 2.6-3.1

cm. lata; achaeniis perspicue aris-

tatis (aristis circ. 4 mm. longis).

47. B. nematocera.

THE GENUS BIDENS 45

o. Capitula pansa ad anthesin usque
ad 1.5 cm.lata;achaeniorum aristis
deficientibus vel usque ad circ.
1 mm. longis.

p. Habitu B. asymmetricae adpro-
pinquans; foliis pinnatis, foliolis
ovato-lanceolatis, foliolo termi-
nal! folii majoris omnino circ.
6-16-dentato . . 51. B. waimeana.

p. Habitu B. sandvicensi adpropin-
quans.

q. Folia pinnata, foliolis ovatis vel
lanceolatis vel saepius ovato-
lanceolatis, foliolo terminali
folii majoris omnino circ. 22-
26-dentato.
37. B. sandvicensis var. setosa.

q. Foliola inferiora saepius rursus
partita, alia plerumque line-
aria, foliolo terminali folii
majoris omnino circ. 2-8-
dentato ... 37. B. sandvicensis
var. imminuta.

a. Plantae in America boreali centralique etiam
in insulis Occidentali-Indicis crescentes.

b. Herbae vel frutices perennes, scandentes, achaeniis linearibus

biaristatis plus minusve planis longe ciliatis.
c. Folia totius plantae plerumque indivisa.

d. Achaenia corpore 8-13 mm. longa . . 71. B. segetum var. patula.

d. Achaenia corpore 1-2.2 cm. longa 72. B. Shrevei.

c. Folia plerumque divisa.

d. Involucri bracteae exteriores 9-15 mm. longae.

e. Folia tripartita 73. B. Holwayi.

e. Folia bipinnata vel tripinnatisecta 69. B. Gentryi.

d. Involucri bracteae exteriores 3-8 mm. longae.
e. Folia principalia pinnatim 3-7-partita.
/. Foliolum terminale anguste lanceolatum; caule pilis
densis pubescenti ; planta jamaicensi .... 64. B. incisa.

46 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

/. Foliolum terminale latius; caule glabro vel tomentoso.
g. Planta antillana, rarissime alibi crescens . .63. B.reptans.

g. Planta Americae septentrionalis australisque, rarissime
antillana. .65. B. squarrosa (et raro 71. B. segetum}.

e. Folia principalia 2-3-pinnata.

63. B. reptans var. Urbanii et var. dissecta.

6. Non scandentes (sed apud B. clarendonensem longe repentes).

c. Capitula perspicue radiata floribus ligulatis maxima ex parte
flavis vel aurantiacis.

d. Achaenia aristata aristis retrorsum hamosis (raro caducis).

e. Flores ligulati rubido-aurantiaci ; achaeniis validis, acute
quadrangulatis, plus minusve recurvatis, plerumque
4-aristatis 138. B. Sambucifolia.

e. Flores ligulati flavi.
/. Achaenia omnia valde cuneata, non alato-marginata.

g. Capitula hemisphaerica, ad anthesin plerumque cer-
nua; involucri bracteis exterioribus reflexis vel vix
adscendentibus; achaeniis transversim rhomboideis,
faciebus graciliter atque obscure striatis, saepe
tuberculatis.

h. Achaenia arcuata, valde carinata, cortice pallido
marginata; paleis apice plerumque flavidis; ligulis
usque ad circ. 1.7 cm. longis vel deficientibus;
capitulis demum saepius cernuis.

92. B. cernua et var. oligodonta.

h. Achaenia recta, plana, non cortice-marginata; paleis
apice rubidis; ligulis 1.5-3 cm. longis; capitulis
raro cernuis 93. B. laevis.

g. Capitula campanulata vel subhemisphaerica, ad anthe-
sin erecta; involucri bracteis erectis adscendentibus;
achaeniis biconvexis, grosse perspicueque striatis,
non tuberculatis. . . .94. B. hyperborea et varietates.

/. Achaenia exteriora obovata vel cuneato-obovata, mar-
gine plerumque interrupte crassiusculo-alata.

g. Involucri bracteae exteriores 8-10, saepius laeves vel
leviter ciliatae, 0.5-1.2 cm. longae.

78. B. aristosa var. Fritcheyi.

THE GENUS BIDENS 47

g. Involucri bracteae exteriores plerumque 15-20, per-
spicue hispido-ciliatae, 1-2.7 cm. longae.

79. B. polylepis var. retrorsa.

f. Achaenia omnia magis elongata, plerumque cuneato-
linearia vel anguste linearia.

g. Ligulae plerumque bicolores, basi purpureae alibi
flavae 158. B. bicolor.

g. Ligulae unius colons.

h. Folia simplicia (raro formae simplicifoliae B. aureae

stant hie).

i. Folia oblongo-ovata vel oblongo-lanceolata, mar-
gine integra vel raro 1-dentata; caule erecto.

101. B. integrifolia.

i. Folia ovato-lanceolata, serrata, petiolo adjecto
plerumque 1.5-4 cm. longa; caulibus procum-
bentibus vel adscendentibus, 1-7 dm. longis;
planta numquam in india occidental! crescente.

150. B. triplinervia.

i. Folia rhomboideo-ovata, grosse serrata 5-16
dentibus in unico latere, petiolo adjecto 5-10
cm. longa; caulibus repentibus, usque ad 4 m.
longis; planta jamaicensi. 61. B. clarendonensis.

i. Folia linearia; caule erecto.

146. B. angustissima var. Linifolia.
h. Folia divisa.

i. Herbae annuae vel biennes.

j. Planta demissa, saepe ramosissima, plerumque
1-2.5 dm. alta, foliis petiolo adjecto 1-5
(rarius -7.5) cm. longis . 147. B. Anthemoides.

j. Planta erecta, moderate ramosa, plerumque
altior, foliis saepius 0.5-2 dm. longis.

k. Achaenia interiora corpore 10-16 mm. longa.

154. B. serrulata.

k. Achaenia omnia corpore 4-7 mm. longa.

I. Folia principalia plerumque indivisa vel
3-5-partita, rarissime bipinnata.

m. Planta 3 dm. alta; foliis petiolo ad-
jecto 1.5-1.8 cm. longis; capitulis ad

48 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

anthesin circ. 1.5-1.8 cm. latis; floribus
ligulatis plerumque 8.

98. B. Coreocarpoides.

m. Planta plerumque 5-10 dm. alta; foliis
petiolo adjecto 0.8-2.2 dm. longis;
capitulis ad anthesin 2-5 cm. latis;
floribus ligulatis plerumque 5 vel 6.

100. B. aurea.

L Folia principalia bi- vel subtripinnata.

97. B. Ferulae/olio, et varietates.

i. Herbae perennes.
j. Involucri bracteae exteriores 10-20.

k. Folia principalia tripartita foliolis plus mi-
nusve ovatis 156. B. chiapensis.

k. Folia principalia bipinnatisecta segmentis
plus minusve linearibus.

155. B. Geraniifolia.

j. Involucri bracteae exteriores 5-10.
k. Flores ligulati fertiles.

L Folia tripartita, foliolis ovatis vel rhomboi-
deo-ovatis 157. B. Ostruthioides.

I. Folia bipinnatisecta vel biternatisecta folio-
lis segmentisve cuneato-lanceolatis.
157. B. Ostruthioides var. costaricensis.

L Folia bipinnatim dissecta segmentis longis

filiformibus 141. B. nudata.

k. Flores ligulati steriles.

I. Foliola angustissime linearia, plerumque
0.3-0.6 mm. lata. .146. B. angustissima.

L Foliola latiora.
m. Flores ligulati 5 vel 6.

n. Foliorum segmenta primaria subfla-
belliformia 152. B. insolita.

n. Foliorum segmenta primaria non sub-

flabelliformia . 150. B. triplinerviavar.

macrantha et var. mollis.

m. Flores ligulati 7-10.

THE GENUS BIDENS 49

w. Involucri bracteae exteriores 9-12
mm. longae 69. B. Gentryi.

n. Involucri bracteae exteriores 3-7 mm.
longae . . . 153. B. canescens (ac 147a.
B. Muelleri et rarissima 150. B. tripli-
nervia var. macrantha f. octoradiata).

d. Achaenia exaristata vel aristata aristis calvis vel antrorsum

setosis.
e. Achaenia exteriora late cuneata vel cuneato-obovata.

/. Achaenia nigra corpore 2.5-4.5 mm. longa; involucri
bracteis exterioribus 7-10 81. B. mitis.

f. Achaenia brunnea vel subnigra, corpore 5-7.5 mm. longa.

g. Involucri bracteae exteriores 8-10, glabrae vel mode-
rate ciliatae, quam interiores breviores.

78. B. aristosa et var. mutica.

g. Involucri bracteae exteriores 12-20, valde ciliatae vel
grosse hispidae, quam interiores plerumque longiores.

79. B. polylepis.
e. Achaenia exteriora anguste cuneata vel linearia.

/. Folia indivisa, nitido-subcoriacea, rhomboideo-ovata;
caulibus repentibus, usque ad 4 m. longis.

61. B. clarendonensis.
f. Folia divisa.

0. Planta demissa, saepe ramosissima, plerumque 1-2.5
dm. alta 147. B. Anthemoides.

g. Plantae erectae, moderate ramosae, altiores.

h. Achaeniorum corpus et aristae similes soliditate;
aristae transversim triangulatae.

80. B. coronata et var. tenuiloba*

h. Achaeniorum corpus et aristae soliditate dissimiles;
aristae transversim teretes.

i. Involucri bracteae exteriores apicem versus plus
minusve dilatatae, 1-2 mm. longae.

82. B. Oerstediana.

i. Involucri bracteae exteriores usque ad apicem
lineares, 3-7 mm. longae.

j. Involucri bracteae exteriores circ. 12, plerumque
5-7 mm. longae 151. 5. acrifolia.

50 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

y. Involucri bracteae exteriores 6-8, plerumque
3-5 mm. longae 96. B. Schaffneri.

c. Capitula discoidea vel subradiata vel perspicue radiata ligulis

albis vel rosaceis vel rubris sed non vere flavis.
d. Achaenia late vel anguste cuneata, sub apice non angustata. 1

e. Achaeniorum corpus striatum; foliis simplicibus vel pro-

funde incisis vel (apud B. tripartitam) 3-5-partitis.
/. Achaenia marginibus antrorsum hamosa, saltern basi ipsa.
g. Capitula terminalia 8-30-flora.

h. Achaenia fere linearia, transversim plano-convexa,
copiose pubescentia, sine costis medianis; aristis
angustissimis, patentibus, vix dimidio quam cor-

pore brevioribus 76. B. Bidentoides.

h. Achaenia plana vel biconvexa, sparsim pubescentia,
costis medianis perspicuis; aristis crassioribus,
longitudine non plus tertia parte corporis.
i. Capitula terminalia saltern 8 mm. longa.

77. B. Eatonii et varietates.
i. Capitula terminalia 4-7 mm. longa.

X B. multiceps (p. 208).
g. Capitula terminalia 30-60-flora.

h. Achaenia saltern matura ad apicem tetragona.

87. B. connata et varietates.

h. Achaenia plana 88. B. heterodoxa.

/. Achaenia marginibus retrorsum hamosa pro tota longi-
tudine.
g. Achaenia apice convexa ac cartilaginea.

h. Capitula hemisphaerica, ad anthesin plerumque
cernua; involucri bracteis exterioribus reflexis,
patentibus vel parce adscendentibus ; achaeniis
transversim rhomboideis, graciliter obscureque
striatis, saepe tuberculatis.

i. Achaenia recta planaque, non valde carinata,
sine marginibus corticis pallidae; paleis ad api-
cem rubidis; floribus ligulatis 1.5-3 cm. longis.

93. B. laevis.

1 For purposes of comparison, the steps under this d have been made to
correspond rather closely with those in Fassett's "A key to the northeastern
American species of Bidens" (Rhodora 27: 184-185. 1925).

THE GENUS BIDENS 51

i. Achaenia arcuata, valde carinata, cortice pallida
marginata; paleis ad apicem flavidis; floribus
ligulatis usque ad 1.7 cm. longis.

92. B. cernua et var. oligodonta.

h. Capitula campanulata vel subhemisphaerica, ad
anthesin erecta; achaeniis biconvexis, grosse ac
profunde striatis, non tuberculatis.

94. B. hyperborea et varietates.

g. Achaenia apice nee convexa nee cartilaginea.
h. Folia principalia 3-5-secta vel -partita.

i. Flores ligulati 8-11, circ. 3.5-8 mm. longi ; foliorum
lamina segmentisve profunde atque acerrime
incisis vel inciso-dentatis . . .91. B. amplissima.

i. Capitula normaliter discoidea (rarissime sub-
radiata) ; foliis normaliter 3-5-partitis, segmentis
serratis dentatisve sed non plerumque incisis.

89. B. tripartite,.

h. Folia simplicia 86. B. comosa.

e. Achaeniorum corpus non striatum; foliis saltern 1-2-
pinnatis, foliolo terminali plerumque petiolulato.

/. Involucri bracteae exteriores 3-5 (plerumque 4), non
evidenter ciliatae 83. B. discoidea.

f. Involucri bracteae exteriores 5-16, regulariter copioseque
ciliatae.

g. Involucri bracteae exteriores 10-16; interiores quam
discus breviores; achaeniis brunneis vel olivaceis.

85. B. vulgata et varietates.

g. Involucri bracteae exteriores 5-8; interiores disco
aequales; achaeniis subnigris.

84. B. frondosa et varietates.

d. Achaenia linearia vel clavata sed numquam manifeste
cuneata, supra saepe attenuata.

e. Involucri bracteae exteriores 3 vel 4, pro capitulo longis-
simae (1-2.5 cm.), nonnullae valde foliaceae atque irregu-
lariter 1-2-pinnatim partitae 124. B. Lemmonii.

e. Involucri bracteae exteriores simplices.

/. Achaeniorum aristae 3-5, regulariter una duaeve erectae
reliquae reflexae 137. B. riparia.

52 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

/. Achaenia exaristata vel aristata aristis inter se non
regulariter diverse spectantibus.

g. Foliorum segmenta plerumque linearia vel capilli-
formia.

h. Herba perennis; floribus ligulatis 8-10, apice trun-
cate grosse dentatis, 1.3-1.6 cm. longis.

145. B. Pringlei.
h. Herbae annuae.

i. Flores tubulosi pauci, plerumque 5-13.

;. Foliorum medianorum ac superiorum segmenta
lineari-filiformia 0.5-1 mm. lata.

121. B. heterosperma.

j. Foliorum medianorum ac superiorum segmenta
multo latiora 114. B. leptocephala.

i. Flores tubulosi multo numerosiores.
y. Capitulorum juvenilium discus saltern dimidio
bracteis exterioribus brevior; foliorum seg-
mentis linearissimis 0.5-1 mm. latis.

125. B. capillifolia.

y. Capitulorum juvenilium discus bracteis exteri-
oribus fere vel plene aequalis.

k. Involucri bracteae exteriores sub apice ple-
rumque dilatatae;ligulisalbidis vel rosaceis.
132. B. pilosa var. bimucronata f. odorata
et var. calcicola f. dissecta.

k. Involucri bracteae exteriores sub apice raro
dilatatae; ligulis flavis. .118. B. tenuisecta.

g. Foliorum segmenta anguste lanceolata vel latiora.
h. Achaenia omnia etiam primum exaristata.

i. Achaenia omnia valde clavata, glabra; ligulis
rosaceis 109. B. mollifolia.

i. Achaenia non clavata, supra antrorsum hispida;
ligulis albidis vel flavidis 111. B. Brandegeei.

h. Achaenia saltern interiora aristata.
i. Achaenia pauca, plerumque 5-14.

y. Achaenia matura plerumque plus minusve
recurvata, superne late distantia.

THE GENUS BIDENS 53

A;. Achaenia interiora corpore plerumque 12-21

mm. longa 107. B. Anthriscoides.

k. Achaenia interiora corpore plerumque 7-10

mm. longa 105. B. oligantha.

j. Achaenia matura recta vel subrecta, non

superne distantia.

k. Flores ligulati deficientes vel circ. 3, tantum
circ. 2.5 mm. longi . . . 114. B. leptocephala.

k. Flores ligulati circ. 5, plerumque 5-7 mm.
longi.

I. Folia pinnatim 3-5-partita.
ra. Achaenia exteriora badia rubrave.

104. B. amphicarpa.

m. Achaenia omnia atra . 103. B. oligocarpa.
I. Folia 2-3-pinnatisecta.

131. B. pseudalausensis.
i. Achaenia plerumque 16-50.
y. Flores ligulati pro capitulo perspicui, albi vel
rosacei.

k. Involucri bracteae exteriores 7-9.

I. Ligulae rosaceae ac caules adscendentes vel

plus minusve repentes, 1.5-4 dm. longi.

108. B. Chrysanthemifolia.

I. Nunc ligulae albidae vel rosaceae ac caules

erectae, nunc caules repentes subscanden-

tesve ac ligulae albae . . 132. B. pilosa var.

radiata, var. bimucronata, et var. calcicola.

k. Involucri bracteae exteriores 9-16.

112. B. aequisquama.
j. Flores ligulati minuti vel deficientes.

k. Achaeniorum maturorum aristae 5-7 mm.

longae ac divaricatae 117. B. cornuta.

k. Achaeniorum aristae usque ad 4 mm. longae
vel deficientes.

1. Achaenia plerumque recurvata; aristis 4-6.
136. B. Cynapiifolia et varietates.
I. Achaenia recta vel subrecta.

m. Folia simplicia vel simpliciter pinnata.

54 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

n. Achaenia valde dimorpha; nonnulla
exteriora clavata, badia vel rubro-
straminea, corpore tantum circ. 4.5-
5.5 mm. longa.

113. B. Bigelovii var. pueblensis.

n. Achaenia plus minusve similia.

o. Folia 5-partita foliolo terminal! circ.

2-3 cm. longo et 1-1.3 cm. lato;

achaeniis plerumque 2-aristatis.

134. B. domingensis.

o. Folia simplicia vel 3-partita, lamina
vel foliolo terminali 3.5-8 cm.
longa et 2-4 cm. lata; achaeniis
plerumque 3-4-aristatis.
128. B. tenera et var. paucidentata.

o. Folia rarissime simplicia plerumque
3-5-partita, lamina vel foliolo
terminali plerumque 2-10 cm.
longo, achaeniis 25-40, plerumque
2-3 (rarius 4-5) -aristatis.

132. B. pilosa et var. minor.

m. Folia foliolis saltern imis 2-3-pinnata.

w. Involucri bracteae exteriores 2-3 mm.
longae; achaeniorum interiorum cor-
pore 6-12 mm. longo; planta mexi-
cana 129. B. duranginensis.

n. Involucri bracteae exteriores 3-7.5

mm. longae.

o. Achaenia dimorpha, exteriora cla-
vata, rubido-badia vel rubido-
nigra, corpore tantum circ. 4-7
mm. longa, saepe setosiora; interi-
orum maturorum corporibus 8-12
mm. longis.

p. Folia tripartita interdum termi-
nalibus interdum omnibus seg-
mentis 3-5-partitis, lobis ob-
longis vel cuneatis; involucri
bracteis exterioribus 6-9; achae-

THE GENUS BIDENS 55

niorum interiorum aristis saepe

3, circ. 1.5-3 mm. longis. . .113.

B. Bigelomi et var. pueblensis.

p. Folia 1-2-pinnata, segmentis pri-
mariis lateralibus circ. 2 jugis,
superioribus simplicibus inferi-
oribus saepius tripartitis, seg-
mentis lanceolatis acriter
serratis; involucri bracteis ex-
terioribus 8-12; achaeniorum
interiorum aristis 2, circ. 1-1.5
mm. longis . . 99. B. Townsendii.

o. Achaenia inter se similia vel sub-
similia, corpore quam 12 mm.
saepe longiora; involucri bracteis
exterioribus 3-5 mm. longis.

p. Aristae erecto-patentes . . 115. B.
bipinnata et var. biternatoides.

p. Aristae erectae vel suberectae.
133. B. subalternans.

a. Plantae austro-americanae.

b. Flores ligulati plerumque brunneo-rubri vel purpurei, sicci saepe
plus minusve cinnamomei.

c. Capitula pansa ad anthesin circ. 2.5-3 cm. lata; achaeniis
valde tetragonis 3-4-aristatis aristis retrorsum et saepe oculis
pectinatim hamosis 139. B. Gardneri.

c. Capitula pansa ad anthesin circ. 4 cm. lata; achaeniorum sub-
tetragonorum aristis abortivis . . 143. B. Riedelii et var. hirsuta.

b. Flores ligulati diversi vel deficientes.

c. Herbae vel frutices perennes plerumque scandentes.
d. Folia indivisa.

e. Capitula pansa ad anthesin circ. 1.5-2 cm. lata; foliis 1-3
cm. latis 62. B. monticola.

e. Capitula pansa ad anthesin plerumque 3-5 cm. lata;
foliis 3-5.5 cm. latis.

/. Involucri bracteae exteriores numerosae (plerumque 12-
14), spathulato-obovatae, apice rotundae vel obtusis-
simae 67. B. simplicifolia.

56 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

/. Involucri bracteae exteriores 7-9, late lineares vel lineari-

spathulatae, apice acutae.

g. Achaenia corpora 8-13 mm. longa . . 71. B. segetum var.
patula (rarissime etiam 65. B. squarrosa}.

g. Achaenia corpore 1-2.2 cm. longa 72. B. Shrevei.

d. Folia 3-5-partita.

e. Omnia folia tantum 2-3.5 cm. longa. .68. B. Vincaefolia.
e. Folia longiora.

/. Folia plerumque subcoriacea ac rugosa . 66. B. Rubifolia.
f. Folia plus minusve membranacea.

g. Foliola valde perspicueque caudato-acuminata; achae-

niis marginibus glabris 70. B. urophylla.

g. Foliola moderate acuminata vel obtusiora; achaeniis

ciliatis.

h. Foliola plerumque anguste lanceolata raro ovato-
lanceolata; achaeniis corpore 8-13 mm. longis.

71. B. segetum.

h. Foliola vel ovata vel ovato-lanceolata vel lanceolata,
raro angustiora; achaeniis corpore 6-9 mm. longis.

65. B. squarrosa.

c. Herbae annuae perennesve, non scandentes.
d. Una vel duae aristae erectae reliquae perspicue reflexae.

137. B. riparia et var. refracta.
d. Aristae diversae vel deficientes.
e. Folia simplicia.
/. Capitula discoidea.
g. Folia glaberrima.

h. Folia principalia (inferiora exclusa) usque ad 3.5
cm. longa et 0.2-1 mm. lata ... 75. B. fistulosa.
h. Folia principalia 5-9 cm. longa et 2-3 cm. lata.

74. B. graveolens.

g. Folia tomentosa 142. B. brasiliensis.

/. Capitula radiata.

g. Achaenia anguste cuneata, plana vel 3-4-angulata
angulis retrorsum hamosis 93. B. laevis.

g. Achaenia elongata et plus minusve lineari-fusiformia,
corpore glabra vel antrorsum setosa.

THE GENUS BIDENS 57

h. Involucri bracteae exteriores apicem versus plus
minusve dilatatae.

132. B. pilosa var. radiata f. indivisa.
h. Involucri bracteae exteriores superne angustatae.
i. Flores ligulati plerumque 5 vel 6.

150. B. triplinervia.
i. Flores ligulati plerumque 8-10.
y. Planta 1-2 m. alta; involucri bracteis exteriori-

bus 8-14 mm. longis 144. B. Chodati.

j. Plantae caules plerumque 2-6 dm. longi; invo-
lucri bracteis exterioribus 5-6.5 cm. longis.

148. B. andicola.
e. Folia divisa.

/. Foliorum segmenta anguste linearia vel flagellaria (hac
stat raro etiam . . . 133. B. subalternans var. simulans).
g. Capitula discoidea vel vix subradiata.
h. Involucri bracteae exteriores 4-7, circ. 2-3 mm.
longae; achaeniis corpore 8-13 mm. longis.

122. B. exigua.

h. Involucri bracteae exteriores 7-10, circ. 3^4 mm.
longae; achaeniis corpore 1-1.4 cm. longis.

140. B. flagellaris.

h. Involucri bracteae exteriores 6-8, circ. 4-6 (rarius
8) mm. longae; achaeniis corpore 1-2.4 cm. longis.

130. B. pseudocosmos.
g. Capitula radiata.

h. Flores ligulati plerumque 4-6.
i. Flores ligulati tantum 3-4 mm. longi.

106. B. Andrei,
i. Flores ligulati saltern 1 cm. longi.

150. B. triplinervia.

h. Flores ligulati plerumque 8 . . 148. B. andicola var.
tarijensis f. dissecta (sed vide etiam 150. B. tripli-
nerviam var. macrantham f. octoradiatam) .
f. Foliorum lamina vel segmenta latiora.

g. Capitula perspicue radiata, floribus ligulatis mani-

feste flavis ac saltern 1 cm. longis.
h. Flores ligulati plerumque 5 vel 6.

150. B. triplinervia et varietates.

58 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

h. Flores ligulati plerumque 8.

148. B. andicola et varietates excl. var. Mandonii.

g. Capitula discoidea vel vix subradiata vel etiam
radiata sed cum floribus ligulatis albis rosaceisve non
vere flavis.

h. Involucri bracteae exteriores apicem versus dila-
tatae.

i. Achaenia interiora corpore 5-6 mm. longa, 2-3-

aristata aristis plerumque 1.5-2 mm. longis.

110. B. Abadiae et var. pilosoides.

i. Achaenia interiora corpore 6-16 mm. longa, 2-3
(-5) -aristata aristis 2-4 mm. longis.

132. B. pilosa et varietates.

h. Involucri bracteae exteriores apicem versus plerum-
que non dilatatae.

i. Achaenia recurvato-falcata.

136. B. Cynapiifolia et var. portoricensis.

i. Achaenia recta.

y. Folia principalia unipinnata 3-5 foliolis.
k. Achaenia plerumque 2-aristata.

I. Herba gracilis, infra simplex; capitulis in
fructu circ. 1.5 cm. altis et circ. 1 cm.
latis .... 148. B. andicola var. Mandonii.

I. Herba subrobusta, infra valde ramosa;
capitulis cum fructibus circ. 2-2.4 cm.
alta et superne circ. 1-1.8 cm. lata. .148.
B. andicola var. Cosmantha f. Buchtienii.

k. Achaenia plerumque 3-aristata.

128. B. tenera.
k. Achaenia plerumque 4-aristata.

/. Achaenia plerumque 6-15 (raro -20);
aristis saepius patentibus.

128. B. tenera var. paucidentata.

I. Achaenia numerosiora; aristis erectis.

133. B. subalternans var. unipinnata.

j. Folia principalia saltern 2-3-pinnata.

k. Achaenia exteriora (saltern demum) divari-
cata . 136. B. Cynapiifolia var. portoricensis.

THE GENUS BIDENS 59

k. Achaenia exteriora semper erecta vel sub-

erecta.

/. Aristae erectae vel suberectae.
TO. Foliola lateralia superiora circumam-
bitu ovata, apice obtusa vel subacuta.
135. B. Malmei.

TO. Foliola lateralia superiora circumam-
bitu lanceolata vel linearia, apice valde
acuta vel acuminata.
133. B. subalternans et var. simulans.

1. Aristae patentes 115. B. bipinnata.

a. Plantae hemisphaerii orientalis africanae exclusae.
b. Achaenia moderate vel late cuneata non linearia, sub apice non

angustata.

c. Achaenia faciebus striata.

d. Achaenia marginibus saltern basi ipsa 1-paucis setis antror-

sum munita .... 87. B. connata var. petiolata et var. fallax.

d. Achaenia marginibus totam longitudinem retrorsum hamosa.

e. Achaenia apice convexa cartilagineaque.

/. Folia simplicia; achaeniis quadrangulatis quadriaristatis

corpore 5-7.7 mm. longis 92. B. cernua.

/. Folia normaliter pinnatim 3-5-partita; achaeniis planis
biaristatis corpore 3-3.5 mm. longis ... 90. B. radiata.
e. Achaenia apice nee convexa nee cartilaginea.

89. B. tripartita et varietates.

c. Achaenia faciebus non striata; foliis pinnatim 3-5-partitis.
d. Involucri bracteae exteriores 5-8; interiores disco aequales.

84. B. jrondosa.
d. Involucri bracteae exteriores 10-16; interiores quam discus

breviores 85. B. vulgata.

b. Achaenia linearia, apicem versus saepe angustata.

c. Capitula perspicue radiata, floribus ligulatis saltern 8 mm. longis.
d. Ligulae albae vel ochroleucae . . . 132. B. pilosa var. radiata.
d. Ligulae flavae.

e. Folia petiolo adjecto 0.8-2.2 dm. longa; involucri bracteis
exterioribus 8-17; achaeniis cuneato-linearibus, corpore
4-7 mm. longis 100. B. aurea.

60 FIELD MUSEUM OF NATURAL HISTORY BOTANY, VOL. XVI

e. Folia petiolo adjecto plerumque 1.5-4 cm. longa; involucri
bracteis exterioribus 5-9 ; achaeniis interioribus linearibus
superne attenuates, corpore 6-9 mm. longis.

150. B. triplinervia var. macrantha.

c. Capitula discoidea vel debiliter radiata floribus ligulatis plerum-
que 2-6 mm. longis. ,
d. Folia simpliciter pinnata.

e. Involucri bracteae exteriores apicem versus plus minusve

dilatatae 132. B. pilosa et var. minor.

e. Involucri bracteae exteriores superne angustatae et non

dilatatae 126. B. biternata et var. glabrata.

d. Folia saltern foliolis imis 2-3-pinnata.
e. Flores tubulosi 4-lobati, achaeniis 6-13, biaristatis; folio-
rum segmentis linearibus vel oblongo-linearibus.

123. B. parviflora.

e. Flores tubulosi 5-lobati; achaeniis plerumque 15-35.
/. Foliola ima tripartita caetera indivisa, omnia ovata vel
lanceolata, multiserrata.

126. B. biternata et var. glabrata.
f. Foliola omnia 1-2-pinnata 115. B. bipinnata.

a. Plantae africanae.

b. Flores ligulati rubidi vel violacei vel purpurei nee (vel sicci

false) flavi nee albi.
c. Achaenia faciebus glabra; involucri b


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