The Annals, published quarterly, contains papers, primarily in systematic botany, contributed from the Missouri Botanical Garden, St. Louis. Papers originating outside the Garden will also be ac- cepted. Authors should write the Editor for information concerning arrangements for publishing in the Annals.

Editorl\l Committee

Nancy Morin, Editor Missouri Botanical Garden

Cheryl R. Bauer, Editorial Assistant

Missouri Botanical Garden

Marshall R. Crosby

Missouri Botanical Garden

Gerrit Davidse Missouri Botanical Garden

John D. Dwyer

Missouri Botanical Garden & St. Louis University

Peter Goldblatt

Missouri Botanical Garden

Colophon

This volume of the Annals of the Missouri Botanical Garden has been set in A Times Roman. The text is set in 9 point type while the figure legends and Uterati cited sections are set in 8 point type.

The volume has been printed on 70# Centura Gloss, an acid-free paper designed

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binding used in the production of the Annals is a proprietary method known as Permanent Binding.

The Annals is printed and distributed by Allen Press, Inc. of Lawrence Kansas 66044, U.S.A.

Missouri Botanical Garden 1985

ISSN 0026-6493

■

Anderson, Gregory J. The Evolution of Dioecy— Introduction 243

Armbruster, W. Scott & Ann L. Herzig. Partitioning and Sharing of

PoUinators by Four Sympatric Species of Dalechampia (Euphorbi- aceae) in Panama

Atwood, John T. A Floristic Study of Volcan Mombacho Department

of Granada, Nicaragua _ 1 9 1

AvERETT, John E. (See Shirley A. Graham & John E. Averett) 855

AvERETT, John E. & Peter H. Raven. Flavonoids of Onagraceae 30

Averett, John E. & Shirley A. Graham. Flavonoids of Rhynchocaly-

caceae (Myrtales) 853

Baas, Pieter. (See Ger J. C. M. van Vliet & Pieter Baas) 783

Baker, Herbert G. & Paul Alan Cox. Further Thoughts on Dioecism

and Islands

244

Barrett, Spencer C. H. Variation in Roral Sexuality of Diclinous Aralia

(Araliaceae)

278

Barringer, Kerry. A New Species of Guatteria (Annonaceae) from Pan-

ama

„ 1186

Duncan & Raymond B. Phillips. A Bib-

liography of Numerical Phenetic Studies in Systematic

Bawa, K. S. The Evolution of Dioecy— Concluding Remarks 294

Bawa, K. S. (See W. A. Haber & K. S. Bawa)

289

Behnke, H.-Dietmar. Ultrastructure of Sieve-element Plastids of Myr- tales and AlHed Groups

824

Bernhardt, P., J. Kenrick & R. B. Knox. Pollination Biology and the

Breeding System of Acacia retinodes (Leguminosae: Mimosoideae) .„. 17

Berry, Paul E. (See Joan W. Nowicke, John J. Skvaria, Peter H. Raven

& Paul E. Berry)

BouFFORD, David E. Circaea alpina L. (Onagraceae) in Thailand 1185

Briggs, B. G. (See L. A. S. Johnson & B. G. Briggs) 700

Carlquist, Sherwin. Wood and Stem Anatomy of Bergia suffruticosa:

Relationships of Elatinaceae and Broader Significance of Vascular Tra- cheids, Vasicentric Tracheids, and Fibriform Vessel Elements

Coetzee, J. a. & J. Muller. The Phytogeographic Significance of Some

Extinct Gondwana Pollen Types from the Tertiary of the Southwestern Cape (South Africa)

Cox, Paul Alan. (See Herbert G. Bake Crane, Peter R. (See David L. Dilcher

Crane, Peter R. & David L. Dilcher. Lesqueria: An Eariy Angiosperm

Fruiting Axis from the Mid-Cretaceous

1088 244

351

384

Crepet, William L. Advanced (Constant) Insect Pollination Mecha- nisms: Pattern of Evolution and Implications Vis-^-Vis Angiosperm Diversity

607

Crepet, William. (See David Dilcher & William Crepet) 348

Cronquist, Arthur. A Commentary on the Definition of the Order

Myrtales

780

Dahlgren, Rolf & Robert F. Thorne. The Order Myrtales: Circum

scription, Variation, and Relationships

633

Daniel, Thomas F. A Revision of Stenandrium (Acanthaceae) in Mexico

and Adjacent Regions

Davidse, Gerrit & R. P. Ellis. Steyermarkochloa unifolia, a New Genus

from Venezuela and Colombia (Poaceae: Arundinoideae: Steyermark- ochloeae)

Dedication

1028

994

347

348

Dilcher, David & William Crepet. Historical Perspectives of Angio-

sperm Evolution

Dilcher, David L. (See Peter R. Crane & David L. Dilcher) 384

Dilcher, David L. & Peter R. Crane. Archaeanthus: An Eariy Angio-

sperm from the Cenomanian of the Western Interior of North

America

351

Doebley, John F. Maize Introgression into Teosinte — A Reappraisal 1 1 00

Duncan, Thomas. (See Bernard R. Baum, Thomas Duncan & Raymond

B.Phillips) 1044

Dunn, David B. (See Ana Maria Planchuelo & David B. Dunn) 92

Ellis, R. P. (See Gerrit Davidse & R. P. Ellis) 994

Freeman, D. C, E. D. McArthur & K. T. Harper. The Adaptive Sig- nificance of Sexual Lability in Plants Using Atriplex canescens as a Principal Example 265

Friis, E. M. Preliminary Report of Upper Cretaceous Angiosperm Re- productive Organs from Sweden and Their Level of Organization 403

Gadella, T. W. J. Notes on Symphytum (Boraginaceae) in North Amer-

ica

1061

Gentry, Alwyn H. Klainedoxa (Irvingiaceae) at Makokou, Gabon: Three

mpatric Species in a Putatively Monotypic Genus 1 66

Gentry, Alwyn H. New Species and Combinations in Apocynaceae from

Peru and Adjacent Amazonia

1075

Goldblatt, Peter. New Species of Galaxia (Iridaceae) and Notes on

Cytology and Evolution in the Genus 1082

Goldblatt, Peter. (See Warren L. Wagner 8c Peter Goldblatt) 1 8 1

Goldblatt, Peter, James E. Henrich & Paul Rudall. Occurrence of

Crystals in Iridaceae and Allied Families and Their Phylogenetic Sig-

nificance

1013

Goldblatt, Peter, Virginia Walbot & Elizabeth A. Zimmer.

Estimation of Genome Size (C-Value) in Iridaceae by Cytophotome- try

176

Graham, Alan. Lisianthius Pollen from the Eocene of Panama 987

Graham, Shirley A. Alzateaceae, A New Family of Myrtales in the

American Tropics

757

Graham, Shirley A. (See John E. Averett & Shirley A. Graham) 853

Graham, Shirley A. & John E. Averett. Flavonoids of Alzateaceae

(Myrtales)

855

Haber, W. a. & K. S. Bawa. Evolution of Dioecy in Saurauia (Dillen-

iaceae) 289

Hampshire, Rachel «fe David Sutton. Alectra aspera (Cham. & Schlecht.)

L. O. Williams

1184

Harper, K. T. (See D. C. Freeman, E. D. McArthur & K. T. Harper) ..... 265 Haynes, Robert R. Techniques for Collecting Aquatic and Marsh

Plants

229

1013

Henrich, James E. (See Peter Goldblatt, James E. Henoch & Paul

Rudall)

Herzig, Ann L. (See W. Scott Armbruster & Ann L. Herzig) 1

HocH, Peter C. & Peter H. Raven. A New Combination for a North

American Epilobium 342

Holm-Nielsen, L. B. (See P. M. Jorgensen, J. E. Lawesson & L. B. Holm- Nielsen)

1172

HuFT, Michael J. A New Combination in Dalechampia (Euphorbia-

ceae)

341

HuFT, Michael J. A Review of Euphorbia (Euphorbiaceae) in Baja Cal-

ifornia

1021

Hughes, Norman F. Mesosperm Palynologic Evidence and Ancestors of

Angiosperms

P * ^» ^^^«^*4 • ^ VWH1

593

J0RGENSEN, P. M., J. E. LA WESSON & L. B. HOLM-NlELSEN. A Guidc tO

Collecting Passionflowers ._

1172

Johnson, L. A. S. & B. G. Briggs. Myrtales and Myrtaceae— A Phylo-

genetic Analysis .

700

Jones, Almut G. (See Porter P. Lowry II & Almut G. Jones) 1 1 28

Keating, Richard C. Leaf Histology and its Contribution to Relation-

ships in the Myrtales

801

Kenrick, J. (See P. Bernhardt, J. Kenrick & R. B. Knox) 17

Knapp, Sandra & James Mallet. Two New Species of Passijlora

from Panama, with Comments on Their Natural

History

1068

Knox, R. B. (See P. Bernhardt, J. Kenrick & R. B. Knox) 1 7

Krassilov, Valentin A. New Paleobotanical Data on Origin and Early

Evolution of Angio sperm y

P 4^#-*^^*^# V H^*^v ^^m.4

577

Lawesson, J. E. (See P. M. Jorgensen, J. E. Lawesson & L. B. Holm

Nielsen)

1172

LowRY, Porter P., II & Almut G. Jones. Systematics of Osmorhiza Raf.

(Apiaceae: Apioideae) ....

1128

McArthur, E. D. (See D. C. Freeman, E. D. McArthur & K. T. Har-

265

McDade, Lucinda a. Systematics and Reproductive Biology of the Cen- tral American Species of the Aphelandra pulcherrima Complex (Acan- thaceae)

Mallet, James. (See Sandra Knapp & James Mallet) —

Meagher, Thomas R. Sexual Dimorphism and Ecological Differentiation

of Male and Female Plants

104 1068

254

MoRLEY, Thomas. An Index to the Families in Engler and Prantl's "Die

Natiirlichen Pflanzenfamilien"

210

MULLER, J. (See J. A. Coetzee & J. Muller) 1088

MuLLER, Jan. Significance of Fossil Pollen for Angiosperm History 4 1 9

NowicKE, Joan W., John J. Skvarla, Peter H. Raven & Paul E.

Berry. A Palynological Study of the Genus Fmc/zs/a (Onagraceae) ... 35

Patel, Varsha C, John J. Skvarla & Peter H. Raven. Pollen Char- acters in Relation to the Delimitation of Myrtales 858

Phillips, Raymond B. (See Bernard R. Baum, Thomas Duncan & Ray- mond B. Phillips)

1044

Planchuelo, Ana Maria & David B. Dunn. The Simple Leaved Lu- pines and Their Relatives in Argentina 92

Raven, Peter H, The Order Myrtales: A Symposium 631

Raven, Peter H. (See Hiroshi Tobe & Peter H. Raven)

836

Raven, Peter H. (See Hiroshi Tobe & Peter H. Raven) 844

Raven, Peter H. (See Peter C. Hoch & Peter H. Raven) 342

Raven, Peter H. (See Varsha C. Patel, John J. Skvarla & Peter H. Ra- ven)

858

Raven, Peter H. (See Joan W. Nowicke, John J. Skvarla, Peter H. Raven

& Paul E. Berry) _

RuDALL, Paul. (See Peter Goldblatt, James E. Henrich & Paul

Rudall)

1013

Schaarschmidt, Friedemann. Rowers from the Eocene Oil-Shale of

Messel: A Preliminary Report

599

Schmid, Rudolf. Reproductive Anatomy and Morphology of Myrtales

in Relation to Systematics

Skvarla, John J. (See Varsha C. Patel, John J. Skvarla & Peter H. Ra- ven)

832

858

Skvarla, John J . (See Joan W. Nowicke, John J. Skvarla, Peter H Raven

& Paul E. Berry)

Steyermark, Julian A. Steyermark, Julian A.

Flora of the Venezuelan Guayana— I 297

New Rubiaceae from Venezuela 1175

Sutton, David. (See Rachel Hampshire & David Sutton) 1 184

Taylor, Charlotte M. Psychotria hebeclada DC. (Rubiaceae), an Over-

looked Species from Central America

169

Thanikaimoni, K. Principal Works on the Pollen Morphology of Myr-

tales

970

Thorne, Robert F. (See Rolf Dahlgren «fe Robert F. Thome) 633

TiFFNEY, Bruce H. Seed Size, Dispersal Syndromes, and the Rise of the

Angiosperms: Evidence and Hypothesis 5 5 1

ToBE, HiRosHi & Peter H. Raven. The Embryology and Relationships

of Alzatea Ruiz & Pav. (Alzateaceae, Myrtales) 844

ToBE, Hiroshi & Peter H. Raven. The Embryology and Relationships

of Rhynchocalyx Oliv. (Rhynchocalycaceae)

836

Upchurch, Garland R., Jr. Cuticle Evolution in Early Cretaceous An-

giosperms from the Potomac Group of Virginia and Maryland 522

Upcoming Meetings

AETFAT

Second International Legume Conference

343 343

Vliet, Ger J. C. M. van & Pieter Baas. Wood Anatomy and Classifi-

cation of the Myrtales

783

Wagner, Warren L. Reconsideration of Oenothera Subg. Gauropsis

(Onagraceae)

1114

Wagner, Warren L. & Peter Goldblatt. A Survey of Seed Surface

Morphology in Hesperantha (Iridaceae)

181

Walbot, Virginl\. (See Peter Goldblatt, Virginia Walbot & Elizabeth A.

Zimmer)

176

Walker, Audrey G. (See James W. Walker & Audrey G. Walker) 464

Walker, James W. & Audrey G. Walker. Ultrastructure of Lower Cre-

taceous Angiosperm Pollen and the Origi Flowering Plants

464

Werff, Henk van der. Notes on Neotropical Lauraceae 11 80

Zavada, Michael S. Angiosperm Origins and Evolution Based on Dis-

persed Fossil Pollen Ultrastructure

444

I, Elizabeth A. (See Peter Goldblatt, Virginia Walbot & Elizabeth Zimmer)

176

THE

UME71

1984

NUMBER 1

Hcnij Shaw {1800-1889)

F ^mv^^^ Yw^^^j^K :

Corn us kousj

CONTENTS

Partitioning and Sharing of Pollinators by Four Sympatric Species of Dal-

echampia (Euphorbiaceae) in Panama W. Scott Armbruster & Ann

L. Herzig 1

Pollination Biology and the Breeding System of Acacia retinodes (Legumi-

nosae: Mimosoideae) P. Bernhardt, J. Kenrick & R. B. Knox 1 7

Flavonoids of Onagraceae John E. Averett & Peter H. Raven 30

A Palynological Study of the Genus Fuchsia (Onagraceae) Joan W. Now-

icke, John J. Skvarla, Peter H. Raven & Paul E. Berry 35

The Simple Leaved Lupines and Their Relatives in Argentina Ana Maria

Planchuelo & David B. Dunn „ 92

Systematics and Reproductive Biology of the Central American Species of

the Aphelandra pulcherrima Complex (Acanthaceae) Lucinda A. McDade 104

Klainedoxa (Irvingiaceae) at Makokou, Gabon: Three Sympatric Species in

a Putatively Monotypic Genus Alwyn H. Gentry... „ 166

Psychotria hebeclada DC. (Rubiaceae), an Overlooked Species from Central

America Charlotte M. Taylor 169

Estimation of Genome Size (C- Value) in Iridaceae by Cytophotometry

Peter Goldblatt, Virginia Walbot & Elizabeth A. Zimmer 176

Contents continued on back cover

VOLUME 71

1984 NUMBER 1

OF THE

mmi

primarily in systematic

ssouri Botanical Garden. Papers originating outside the Garden will also be accepted. Authors should write the

formation concerning arrangements

the Annals.

Editorial Committee

Nancy Morin, Editor Missouri Botanical Garden

Cheryl R. Bauer, Editorial Assistant

Missouri Botanical Garden

Marshall R. Crosby Missouri Botanical Garden

Gerrit Davidse Missouri Botanical Garden

Missouri

John D. Dwyer

Peter Goldblatt Missouri Botanical Garden

informat

P.O. Box 299, SL Louis, MO 63166.

SiTO .11 ^^^^"^'""P^*^" price is $60 per volume U.S., $65 Canada, and Mexico

299, St. Louis, MO 63166.

Missouri Botanical Garden 1 984

OF THE

1859* 1984

Missouri Botanical Garden

VOLUME 71

1984

George Engelmann in 1860.

This volume of the Annals is dedicated to George Engelmann (1809-1884), who, though never formally associated with the Missouri Botanical Garden, was influential in establishing a program of scientific research here.

Engelmann was bom in Frankfort-am-Main in the same year that Abraham Lincoln was bom southwest of Frankfort, Kentucky, and Charles Darwin was bom in England. His involvement with the Burchenschaft, a liberal German fratemal organization, caused his migration from the University of Heidelberg, to Berlin, to Wurzburg, where he received his medical degree in 1831. He then

spent a few months in Paris renewine old universitv acnuaintanres with T niiis

imper

mic

in the fall of 1832 as an emissary for his family, to investigate the advisability and feasibility of immigration to Das West/and.

The next two plus years were spent investigating and exploring western Illinois, Missouri, and Arkansas. By the fall of 1835 he was flat broke and established a medical practice in St. Louis with the goal of earning enough money in a few years to return permanently to Germany. But he never did. His medical practice boomed, because the population was growing rapidly, doubling every few years, due in no small part to German immigration, and, probably, because his European training was better than that of most local practitioners. In 1 840 he returned to Germany to marry his long-time sweetheart, Dorothea Horstmann. On the return trip to St. Louis, Engelmann met Asa Gray in New York, establishing a close working relationship that would last the rest of his life.

The first of Engelmann's many publications on North American botany ap- peared in 1 842, "A monography of North American Cuscutinae," in the American Joumal of Science, "Silliman's Journal." Engelmann participated in the foun- dation of St. Louis's Western Academy of Science in 1835, and he, Adolphus Wislizenus, William Greenleaf Eliot, and Marie P. Leduc attempted to establish a botanical garden near the southwestern edge of the city in 1843. These ideas were, perhaps, just a bit ahead of their time: neither institution lasted long or contributed significantly to the advance of knowledge. However, by the late 1850's things had changed: in 1856 Engelmann was a founder of the St. Louis Academy of Science, which survives today as the St. Louis Museum of Science and Natural History, and he helped mold Henr>' Shaw's concept of a Botanical Garden to include a herbarium and library. Shaw opened his Missouri Botanical Garden to the public in 1859, and among its most handsome features was the Botanical Museum & Library, in which was installed the herbarium of J. J. Bernhardi of Leipzig, which Engelmann had Durchased on Shaw's behalf for $400 while on an

Bemhard

imens.

gelmann maintained a demanding medical

medici

1863

Congressionally established National Academy of Sciences in

mem

him

Monographic publications continued to pour from his steel pen until shortly before his death. Cuscuta was not the only difl^cult, tedious group on which he Worked. Indeed, he concentrated his efforts on such groups: Qiicrcus. Vitis, Cac- taceae, conifers, Isoetes. His detailed studies of these and other taxa laid the foundations for future workers.

hngelmann also contnbuted indirectly to our understanding of plants by acting as a middle-man between the West and the East. Strategically positioned in St. Louis, the gateway to much western trade, exploration, migration, and adventure, he hired and trained individuals— Joshiah Gregg, Ferdinand Lindheimer, Au- gustus Fendler— to collect and advised military leaders— John Charles Fremont, William Emory— as they lead their troops west, assuring a steady flow of spec- imens moving from the hitherto unexplored West to the botanical centers of the East, especially into the hands of John Torrey and Asa Gray.

The Thirtieth Annual Systematics Symposium, held at the Missouri Botanical Garden on 19 and 20 October 1984, also commemorated George Engelmann, concerning itself with our current knowledge of many of the taxa he studied, southwestern floristics, and his life and relations with contemporaries. The pro- ceedings of the Symposium will appear in a future issue of the Annals.

OF THE

VOLUME 71

1984

NUMBER 1

PARTITIONING AND SHARING OF POLLINATORS BY

FOUR SYMPATRIC SPECIES OF DALECHAMPIA

(EUPHORBIACEAE) IN PANAMA ^

W. Scott Armbruster^ and Ann L. Herzig^

Abstract

Observations were made on distribution, floral morphology, and pollination of four species of Dalechampia (Euphorbiaceae) in central Panama. The four species occur sympatrically in various combinations throughout Panama and are pollinated by resin-collecting euglossine bees, and resin- and/or pollen-collecting stingless bees and megachilid bees. With one exception, these plant species overlap very little in pollinators or time of pollination. Dalechampia heteromorpha is pollinated early in the day by Trigona and Hypanthidium whereas a sympatric congener, D. scandens, is pollinated by the same species of bees late in the day. A third sympatric species, D. dioscoreifoUa, is pollinated by euglossine bees. Dalechampia heteromorpha also occurs sympatrically with D. tiliifolia\ the latter is pollinated by euglossine bees. Individuals of Dalechampia dioscoreifolia and D. tiliifolia were observed occurring together at only one site; here they shared pollinators (euglossine bees) and were receptive to pollination at the same time of day. Interspecific pollen flow was substantial and may have resulted in depressed seedset in D. dioscoreifolia.

ggested

communities are likely to be organized in ways that minimize reproductive interference (Levin,

Levin & Anderson, 1970; Mosquin

[W.

term

»»

to mclude all plant-plant interactions that have direct detrimental eflfects on reproductive pro- cesses, including competition for pollinator ser-

mterspe

dispersal

inclusive than the phrase "competition for pol- lination" used by Waser (1 982).] There have been a number of studies that indicate such organi- zation occurs in natural communities (Snow, 1966; Frankie, 1975; Reader, 1975; Heinrlch, 1976a; Stiles, 1975, 1977;Feinsinger, 1978; Wa- ser, 1978a; Brown & Kodric-Brown, 1979; Par- rish & Bazzaz, 1979). However, as several au- thors have pointed out, before claiming that organizing processes have affecled community structure it is necessary to show statistically that

Don Windsor

Dressier for assistance in Panama, Irene Baker for information on the paints, Kim Steiner anc er for information on distribution and Dhenolocy, Robert Dressier for identifying euglossine bees

Karen Harris for assistance in makmg greenhouse crosses

Ackerman, John Bryant, Terry Chapin, Steve MacLean, Kim Steiner, Ed Murphy, Grady Webster, Cheryl

valuable

supported by grant

Department of Botany, University of California. Davis, California 95616. Present address: Department of Biology, Fisheries and Wildlife and Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 9970 L

r r

Ann. Missouri Bot. Card. 71: 1-16. 1984.

ANNALS OF THE MISSOURI BOTANICAL GARDEN

[Vol. 7 1

niche overlap in a community is less than that sequently there is a bisexual phase during which

of a randomly generated assemblage of species the pistillate flowers are still receptive, but the

(Connor & Simberloff, 1979; Poole & Rathcke, staminate flowers are also open and pollen is

1979; Strong et al., 1979). Further, as Grant being shed. During the bisexual phase self-pol-

(1972), Roughgarden (1976), Feinsinger (1978), lination may occur; since all Z)a/^c/zflmpza species

Slatkin (1980), Waser (1983), and others have that have been tested are self-compatible, self-

pointed out, the observed organization may be

(Armbruster

either the result of evolution of the component During the pistillate phase only cross-pollination species in response to their biotic environments is possible.

or the result of the sorting of preadapted species

Most species of Dalechampia are pollinated

into "compatible" associations. It is difficult, at by female bees that collect the resins secreted by best, to distinguish between these two processes. the large secretory glands associated with the sta-

These limitations notwithstanding, we believe

(Armbruster & Webster,

that it remains useful to investigate the ecological 1981, 1982). The amount of resin secreted de- relationships between members of species as- termines the size of the largest floral visitors, semblages. While detailed studies of a single Apparently due to energetic constraints on for- community usually cannot demonstrate com- aging behavior, only small bees visit Dalecham- munity organization, they may reveal the selec- pia species that secrete small amounts of resin, tive pressures that have been operating and the whereas large bees (euglossines) visit only those

"cost" of not being adapted to sympatry. We have been interested in how assemblages

species of Dalechampia bearing larger amounts of resin (Armbruster & Websten 1981, 1982;

of sympatric species of Dalechampia (Euphor- Armbruster

biaceae) are organized, especially with respect to

Because of the viscous, sticky nature of floral

shown

use of the pollinating fauna and to potential in- resins, it is very difficult to measure the rate of

terspecific pollen flow. The pollination systems resin secretion. Experimental removal of resin

of three different pairs of sympatric species of from glands of D, scandens, D. heteromorpha,

Dalechampia in South America and Mexico have and D. tiliifolia has

been discussed by Armbruster and Webster (1979, occurs throughout the period that the bracts are

1981, 1982). In each case the pollinators were open, and about 0,5-1.5 mm (depth) of resin

effectively partitioned, and there was very little accumulates across the surface of the gland daily

interspecific pollen flow. In this paper we de- (Armbruster, unpubl.). Dalechampia dioscorei-

scribe the relationships between four species of folia appears to follow this pattern as well. Be-

Dalechampia (D. dioscoreifolia, D. heteromor- cause the rates of secretion are similar in all

pha, D. scandens, and Z). tiliifolia) that occur in species studied and because of the difficulties in

several combinations ofsympatry in Panama and measuring secretion rates, the area of secretion

examine the relationships with pollinators, the is probably the best single field measurement of

extent of resource partitioning, and the amounts the average quantity of resin available to foraging

of interspecific pollen flow.

bees

Z)a/^c/2awp/a contains about 100 species, most The arrangement of the staminate and pistil- of which are small to moderate-sized lianas of late flowers also aflfects the size class of the ef- lowland neotropical habitats. All species are fective pollinators. Species of Dalechampia in monoecious; the unisexual flowers are grouped which the distances between the gland and the together into functionally bisexual pseudanthial stigmas or the gland and the anthers is relatively inflorescences (Webster & Webster, 1972). In large (>ca. 6 mm) are pollinated only by rela- most species studied, including those considered tively large bees (>ca. 10 mm). Species of Dale- here, the inflorescence contains three pistillate champia in which the gland-stigma and gland- flowers, 8-13 staminate flowers, and a gland-like anther distances are smaller (<ca. 4 mm) can be structure that secretes resin (Armbruster & Web- p ster, 1 979). The whole inflorescence is subtended si by two usually large and showy bracts.

In most species of Dalechampia, including the subjects of this study, the pistillate flowers are

(Armbruster & Web

ster, 1981, 1982; Armbruster, in prep.).

Materials and Methods

Observations on the reproductive biology of recepUve several days prior to anthesis of the Dalechampia species were made in the Canal stammate flowers in the same inflorescence. Sub- Zone of the Republic of Panama during three

1984]

ARMBRUSTER & HERZIG-DALECHAMPIA

separate periods: 30 June-3 July 1978, 14-18 throughout

January

e observations dioscoreifolia I

eluded in calculating means. To assess the move-

within

sta-

pha Pax & Hoffmann (Pax & Hoffmann, 1919; D. cissifolia subsp. panamensis, Webster & Burc

1968; Croat, 1978), and D. scandens L., where granules

minate flowers of each species were dusted at short intervals with specific colors of powdered, non-toxic, fluorescent paint; transfer of paint

they occurred together at km 1 3 Pipeline Road. Intensive observations were also made on Z). dioscoreifolia, D. heteromorpha, and D. tiliifolia Lam. where they occurred together at km 15 Pipeline Road. Additional

observations

made on these species at 10 other sites in the

plant species and floral visitors were collected. In the lab pollen loads were removed from vis- itors, slides made using Hoyer's medium, and pollen identified with a microscope. Plant vouch- ers have been deposited at DAV and SCZ. Experimental intraspecific and interspecific

Canal Zone, including elsewhere along Pipeline crosses, measures of selfing ability and stigmatic

Madden

Madden Reserve, Barro ( near the Summit Gardens.

receptivity, and tests of self-compatibility were performed on cultivated material of all four species in the greenhouses at the University of

tagged 19-52 inflores- California, Davis from 1975 until 1980. Crosses

daily

were made by removing all staminate flowers

mnumberofstaminate flowers open, amount of while in bud and manually transferring pollen resm present, and the amount and, when pos- with a small camel's-hair brush. Stigma recep- tivity was tested by pollinating stigmas in emas- culated inflorescences at various times during in-

type of pollen on the stigmas

observing

gland. Pollen grains, which are large (ca. 50-150 florescence development and by testing for

peroxidase activity with Peroxtesmo KO paper

with

lens; we were able to distinguish between the pollen of Z). tiliifolia and D, dioscoreifolia on the basis of size. Dalechampia pollen was distin- guishable from pollen of other plants common in the area on the basis of size and color. At half-

Results

DISTRIBUTION AND FLOWERING TIME

intervals

Measurements

dioscoreifolia

i Z). tiliifolia i

and/or open

gland

While

gland

anthers, and the anthers and stigmas, using dial calipers accurate to 0,05 mm.

VJbSerVationS nn nr*llinQtrvT-c inr-lnH^H r^/Mirttino

majority of the 12 study sites only one or two

st>ecies

observe three species occurring

dioscoreifolia

floral visitors, noting the amount and color of sympatrically with A A^/^-wmorpAa at four sites, their corbicular/scopal loads, recording their be-

with

havior and monitoring their movements. To fa- heteromorpha occurred with Z). scandens at one

ciutate these observations some bees were cap- site

tured, marked on the scutum with correction pia

fluid, and released. Effectiveness of pollinators get]

^as determined bv monitnrino rhnnaf-*: in mim- tn t

and with D. tiliifolia at two site dioscoreifolia and D. tiliifolia er at one site, but Z>. tiliifolia ^

scrub, whereas D. dioscoreifolia

berofpoUen grains on the stigmas of each species; curred in the forest (Table 1). The two species effective pollinators (Table 3) are those that were

observed

grew

scrub

stigmas

The data on flowering phenology of Panama-

calculated for each pollinator species by sum- nianDiz/^cAam/?/^ are limited; however, it is pos-

and dividing sible to make a first approximation based on our

observed umber of days of observation

observations

"^ean number of inflorescences open in the ob- lections, and from the literature. The phenolog- nervation area during the period of observation, ical data presented in Table 2 are based on our

observations

ANNALS OF THE MISSOURI BOTANICAL GARDEN

[Vol. 7 1

Table 1.

Panama.

central

D» dioscoreifolia D, heteromorpha

Site:

km 13, Pipeline Rd. km 15, Pipeline Rd. km 17, Pipeline Rd. Madden Reserve Madden Dam Summit Gardens Barro Colorado Island

Habitat:

Closed Forest Open Forest Forest Edge Secondary Scrub Open Fields

+ +

+ + +

D. scandens

+ +

D. tiliifolia

+ + +

vember and January, nearly year-round obser- bars of the population produce new flowers vations of K. E. Steiner (pers. comm.), Croat's throughout the blooming season.

observations (1978), and examination of Pana-

Three of the species of Dalechampia bloom

manian specimens from SCZ, MO, and GH primarily during the late wet and dry seasons {Dalechampia dioscoreifolia: 5 sheets; D. hetero- and reproductive interference between members morpha: 4 sheets; D. scandens: 3 sheets; D, ti- of each sympatric species could be occurring at liifolia: 1 8 sheets). These data are further cor- this time. Thus, there is potential reproductive roborated by our observations made on these interference with congeners affecting D. tiliifolia, four species in other parts of Mesoamerica and D. scandens, and possibly D. dioscoreifolia northern South America intermittently from 1975 throughout the flowering season of each. How- to 1980. Considerable phenological information ever, since D. heteromorpha blooms year-round, can be gleaned from examination of natural pop- it may not be subject to reproductive interference ulations, even at a few times of the year: the from other species for about half of the year (cf previous 1-3 months' flowering activities are re- Table 2). corded in fruits of various stages of maturation or dehiscence; the future month of flowering ac- tivities can be predicted by examining plants for Greenhouse

BREEDING SYSTEMS

inflorescence buds. In all four species (as studied shown

field bagging experiments

throughout the Neotropics), all ''mature" mem- Z>. scandens, and D. tiliifolia are self-compatible.

Table 2. Flowering phenology of Dalechampia species in central Panama. Table is based on personal

information presented in Croat, 1978, and verbal reports (K

3W Ackerman. 1984. (-\- indf rates ahnndant flnw*»rino r»i-r-ii

month.)

Dry

Species

Jan Feb Mar

D. dioscoreifolia D. heteromorpha

D. scandens D. tiliifolia

+ +

Season and Month

Early Wet

Mid Wet

Apr May Jun

Jul Aug Sep

-f?

Late Wet

Oct Nov Dec

+ + + +

+ +

1984]

ARMBRUSTER & HERZIG-DALECHAMPIA

Table 3. Floral morphology of Panamanian Dalechampia. Numbers in table are means ± s.d. with N in parentheses.

Dalechampia Species

Number ofSta- minate

Flowers

D. dioscoreifolia D. heteromorpha D. scandens D. tiliifolia

8-10 8-10 9-10 9-10

Gland Area (mm^)

Gland-Stigma

Distance (mm)

Gland-Anther Distance

(mm)

30.1 6.5 8.7

22.0

12.3 (20) 1.8 (16) 3.0 (30) 4.8 (20)

5.5 ± 1.1 (20)

6.7 ± 1.5(10)

3.1

0.6 (16)

3.1 ± 0.8 (29)

8.9

1.7 (20)

2.2 2.8 8.2

0.4 (9) 0.8 (20) 1.0(15)

Anther-Stigma

Distance

(mm)

10.2 0.5 1.8 3.0

2.0 (9) 0.6 (9) 0.8 (20)

2.1 (15)

All four of these species set nearly full comple- mean anther- stigma distance (10.2 mm, Table

ments of seeds when inflorescences are manually 3). This strongly suggests that self-pollination in

self-pollinated and screened from pollinators, the absence of pollinators is rare. In one plant

There are, however, differences among species screened from pollinators in the greenhouse only

with respect to the ability of each to self-pollinate two out of eight inflorescences set seed. A closely

and set seed in the absence of pollinators. Ob- related species, D. aristolochiifolia H.B.K. has a

servations of pollen movement in a number of similar inflorescence morphology (distances be-

species have shown that the distance between the tween gland-stigma =5.8 mm, gland-anther =

nant 9. 1 mm, anther-stigma = 7 mm; compare with

trm- Table 3) and set no seed when grown in the green-

pnmary determ

house and screened from pollinators (N

108).

FLORAL DEVELOPMENT

bruster, in prep.). Accordingly, D. hetc ^.™

with a mean anther-stigma distance of only 0.5

mm (Table 3) sets abundant seed in the absence

of poUinators. Plants screened from pollinators The four species of Dalechampia considered

in greenhouse experiments produce 68% of the

patterns

Manually cence development (Table 4). The involucral

selfed material had seedsets of 85% of maximum bracts remain closed when the inflorescences are

603), so depression of seedset by the lack

open

iP < 0.001, d

normal

gnificant stigmas of all four species are receptive. Seed was

set in greenhouse material of D. heteromorpha.

binomial distribution; Bailey, 19 59), is relatively D, scandens, and D. tiliifolia

small.

openmg

Dalechampia scandens also has a relatively emasculated and screened from pollinators. All small mean anther-stigma distance (1.8 mm, Ta- " '^ "^^ '''*"''^ ^-^^^;^o.« ..o.*;^«.

species

of this species grown

abundant

on the first day of bract opening. Similar tests

through

sence of pollinators. A population of J9. scandens out the period of anthesis of the staminate flow- in Costa Rica with a mean anther-^itipma dis- ers.

tance of 3.6 mm produced 63% of maximum possible seedset (N = 27) when screened from

Anthesis

Pollinat

27) when screened from on the second to fourth day after the bracts first

tiliifolia

days open

^ean anther-stigma

persist

and self.poUination when pollinators are absent anthesis and then abscise. Anthesis of the ^ay be relatJv^iw f..o^„^«+ t,. « ^^ — iot;^« ;r> tur**" ctaminate flowerfs) occurs shortly afi

ma-

ture" staminate flower(s) occurs shortly after the

open each day (Table 4). In all four species.

^f 2 mm, inflorescences screened from pollina- the anthers dehisce shortly after anthesis.

tors produced 93% of maximum possible seed- The '—'—' ^--*- ---- ^"^ ^^^^ ^" set rM = o^x ^ ,

(N = 84).

dioscoreifc

species

open cle characteristic for each of the four species )racts of A heteromorpha open daily in th< morning, those of D. scandens in the earlj

ANNALS OF THE MISSOURI BOTANICAL GARDEN

[Vol. 7 1

Table 4. Inflorescence development and behavior. Numbers in columns 1 and 2 are means rounded to the nearest day with range and sample size in parentheses.

Species

D. tiliifolia

Duration of 9 Phase (days)

D. dioscoreifolia D, heteromorpha D, scandens

3 (2-5; 8) 3 (2-4; 9) 2(1-3; 10) 2 (1-3; 6)

Duration of § Phase (days)

4 (3-6; 4)

5 (4-6; 7)

6 (5-6; 8) 5(5-6; 11)

Time of Anthesis of

Staminate

Flowers

(hrs)

ca. 1500 ca. 0700 ca. 1330 ca. 1430

Period Bracts

Are Open

(hrs)

(1400) 1500-1830 0600-1 900(+)

(1300) 1330-1830 1400-1800

afternoon, and those of Z). tiliifolia and D, dios-

The size of the stigmatic tip of the stylar col-

core//b//fl in the early to mid-aftemoon. The bracts umn also varies considerably among the four

of all four species close shortly after sunset (Table species. In Dalechampia heteromorpha this

4). structure is relatively small (ca. 0.7 mm^); in D.

In all four species, after ca. seven to nine days scandens it is slightly larger (ca. 0.8 mm^). In

of receptivity, the inflorescence passes into the fruiting phase. The staminate cycle, including the

Dalechampia tiliifolia and D, dioscoreifolia the stigmatic tips are considerably larger (ca. 4 mm^

resin gland, abscises. The bracts in D, hetero- and ca. 6 mm^, respectively).

morpha, D. scandens, and D. tiliifolia close

around the developing capsules. In the last two

species the bracts suffuse with chlorophyll. In D.

dioscoreifolia the bracts abscise when the fruits

begin to develop (cf. Armbruster, 1982).

POLLINATION AND SEEDSET

As predicted from studies of other species of Dalechampia (cf. Armbruster & Webster, 1981, 1982), D. heteromorpha and D, scandens (both with small resin glands) were visited only by small

bees, including Hypanthidium panamense and The basic number and arrangement of sta- Tr/gowa spp. (Table 5). These bees collected resin

minate and pistillate flowers in the inflorescences and/or pollen. We observed no visits by the larg- is similar in all the four species considered in this er euglossine bees during 42 hours of observation

INFLORESCENCE MORPHOLOGY

although

gland

bees

study (Table 3, Figs. 1-4). However, there is con- at the Pipe

siderable variation in the color and size of bracts, bees were s

in the size of the resin glands, and in the distances stigma and

between floral structures. Dalechampia hetero- bothofthes

morpha has relatively small green bracts (10-25 effectively transferred pollen to the stigmas. Pol- len was deposited on the legs and ventral surface of the thorax and abdomen. The same species pollinated D. scandens and Z). heteromorpha at

glands

gland

Similarly, D.5Cfl^J^n5 has relatively small, pale- other study sites where these plants were ob- green bracts (10-25 mm), and relatively small served.

resin