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Home , Achatocarpaceae, Amaranthaceae, Atriplex rosea, Basella, Cerastium, Cerastium glomeratum

lnterfamilia/Relationships of Cactaceae within the Dicot Order,

by

James E. Oliver

A Thesis Submitted to the Faculty of the

Charles E. Schmidt College of Science

in Partial Fulfillment of the Requirements for the Degree of

Master of Science

Florida Atlantic University

Boca Raton , Florida

December 1998 lnterfamilial Relationships of Cactaceae ~vithin the Dicot Order, Caryophyllales

by

Jarne.s E. Oliver

Tt·ds thesis was prepamd ur.dor the direction of the candidate's thesis advisor,

Dr. David M. Binninger, Department of Bioiogic:a: SGi ence, and has t-,efm c..pproved by members of his supervisoiy comm ittAG lt wa.s submitted to th0 f;:~cu!ty of t;·,e Cr,ar ies E. Schmidt College of Sc1ence and was accepmd as

~~ ailial fulfillment of the requirements for the dsg:-ee of Master of Sc;snce.

S UPERVIS08'r' COMiVliTTc~ :

1-Jd.-70 ---'---~ - · -.. - ~--~. · --·- ·· ·- -· - J O::;, t ~

il Acknowledgments

I would like to thank my advisors, Dr. David Binninger, Dr. Daniel Austin and Dr. Ralph Adams for their patience and guidance in enabling me to complete this project.

I also want to give special thanks to Chris Doughtery for his work in generating the genetic sequence data that made my research possible.

ill Abstract

Author: James E. Oliver

Title: lnterfamilial Relationships of Cactaceae within the Dicot

Order, Caryophyllales

Institution: Florida Atlantic University

Thesis Advisor: Dr. Daniel F. Austin and Dr. David M. Binninger

Degree: Master of Science

Year: 1998

The position of the family, Cactaceae, within the order Caryophyllales was examined by outgroup analysis of chloroplast rbcL gene sequence data. Comparative data came from 28 outgroup in 15 families and six ingroup species. Phylogenetic Analysis with P AUP 3.1 produced twelve equally parsimonious ; these were used to generate a strict consensus . MacClade 3.06 was used to refine the polytomies in the consensus tree. Analysis indicates that the Cactaceae is a monophyletic clade; moreover, these results support the work of other analyses that the sister family to Cactaceae is the . Other relationships within the order are not completely consistent with previous studies. For example and occupy a central position in the cladogram; aligns with the and Chenopodiaceae; and is presented as the basal family within the

lV order. Lastly, the Jamaican cactus Opuntia spinosissima was derived from a common ancestor with the Florida Keys endemic, Opuntia corallicola.

Key Words: Cactaceae, Caryophyllales, chloroplast rbcl gene, polytomies, monophyletic

v Table of Contents Page List of Tables ...... vii

L1st. ofF' 1gures ...... Vlll...

Introduction ...... ! Hypothesis ...... 8 Materials and Methods ...... 9

Results ...... lO

Discussion ...... 18 Literature Cited ...... 23

Vl List of Tables Page

Table 1. Taxa, Sources and Accession Numbers for rbcL Data ...... 3

Vll List of Figures Page

Figure 1. Cronquist's 1981 Arrangement of Families Within the Caryophyllales ...... 6 Figure 2. Strict Consensus of 12 Equally Parsimonious Trees Generated with PAUP 3.1 ...... 12 Figure 3. MacClade 3.06 Soft Polytomy Resolution of Strict Consensus Tree ...... 14 Figm·e 4. MacClade 3.06 Hard Polytomy Resolution of Strict Consensus Tree ...... 16

viii To my family and friends, whose faith in me and support made this possible.

lX Introduction

Morphological, chemical, and molecular characters indicate that the dicot order, Caryophyllales, comprised of 12 families (Table 1) and ca. 10,000 species, is monophyletic (Cronquist 1988; Downey and Palmer 1994; Downey et al. 1997). Past investigations have distinguished the order on the basis of specific embryological features (Cronquist 1988); the presence of unique sieve tube plastid elements; and the replacement of anthocyanin pigments with the class of pigments called (Gibson and Nobel1986). Another widespread but unique characteristic of the order, though not present in

Cactaceae, Portulacaceae, or Didieraceae, is anomalous secondary thickening of successive cambia (Gibson and Nobel1986).

Nevertheless, the position of Cactaceae and its sister group is still debated (Downey and Palmer, 1994; Hershkovitz and Zimmer, 1997).

Cronquist's (1981) arrangement of the order placed Caryophyllaceae and

Molluginaceae basally with the remaining 11 families derived from

Phytolacaceae (Figure 1). Cronquist (1988) grouped Cactaceae with

Aizoaceae and Didieraceae as a trichotomy and aligned Portulacaceae with

Basellaceae (Figure 1). Some evidence suggests that the sister taxon to the

Cactaceae is either the Portulacaceae (Gibson and Nobel1986; Downey and

Palmer 1994; Hershkovitz and Zimmer 1997), (Rodman 1984) or

1 (Gibson and Nobel1986). Other studies put Cactaceae and

Didiereaceae in an alliance of Aizoaceae, Portulacaceae and Basellaceae

(Rodman 1984).

Many of the uncertainties regarding the interfamilial relationships within

Caryophyllales may be attributed to the various methods employed in arranging the families (Downey and Palmer 1994). This variation was demonstrated by Dougherty (1996) in which chloroplast rbcL gene sequence data were used to construct phylogenies to delineate the species status of an endangered cactus. The rbcL gene is useful because it contains >1400 base pairs for comparative information and its rate of evolution is appropriate for phylogenies at the subfamiliallevel and higher (A vise 1994; Bayer et al. 1996).

However, certain representative species of Caryophyllales failed to align with those of Cactaceae according to traditional taxonomic arrangements

(Dougherty 1996). The apparent grouping of cacti away from other species of the order suggests that cacti represent a separate clade (Dougherty 1996).

2 Table 1. Taxa, Sources, and Accession Numbers for rbcl Data Used in the Study.

3 Taxa Accession 1 Outgroupllngroup Source Number Family Species 1 Achatocarpaceae I spinescens GenBank M97887 Outgroup

2 Aizoaceae I Lithops ~ GenBank M97889 Outgroup 3 Aizoaceae I Mesembryan- crystallinum GenBank M98515 Outgroup themum 4 Aizoaceae Trianthema portulacastrum GenBank M62572 Outgroup 5 Amaranthaceae Amaranthus hypochondriacus GenBank X51964 Outgroup 6 Amaranthaceae GenBank X53980 Ou!grOUIJ 7 Basellaceae Base II a alba GenBank M62564 Outgroup *"" 8 CC!rYopl}yllaceae Arenaria drummondii GenBank M83541 Outgroup 9 Caryophyllaceae glomeratum GenBank M83542 Ou!group 10 Caryophyllaceae Silene gallica GenBank M83544 Outgroup 11 I Caryophyllaceae Dianthus caryopl"lyll us GenBank M77699 Ou!_g_roup 12 I Chenopodiaceae A triplex petula GenBank M33795 Outgroup 13 I Cheno_Qodiaceae AtrlQiex rose a GenBank M33794 Outgroup 14 I Chenopodiaceae oleracea GenBank J01443 Outgroup V00168 15 Didiereaceae Alluaudia pro cera GenBank I M62563 Ou!grQI.!P

16 Moll~naceae verticillata GenBank I M62566 Outgroup 17 Nyctaginaceae Bougainvillea _g!abra GenBank I M88340 Outgroup 18 Nyctaginaceae Mirabilis jalapa ! GenBank I M62565 Outgroup Taxa Source Accession Outgroupllngroup Family Genus Species Number 19 Ph_ytolaccaceae pharnacioides GenBank M97890 Outgroup 20 americana GenBank M62567 Outgroup 21 Phytolaccaceae humilis GenBank M62569 Outgroup 22 Ph_ytolaccaceae halimifolium GenBank M62571 Outgroup 23 Plumbago capensis GenBank M77701 Outgroup 24 Polygonaceae Rheum xcultorum GenBank M77702 Outgroup 25 Portulacaceae grandiflora GenBank M62568 Outgroup 01 26 Sarraceniaceae GenBank L42211 Outgroup 27 Sarraceniaceae nutans GenBank L02433 Outgroup 28 Sarraceniaceae Sarrracenia flava GenBank L01952 Outgroup 29 Cactaceae Cereus pentagonus Daugherty FAU OP-4 lngroup 30 Cactaceae Opuntia corallicola Daugherty FAU OP-9 lngroup 31 Cactaceae O_Q_untia s_pinosissima Daughe_rty FAU OP-8 lngroup 32 Cactaceae Opuntia spinosissima Daugherty FAU OP-23 lngroup 33 Cactaceae Pereskia aculeata Genbank M97888 lngroup 34 Cactaceae Schlu'!lbe_r-_ger'!_ truncata Genbank M83543 L__ lngroup ·-·· _ - ---· - - --· - ·------Figure 1. Cronquist's 1981 arrangement of families within the Caryophyllales

6 r------~~----~-----~~-----~--~--~, I I : s. Dldiereaceae CARYOPHYLLALES I I I I I I I I 4. Alzoaceae 8. Cactaceae J I I I I ~ ;{ 7. Cbonopodlac.. o I

3. Nyctaglnaceaa a Amaranthacaaa

-.:)

2. Achalocarpacaaa

11. Molluglnacau

12. Caf)'OC)hyHacaat L------..------..------Polygon alas

Plumbaginales Hypothesis

My study tests the hypothesis that Cactaceae is monophyletic and

should occupy its own distinct clade within the order Caryophyllales. To test

this hypothesis, I used the cladistic technique of outgroup comparisons of rbcL

sequences of several genera of Caryophyllales with rbcL sequences of cacti

(Table 1). Since geneologic reconstructions are based on the premise that

species give rise to daughter species via speciation to produce phylogenies that

are natural (Wiley et al. 1991), then Cactaceae should be displayed as a monophyletic clade.

8 Materials and Methods

RbcL gene sequence data for all outgroup species and two ingroup species, (Pereskia aculeata and truncata) (Table 1) representing fifteen families from Caryophyllales, ,

Plumbaginales and Polygonales were downloaded from GenBank at the

National Institutes of Health (http://www.ncbi.nlm.nih.gov/ / taxonomyhome.html). Sequence data for the remaining four ingroup species were generated by Dougherty (1996).

The sequence data were entered into the management computer program, DNAStar, for spatial alignment. Aligned sequences were divided into the ingroup and outgroup (Table 1) and analyzed by PAUP 3.1. In the analysis, 1611 of 1992 characters were excluded as uninformative. Branch and bound options were tried, but they ran for over 12 hours and still had not found the first tree. The remaining 381 characters were used in a heuristic search to determine parsimony. The tree bisection- reconnection (TBR) branch swapping algorithm was used to improve the accuracy of the trees produced by the heuristic search. The resulting optimal trees were combined into a strict consensus tree (Figure 2) and re-analyzed with MacClade 3.06 to resolve polytomies.

9 Results

The length of the strict consensus tree is 994 steps out of a maximum of

1982 steps and a minimum 515 steps. The Consistency Index is 0.52; the

Retention Index is 0.67 and the Rescaled Consistency Index is 0.35.

Three polytomies occur in the consensus tree (Figure 2). The cactus group was unresolved between the Cactaceae and Portulacaceae. The next polytomy is between the Amaranthaceae and Chenopodiaceae;

Caryophyllaceae; Phaulothamnus spinescens (Acatocarpacea) ; and the species of the orders Nepenthales, Plumbaginales and Polygonales. The final polytomy is within the Caryophyllaceae species. MacClade 3.06 resolved the polytomies into four clades:

1. Cactaceae and Portulacaceae 2. Nepenthales, Plumbaginales, and Polygonales 3. Caryophyllaceae 4. Amaranthaceae and Chenopodiaceae Phaulothamnus spinescens (Acatocarpaceae) aligns with

Caryophyllaceae under soft polytomy resolution (Figure 3) or the

Amaranthaceae, Chenopodiaceae families under hard polytomy resolution

(Figure 4). Species ofNyctaginaceae, Phytolacaceae, Aizoaceae, and

Molluginaceae are fully resolved into a fifth clade. Stegnosperma halimifolium

10 is separated from the other Phytolacaceae species and

(Basellaceae) is the basal taxon of the outgroup species.

11 Figure 2. Strict Consensus of 12 Equally Parsimonious Trees generated with PAUP 3.

12 Alluadia procera (Didiereaceae) Amaranthus hypochondriacus (Amaranthaceae) Amaranthus tricolor (Amaranthaceae) petula (Chenopodiaceae) (Chenopodiaceae) Sinacea oleraceae (Chenopodiaceae) Arenaria drummondii (Caryophyllaceae) (Caryophyllaceae) Dianthus caryophyllus (Caryophyllaceae) Silene gallica (Caryophyllaceae) Dartingtonia califomica (Sarraceniaceae) Heliamphora nutans (Sarraceniaceae) flava (Sarraceniaceae) Plumbago capensis (Plumbaginaceae) Rheum x cultorum (Polygonaceae) Phaulothamnus spinescens (Achatocarpaceae) Stegnosperma halimifolium (Phytolaccaceae) Bougainvillea glabra (Nyctaginaceae) Mirabilis jalapa (Nyctaginaceae) ·Gisekia phamacioides (Phytolaccaceae) (Phytolaccaceae) (Phytolaccaceae) Lithops sp. (Aizoaceae) Mesembryanthemum crystallinum (Aizoaceae) Trianthema portulacastrum (Aizoaceae) (Molluginaceae) Basella alba (Basellaceae) Cereus pentagonus (Cactaceae) Schlumbergera truncata (Cactaceae) Pereskia aculeata (Cactaceae) Opuntia corallicola (Cactaceae) Opuntia spinosissima (Cactaceae) Opuntia spinosissima (Cactaceae) (Portulacaceae)

13 Figure 3. MacCiade 3.06 Soft Polytomy Resolution of Strict Consensus Tree

14 Alluadia procera (Didiereaceae) Portulaca grandiflora (Portulacaceae) Cereus pentagonus (Cactaceae) Schlumberger truncata (Cactaceae) Pereskia aculeata (Cactaceae) Opuntia corallicola (Cactaceae) Opuntia spinosissima (Cactaceae) Opuntia spinosissima (Cactaceae) Arenaria drummondii (Caryophyllaceae) Cerastium glomeratom (Caryophyllaceae) Dianthus caryophyllus (Caryophyllaceae) Silene gallica (Caryophyllaceae) Amaranthus hypochondriacus (Amaranthaceae) Amaranthus tricolor (Amaranthaceae) Atriplex petula (Chenopodiaceae) Atriplex rosea (Chenopodiaceae) Spinacea oleracea (Chenopodiaceae) Phaulothamnos spinescens (Achatocarpaceae) Darlingtonia califomica (Sarraceniaceae) Heliamphora nutans (Sarraceniaceae) Sarracenia flava (Sarraceniaceae) Plumbago capensis (Plumbaginaceae) Rhuem x cultorum (Polygonaceae) Stegnosperma halimifolium (Phytolacaceae) Bougainvillea glabra (Nyctaginaceae) Mirabilis jalapa (Nytaginaceae) Gisekia pharnacioides (Phytolaccaceae) Rivina humilis (Phytolaccaceae) Phytolacca americana (Phytolaccaceae) Lithops sp. (Aizoaceae) esembryanthemum crystallinum (Aizoaceae) Trianthema portulacastrum (Aizoaceae) ollugo verticillata (Molluginaceae) Basella alba (Basellaceae)

15 Figure 4. MacCiade 3.06 Hard Polytomy Resolution of Strict Consensus Tree

16 Alluadia procera (Didiereaceae) Amaranthus hypochondriacus (Amaranthaceae) Amaranthus tricolor (Amaranthaceae) Atriplex petula (Chenopodiaceae) Atriplex rosea (Chenopodiaceae) Sinacea oleraceae (Chenopodiaceae) Darlingtonia califomica (Sarraceniaceae) Heliamphora nutans (Sarraceniaceae) Sarracenia flava (Sarraceniaceae) Plumbago capensis (Plumbaginaceae) Rheum x cultorum (Polygonaceae) Phaulothamnus spinescens (Achatocarpaceae) Arenaria drummondii (Caryophyllaceae) Silene gallica (Caryophyllaceae) Cerastium glomeratum (Caryophyllaceae) Dianthus caryophyllus (Caryophyllaceae) Stegnosperma halimifolium (Phytolaccaceae) Bougainvillea glabra (Nyctaginaceae) Mirabilis jalapa (Nyctaginaceae) Gisekia phamacioides (Phytolaccaceae) Rivina humilis' (Phytolaccaceae) Phytolacca americana (Phytolaccaceae) Lithops sp. (Aizoaceae) Mesembryanthemum crystallinum (Aizoaceae) Trianthema portulacastrum (Aizoaceae) Mollugo verticillata (Molluginaceae) Basella alba (Basellaceae) Cereus pentagonus (Cactaceae) Schlumbergera truncata (Cactaceae) Pereskia aculeata (Cactaceae) Opuntia corallicola (Cactaceae) Opuntia spinosissima (Cactaceae) Opuntia spinosissima (Cactaceae) Portulaca grandiflora (Portulacaceae)

17 Discussion

The heuristic search option with TBR branch swapping was used due to the large number of taxa and characters (base pairs) used in the study.

Neither the exhaustive nor the branch and bound search methods would have been feasible. The strict consensus tree (Figure 2) is a combination of 12 equally parsimonious trees produced by the heuristic search.

The polytomies of the consensus tree (Figure 2) arise from a conservative algorithm that demands a polytomous group whenever there is disagreement in the placement of taxa among rival trees (Swofford and Begle

1993). For example, if eleven of the twelve trees agree on the resolution of a group but the twelfth tree places one taxon differently then the entire group is presented as a polytomy (Swofford and Begle 1993). Less stringent consensus techniques eliminate this disadvantage but are more difficult to interpret

(Swofford and Begle 1993).

Polytomies were resolved with MacClade 3.06: 1. soft resolution in which characters are resolved in the most favorable way although the total tree length may be smaller than what is actually possible; 2. hard resolution using multiple speciation events where each branch in the polytomy is assumed to have acquired the ancestral character independently of the other branches

(Madison and Madison 1992).

18 Ingroup monophyly is inferred from resolutions of outgroup taxa of

known relationships (Maddison et al. 1984). The outgroup representatives

align in patterns mostly congruent with previous studies. The clade formed by

the Nyctaginaceae and Phytolaccaceae species is supported by most authors

(Rettig et al., 1992). Aizoaceae members grouped with the species of

Nyctaginaceae and Phytolacaceae does not agree with Rodman's (1984)

hypothesis that the Aizoaceae is a sister group to Cactaceae, but is consistent

with previous results of Rettig et al. (1992); Downie and Palmer (1994); Bayer

et al. (1996); Downie et al., (1997); and Hershkovitz and Zimmer (1997).

Separation of Stegnosperma halimifolium from the other species of

Phytolacaceae is in agreement with other studies. This separation suggests that the Phytolacaceae may be polyphyletic (Bedell1980). Phytolaccaceae is also challenged as the basal family to nine of the families in the order

(Cronquist 1988). Figures 2 and 3 show Basella alba (Basellaceae) basal to the other outgroup species.

The basal position of Basella alba is not supported by other studies nor is its wide separation from Alluadia procera (Didiereaceae). Other studies nest

Basella alba with Portulaca and Alluadia species though separated from

Alluadia species by the Portulacaceous taxa (Rettig et al. 1992; Hershkovitz and Zimmer 1997).

The central positions of the Moluginaceae and the Caryophyllaceae contradict Cronquist's 1981 arrangement (Figure 1) but agree with more recent arrangements (Rettig et al. 1992; Hershkovitz et al. 1997; Downey and

Palmer 1994). Downy and Palmer (1994) point out that these central

19 positions indicate that the anthocyanin production seen in both families could be a reversal from pigment production (Downey et al. 1994).

The placement of Phaulothamnus spinescens (Acatocarpaceae) is uncertain based on the rbcL data. The species aligns with Caryophyllaceae in the hard polytomy resolution, but in the soft resolution it aligns with the

Amaranthaceae and Chenopodiaceae. Although this arrangement contradicts

Cronquist's 1981 arrangement (Figure 2) that Achatocarpaceae is derived from Phytolaccaceae, the equivocal placement in this study is possibly due to one or more uncertainties in the molecular character states; resulting in equal parsimony for either alignment.

The Amaranthaceae, Chenopodiaceae clade and its placement is in accordance with traditional taxonomic arrangements (Downey and Palmer

1994). The clade formed by the Sarraceniaceae, Plumbaginaceae and

Polygonaceae species is expected as they represent the subclass Dilleniidae and the orders Plumbaginales and Polygonales respectively and are removed relatively far taxonomically from the Caryophylalles species (Cronquist, 1988).

The taxonomic distance is not reflected, however, by the central placement of the clade in Figures 1 and 2 and is most likely due to equivocal character states.

The cactus ingroup clade, as inferred from resolution of the known outgroup relationships, supports the hypothesis that Cactaceae is monophyletic.

In the case of the Cactaceae-Portulacaceae relationship, the trees of

Figures 2 and 3 suggest that Portulacaceae is the sister group to Cactaceae.

20 While this arrangement is congruent with arrangements of other studies, it

should be noted that Portulaca grandiflora is the only representative of

Portulacaceae used in this study. Downey and Palmer (1994) included

Claytonia caroliniana and perfoliata together with Portulaca

oleracea in their examination of the Caryophyllales using structural

rearrangements of the cpDNA The two genera were well separated in the

bootstrap supported trees though nested with Didiereaceae, Basellaceae, and

Cactaceae (Downey and Palmer 1994). Rodman (1984) proposed that the

Portulacaceae is paraphyletic. Cladistics based on anatomical and molecular characters presents Cactaceae, Basellaceae, and Didieraceae nested among

Eastern American and Southern African portulacaceous species (Downey and

Palmer 1994; Hershkovitz and Zimmer 1997). The Eastern American and

Southern African Portulacaceae includes Portulaca but not Claytonia

(Hershkovitz and Zimmer 1997).

Of the Opuntia species studied, two samples were Opuntia spinosissima from Jamaica (Dougherty 1996). The third Opuntia specimen is from the

Florida Keys and is Opuntia corallicola (Austin and Pinkava 1991; Dougherty

1996). As expected the Jamaican show no branch distance between them. However, in all twelve tree arrangements, the two Opuntia spinosissima specimens are separated from Opuntia corallicola by branch lengths of either three or four steps. In eight of the 12 trees there are no steps separating Opuntia corralicola from the ancestral node. There is still controversy regarding the origins of these plants (Austin and Pinkava 1991;

Dougherty 1996 ) but, in terms of outgroup comparison within the Opuntia

21 lineage, this evidence strongly implies that Opuntia spinosissima and Opuntia corralicola have evolved from a common ancestor.

The evolution of the cacti as a New World group is only recently becoming understood. The outgroup analysis of my study shows that

Cactaceae clearly forms its own monophyletic clade. But, my study evokes other questions concerning the evolutionary pathways in the Cactaceae. Even though there is strong support for Portulacaceae as sister to Cactaceae the firm establishment of the sister to Cactaceae is dependent upon resolving the relationships within the Portulacaceae.

More work done on the Opuntioideae as well as the Pereskoideae will provide detail of one of the largest New World families of flowering plants. But, because Cactaceae contains approximately 1500 species in 100 genera and three subfamilies, the work needed to produce a clear phylogeny will require much time.

22 Literature Cited

1. C. Gibson, P. S. Nobel, The Cactus Primer. 1986 Harvard University

Press, Cambridge, Massachusetts, London, England.

2. A. Cronquist, The evolution and Classification of Flowering Plants.

1988 New York Botanical Garden, Bronx, N.Y.

3. C.J. Dougherty, Novel DNA Sequences of the Endangered Florida

Semaphore Cactus. Thesis 1996, Unpublished Florida Atlantic

University.

4. D. F. Austin and D. J. Pinkava, Preliminary Summary of the Taxonomic

Status of the Florida Semaphore Cactus. 1991, U. S. Fish and

Wildlife Service Office of endangered Species. Jacksonville, FL

5. D. L. Swofford and D.P. Begle, PAUP: Phylogenetic Analysis Using

Parsimony. 1993, illinois Natural History Survey: Champaign, IL.

6. E. 0. Wiley, D. Siegel-Causey, D. R. Brooks, V. A. Funk, The Compleat

Cladist A Primer of Phylogenetic Procedures. 1994 The University

of Kansas Museum of Natural History Special Publication,

Lawrence, Kansas.

7. H. G. Bedell, A taxonomic and morphological re-evaluation of

tegnospermaceae (Caryophyllales). Systematic Botany, 5(4) 1980,

p. 419-431

23 8. J. C. Avise, Molecular Markers, Natural History and Evolution. 1994

Chapman Hall, New York-London,

9. J.E. Rodman, A taxonomic analysis and revised classification of

Centrospermae. Systematic Botany, 9(3) 1984, p. 297-323.

10. J. H. Rettig, H. D. Wilson, J. R. Manhart, Phylogeny of the

Caryophyllales -gene sequence data. Taxon, 411992 p. 201-209

11. M.A. Hershkovitz, E. A. Zimmer, On the evolutionary origins of the

cacti. Taxon, 46 1997, p. 217-232

12. S. R. Downey, J.D. Palmer, A chloroplast DNA phylogeny of the

Caryophyllales based on structural and inverted repeat restriction

site variation. Systematic Botany, 19(2) 1994, p. 236-252.

13. S. R. Downey, D. S. Katz-Downie, K-J. Cho, Relationships in the

Caryophyllales as suggested by Phylogenetic analyses of partial

chloroplast DNA ORF2280. American Journal of Botany, 84(2)

1997, p. 253-257.

14. W. P. Maddison and D. R. Maddison, MacClade Version 3.06 Analysis of

Phylogeny and Character Evolution. 1992, Sinauer Associates:

Sunderland, MA.

15. W. P. Maddison, M. J. Donoghue, D. R. Maddison, Outgroup analysis and

parsimony. Systematic Zoology, 33 1984, p. 83-103

24