Please cite this document as: Austin, D. F. 1998. Parallel and Convergent Evolution in the Convolvulaceae. Pp. 201-234, In: Mathews, P. and M. Sivadasan (eds.). Diversity and Taxonomy of Tropical Flowering Plants, Mentor Books, Calicut, India.

Parallel and Convergent Evolution in the Convolvulaceae

Daniel F. Austin

Current address: Center for Sonoran Desert Research, Arizona-Sonora Desert Museum, 2021 N. Kinney Road, Tucson, AZ 85743, U.S.A.

Abstract
Parallelism is defined in this study as homologous traits within a family. Convergence occurs when different families have the same characteristics. To study the influence of these phenomena on phylogeny, an analysis was made of the Convolvulaceae using all 55 genera, plus major subdivisions of Ipomoea and Merremia. Traits were used for life form, longevity, roots, stems, leaves, inflorescences, flowers, pollen, fruits, seeds, embryos, cotyledons and chromosome numbers. Of 128 characteristics, 104 (80.7%) show parallelisms. Of these 104 parallelisms, 61 (47.7%) are also convergences with one or more outgroups. Three stages in the plant life-cycle are identified as driving parallel traits: vegetative, reproductive and dispersal. Reproduction is most important, selecting 66 traits; the other two are equally significant, driving 27 (environment) and 28 (dispersal) traits. Forces driving the remaining seven of the 128 traits are unknown. Current literature provides a theoretical and experimental context for the selective forces on the individual traits.


Modern understanding of convergent and parallel evolution began with the poet-philosopher Johann Wolfgang von Goethe and the biologist Etienne Geoffroy Saint-Hilaire between 1796 and 1818 (Panchen 1992). Today, the concepts are well-founded and confusion stems from a misinterpretation of structures, not from the distinction between homologies and analogies. Convergence is morphological similarity (analogy) in distantly related organisms (Mayr 1969; Mayr and Ashlock 1991). Parallelism is the independent acquisition of similar (homologous) characters in related evolutionary lines (Mayr 1969; Panchen 1992).

Phylogenetic computer analysis tests subjectively created traditional taxa (cf., Judd et al. 1994 and Brummitt 1996 for different views). My study uses this method to examine parallelism of traits within the Convolvulaceae, and trait convergence with related families.

Materials & Methods
Convergence is defined here as the acquisition of morphologically similar traits between families; parallel evolution is an occurrence of the same derived trait in different genera or infrageneric taxa within a family. Although this is an artificial separation (Panchen 1992), it is a functional approach. A data matrix of 128 characters was constructed for all 55 genera and many infrageneric taxa (Matrix ). Morphological traits were determined by examination of living and herbarium specimens, and from the literature (Table 1). In some African and Asian taxa specimens were not available, and the literature is provisionally accepted. Although in most cases traits are not variable, there are cases where, within one genus, they differ from one species to the other. Some examples are known where there is infraspecific variation. In these cases the traits have been coded with multiple states. All traits are unordered and equally weighed.

Data were analyzed with MacClade (Maddison & Maddison 1992) and PAUP (Swofford & Begle 1993). Due to the large database, it was not possible to use the branch-and-bound option of PAUP. Therefore, the heuristic analysis may not have found the shortest trees. Because the data were analyzed several dozen times over three years, the consensus tree presented is at least near the shortest for the data. No changes in the 100% clades occurred whether generated from 2600 trees (24 hrs) or 15467 (56.5 hrs), both on 32 MB RAM Macintosh StarMax 4000/200. Apparently the large number of trees is largely, or perhaps completely, due to the non-resolution of a few taxa. Therefore, these few taxa create an almost exponential number of trees.

Genera follow Brummitt (1992), which more accurately presents modern understanding of the family than Wielgorskaya (1995). Subdivisions of Ipomoea follow Verdcourt (1963) and Austin & Huaman (1996). Infrageneric taxa of Merremia follow Ooststroom (1953), except that Xenostegia has been segregated as have the anomalous M. sibirica (L.) Hall. f., M. vitifolia (N. Burman) Hall. f. allies, and the M. tuberosa (L.) Rendle allies.

Six outgroups were used to polarize traits and examine trends; these include all families that have historically been considered related to the Convolvulaceae (Cronquist 1981; Takhtajan 1986). Although Cronquist placed Cuscuta in its own family, he concluded that the genus is most nearly allied with Convolvulaceae.

Results and Discussion
A. Phyletic relations. The heuristic option of PAUP had found 15467 equally parsimonious trees after running 56.5 hours. With six outgroups consensus trees were 1288 steps long and had a consistency index of 0.5. Phacelia (Hydrophylllaceae) was consistently placed as the sister to Convolvulaceae, differing from traditional concepts (Cronquist 1981; Takhtajan 1986). With only Phacelia in the outgroup the tree was 1183 steps long, with a consistency index of 0.52 (Figures). Although this tree is a preliminary hypothesis on how the taxa are related, it will serve as a beginning point from which to explore parallelisms and convergences.

B. Evolutionary Trends. There are comparatively few solutions to plant survival in different environments, that have variable moisture regimes, insolation, animals. Plants have used many of these solutions repeatedly. Life form (tree, shrub, vine, herb, epiphyte), root type (storage vs. fibrous), indument (absent, simple, compound), leaf venation (pinnate, palmate) are common themes selected by the physical environment. The biotic environment directs how flowers are structured and colored through pollinators. More variability is found in these traits because of the comparatively large number of pollinators. Both the physical and biotic environments direct fruit and seed types as dispersal propagules. Each of these selective suites is constrained by the selective pressures and genetic load of the individual lineages.

Therefore, selective forces fall into three categories (environmental, pollination & dispersal), with a residual that remains unknown. The following synopsis offers comments on the parallelisms and convergences found within the Convolvulaceae. Traits follow the sequence in Table 1.

[1] Taproots. Ancestral: fibrous; Trends: parallelism; States & times Evolved: tuberous =>4. Selection: Environmental. Tuberous roots provide water & food storage (Waisel et al. 1996).

[2] Rhizomes. Ancestral: absent; Trends: autapomorphy in Convolvulus. Selection: Environmental. Associated with polyploidy; a survival mechanism (Waisel et al. 1996).

[3] Lateral storage root. Ancestral: no; Trends: autapomorphy in I. (Batatas). Selection: Environmental. Specialization of taproot lineage for storage (Waisel et al. 1996).

[4] Chlorophyll. Ancestral: present; Trends: autapomorphy in Cuscuta; Selection: Environmental. Associated with parasitism (Moreno et al. 1996).

[5] Parasitic. Ancestral: no; Trends: autapomorphy in Cuscuta. Selection: Environmental. Assures a food and water supply (Moreno et al. 1996).

[6] Stolons. Ancestral: absent; Trends: parallelism; States & Times Evolved: present =>5, Selection: Environmental. Associated with seasonally xeric sites or shifting substrates (Mosbrugger & Roth 1996).

[7] Stems. Ancestral: herbaceous; Trends: parallelism & convergence; States & Times Evolved: woody =>1. Selection: Environmental. Support & transport of water (Carlquist & Hanson 1991; McDonald 1992; Mosbrugger & Roth 1996). Catalpa & Solanum have converged to woody stems. Reversed to herbaceous 9 times.

[8] Longevity. Ancestral: perennial; Trends: parallelism & convergence; States & Times Evolved: annual =>13. Selection: Environmental. Annuals are often in unpredictable climates (Fox 1990, 1992). All but Catalpa & Solanum are annual.

[9] Erect. Ancestral: no; Trends: parallelism & convergence; States & Times Evolved: yes =>13. Selection: Environmental. Apparently related to extreme environments, i.e., deserts & wetlands (Auld & Morrison 1992; Mosbrugger & Roth 1996). All outgroups have erect species.

[10] Prostrate. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>15. Selection: Environmental. Related to extreme environments (Auld & Morrison 1992; Mosbrugger & Roth 1996).

[11] Stems aculeate. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>3. Selection: Environmental. Protection from herbivores?

[12] Stellate trichomes. Ancestral: absent; Trends: parallelism & convergence; States & Times Evolved: present =>7. Selection: Environmental. Controls light (including UV), heat, and moisture (Karabourniotis & Fasseas 1996). Solanum has converged.

[13] Glandular trichomes. Ancestral: no; Trends: parallelism & convergence; States & Times Evolved: yes =>5. Selection: Environmental. Deter foraging insects; also for water conservation (Goertzen & Small 1993; Neal et al. 1990, Weiglin & Winter 1988). In all outgroups except Catalpa.

[14] Leaf arrangement. Ancestral: alternate; Trends: autapomorphy in Cuscuta; States & Times Evolved: opposite =>2. Selection: Environmental. Leaves are opposite in Catalpa and Penstemon; absent in Cuscuta.

[15] Leaf size. Ancestral: normal; Trends: autapomorphy in Cuscuta. Selection: Environmental. Chlorophyll loss correlates with parasitism in many kinds of plants (Brown & Lawton 1991; Moreno et al. 1996).

[16] Leave circular or reniform. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>10. Selection: Environmental. Shape & dissection decrease heat load, and herbivory pressure (Brown & Lawton 1991; Mackay & Jones 1989).

[17] Leaf base cordate. Ancestral: equivocal; Trends: parallelism & convergence; States & Times Evolved: yes =>3. Selection: Environmental. Uncertain (Brown & Lawton 1991; Jones 1995). All outgroups except Phlox.

[18] Leaf base cuneate. Ancestral: no; Trends: parallelism & convergence; States & Times Evolved: yes =>17. Selection: Environmental. Uncertain (Brown & Lawton 1991; Jones 1995). Also in Phlox.

[19] Leaves absent. Ancestral: no; Trends: autapomorphy in Cuscuta. Selection: Environmental. Linked with parasitism (Moreno et al. 1996).

[20] Leaf base hastate. Ancestral: no; Trends: parallelism & convergence; States & Times Evolved: yes =>8. Selection: Environmental. Uncertain (Brown & Lawton 1991; Jones 1995). Converged with Solanum.

[21] Leaf lobing. Ancestral: none; Trends: parallelism & convergence; States & Times Evolved: pinnate =>5;palmate =>11. Selection: Environmental. Heat-load reduction; predator avoidance (Brown & Lawton 1991; Jones 1995). Convergence with Phacelia, Phlox & Solanum.

[22] Leaf venation. Ancestral: pinnate; Trends: parallelism; States & Times Evolved: palmate =>10. Selection: Environmental. Surface water control (Roth et al. 1995; Neugebauer et al. 1995),

[23] Cymes. Ancestral: equivocal; Trends: parallelism & convergence; States & Times Evolved: monochasial =>17. Selection: Pollination: Pollinators are selecting structure (Cowen & Shmida 1993; Galen 1989; Waser et al. 1996). Monochasia occur in Solanum.

[24] Inflorescence solitary. Ancestral: no; Trends: parallelism & convergence; States & Times Evolved: yes =>25. Selection: Pollination: Showy flowers associated with pollinators; inconspicuous with autogamy (Johnston 1991; Lloyd and Barrett 1996; Real 1983; Schoen & Dubuc 1990). Also solitary in Solanum.

[25] Inflorescence capitate. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>5. Selection: Pollination: Protection from flower robbers (Real 1983; Schoen & Dubuc 1990).

[26] Inflorescence umbellate. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>3. Selection: Pollination: Clustering enhances pollination (Lloyd and Barrett 1996; Real 1983; Schoen & Dubuc 1990).

[27] Inflorescence paniculate. Ancestral: no; Trends: parallelism & convergence; States & Times Evolved: yes => 6. Selection: Pollination: Clustering enhances pollination (Lloyd and Barrett 1996; Real 1983; Schoen & Dubuc 1990). Shared with Penstemon.

[28] Inflorescence fascicled. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>86. Selection: Pollination: Clustering enhances pollination (Lloyd and Barrett 1996; Real 1983; Schoen & Dubuc 1990).

[29] Bract type. Ancestral: scale-like; Trends: parallelism & convergence; States & Times Evolved: leaf-like =>126. Selection: Pollination: Floral protection (Bentley & Elias 1983; Real 1983). Phlox has converged.

[30] Bract enlargement. Ancestral: parallelism; Trends: parallelism; States & Times Evolved: accrescent =>26. Selection: Pollination: Floral protection (Bentley & Elias 1983; Real 1983).

[31] Bracteole location. Ancestral: equivocal; Trends: parallelism; States & Times Evolved: equivocal =>6. Selection: Pollination: Uncertain, but cf. Singh & Urrea 1996.

[32] Involucre. Ancestral: absent; Trends: parallelism; States & Times Evolved: present =>4. Selection: Pollination: Protection from flower robbers (Real 1983).

[33] Involucre type. Ancestral: neither; Trends: parallelism; States & Times Evolved: separate =>3; fused =>1. Selection: Pollination: Possibly fused bracts provide better floral protection (Bentley & Elias 1983; Real 1983).

[34] Flower sex. Ancestral: bisexual; Trends: unisexual synapomorphy> Cladostigma & Hildebrandtia. Selection: Pollination: Outcrossing & other benefits (Karoly 1994; Lloyd and Barrett 1996; Louda & Potvin 1995; Sakai et al. 1995; Thompson & Burnet 1990; Renner & Ricklefs 1995).

[35] Outer sepal tip. Ancestral: acute to acuminate; Trends: parallelism & convergence; States & Times Evolved: round =>5. Selection: Pollination: Ovary protection (Bentley & Elias 1983; Real 1983). Phlox converged to caudate sepals in Ipomoea sect. Calonyction.

[36] Sepal texture. Ancestral: membranous; Trends: parallelism & convergence; States & Times Evolved: herbaceous =>4; membranaceous =>5. Selection: Pollination: Corolla & ovary protection (Bentley & Elias 1983; McDonald 1991; Sood & Pathak 1990); possibly protection from Megacerus FŒhr. beetles (Bruchidae) that lay their eggs inside sepals (Teran & Kingsolver 1977). Outgroups share all three states.

[37] Sepal margins. Ancestral: membranous; Trends: parallelism & convergence; States & Times Evolved: scarious =>2. Selection: Pollination: Ovary protection? Membranaceous, herbaceous and coriaceous sepals are all found in the outgroups.

[38] Flower sepal length. Ancestral: equal; Trends: parallelism & convergence; States & Times Evolved: unequal =>19. Selection: Pollination: Protection from biting insects (Bentley & Elias 1983). Unequal shared by Penstemon.

[39] Outer flower sepals. Ancestral: equal; Trends: parallelism & convergence; States & Times Evolved: longer =>17; shorter =>9. Selection: Pollination: Ovary protection?

[40] Number sepal veins. Ancestral: multiple veins; Trends: parallelism & convergence; States & Times Evolved: single =>3. Selection: Pollination: Uncertain. Shorter sepals are shared by Phlox.

[41] Sepal fusion. Ancestral: none; Trends: parallelism & convergence; States & Times Evolved: basal =>5. Selection: Pollination: Uncertain. Fused in all outgroups except Penstemon & Phacelia.

[42] Calyx size. Ancestral: normal; Trends: autapomorphy in Nephrophyllum, obsolete. Selection: Pollination: Possibly associated with autogamy (Real 1983; Sebsebe & Austin 1995).

[43] Outer 2 sepals. Ancestral: not enlarged; Trends: parallelism; States & Times Evolved: unequal =>14. Selection: Pollination: Flower & ovary protection (Bentley & Elias 1983; Real 1983).

[44] Pedicel+calyx adnation. Ancestral: no; Trends: autapomorphy in Hildebrandtia. Selection: Pollination: Uncertain (Sebsebe & Austin 1996).

[45] Calyx corolla ratio. Ancestral: short calyx; Trends: parallelism; States & Times Evolved: long =>4. Selection: Pollination: Protection against biting animals (Bentley & Elias 1983; Real 1983).

[46] Bud aestivation. Ancestral: valvate-induplicate; Trends: parallelism & convergence; States & Times Evolved: plicate =>10; contortiplicate =>12. Selection: Pollination: Possibly a function of corolla size and/or shape changes. Valvate-induplicate buds are shared by Solanum.

[47] Interplical pubescence. Ancestral: pubescent; Trends: parallelism & convergence; States & Times Evolved: glabrous =>12. Selection: Pollination: Pubescence may afford some protection from herbivores. Pubescent in Phacelia.

[48] Interplicae hirsute. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>7. Selection: Pollination: Pubescence may afford some protection.

[49] Interplical veins. Ancestral: equivocal; Trends: parallelism; States & Times Evolved: three =>3. Selection: Pollination: Uncertain.

[50] Corolla size. Ancestral: <1 cm; Trends: parallelism & convergence; States & Times Evolved: >3 cm =>4. Selection: Pollination: Adaptation to different size pollinators (Bentley & Elias 1983; Campbell et al. 1991; Conner & Sterling 1995, 1996; Galen 1989; Real 1983; Schemske & Horvitz 1989; Waser et al. 1996). Catalpa & Penstemon share large size.

[51] Corolla colors. Ancestral: white-yellow; Trends: parallelism & convergence; States & Times Evolved: blue-red =>11. Selection: Pollination: Associated with pollinator color vision & color preference (Barth 1991; Faegri & van der Pijl 1966; Lloyd and Barrett 1996; Waser et al. 1996; White et al. 1994; Willmott & B|rquez 1996; Wilson & Stine 1996). Catalpa has white- yellow corollas, other outgroups blue-red.

[52] Corolla pattern. Ancestral: uniform; Trends: parallelism & convergence; States & Times Evolved: light+dark =>13; dark+light =>10. Selection: Pollination: Nectar guides (Barth 1991; Faegri & van der Pijl 1966; Lloyd and Barrett 1996; Real 1983). Dark limb+light throat is shared by Cynoglossum and Phlox.

[53] Corolla shape. Ancestral: bell; Trends: parallelism & convergence; States & Times Evolved: salver =>14; rotate =>2. Selection: Pollination: Associated with pollination type (Barth, 1991; Bentley & Elias 1983; Cresswell & Galen 1991; Galen 1996; Real 1983; Smith et al. 1996). Bell, funnel and salver-shaped in outgroups.

[54] Corolla symmetry. Ancestral: radial; Trends: convergence; States & Times Evolved: zygomorphic =>1. Selection: Pollination: Related to pollinators (Barth 1991; Bentley & Elias 1983; Cresswell & Galen 1991; Smith et al. 1996). Three times in the outgroups.

[55] Lobing of corolla. Ancestral: deep (350%); Trends: parallelism & convergence; States & Times Evolved: shallow to deep =>8. Selection: Pollination: Associated with pollinators (Bentley & Elias 1983; Herrera 1993; Real 1983; Smith et al. 1996). Both states in outgroups.

[56] Corolla lobes. Ancestral: entire; Trends: parallelism & convergence; States & Times Evolved: bifid =>3. Selection: Pollination: Associated with pollinators (Cresswell & Galen 1991; Herrera 1993; Smith et al. 1996). Also occurs in Solanum & Phlox.

[57] Disc in flower. Ancestral: present; Trends: parallelism; States & Times Evolved: absent =>6. Selection: Pollination: Some associated with autogamy (pers. obs.).

[58] "Gynobasic". Ancestral: no; Trends: convergence; States & Times Evolved: yes =>1, Pollination: Uncertain. Pseudo-gynobasic in Dichondra. True gynobasic in Cynoglossum.

[59] Gynophore. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>3. Selection: Pollination: Uncertain.

[60] Style. Ancestral: present; Trends: autapomorphy in Erycibe. Selection: Pollination: Presumably associated with pollinators (Bentley & Elias 1983; Real 1983).

[61] Styles two. Ancestral: yes; Trends: parallelism & convergence; States & Times Evolved: reversal to yes =>3. Selection: Pollination: Anther mimicry (Barth 1991; Bentley & Elias 1983; Lloyd and Barrett 1996; Real 1983). Also in Phacelia.

[62] 2 style arms. Ancestral: unequal; Trends: parallelism & convergence; States & Times Evolved: equal =>5. Selection: Pollination: Anther mimicry (Barth 1991; Bentley & Elias 1983; Lloyd and Barrett 1996). Also in Phacelia.

[63] Stylar fusion. Ancestral: free to partly fused; Trends: parallelism & convergence; States & Times Evolved: complete =>1; free =>3. Selection: Pollination: Presumably associated with pollinators (Barth 1991; Bentley & Elias 1983; Real 1983). Free styles in Phacelia.

[64] Style caducous. Ancestral: yes; Trends: autapomorphy in Paralepistemon. Selection: Pollination: Presumably associated with pollinators (Barth 1991; Bentley & Elias 1983).

[65] Stigma position. Ancestral: included; Trends: parallelism & convergence; States & Times Evolved: excluded =>14. Selection: Pollination: Related to pollinators, often moths and birds (Bentley & Elias 1983; Campbell et al. 1994; Conner & Sterling 1995; Johnston 1991). Shared by Penstemon, Phacelia and Solanum.

[66] Stigma shape. Ancestral: globose; Trends: parallelism & convergence; States & Times Evolved: elongate =>9; lobulate =>2. Selection: Pollination: Presumably related to pollinators (Bentley & Elias 1983). Elongate in 4 outgroups.

[67] Stigma lobes. Ancestral: two; Trends: parallelism & convergence; States & Times Evolved: lobulate =>2; four =>3. Selection: Pollination: Presumably associated with pollinators (Bentley & Elias 1983; Real 1983). Three lobes in Phlox.

[68] Pistil pubescence. Ancestral: glabrous; Trends: parallelism & convergence; States & Times Evolved: multicellular =>14. Selection: Pollination: Presumably affords protection to pistil (Bentley & Elias 1983); shared with Solanum.

[69] Placentation. Ancestral: basal; Trends: autapomorphies in Cynoglossum & Phacelia (cf. Govil 1972 for another view). Selection: Pollination: Reproductive efficiency (Lloyd & Barrett 1996). Converged with Solanum. Phacelia is parietal, Cynoglossum is pendulous.

[70] Number of ovules. Ancestral: four; Trends: parallelism & convergence; States & Times Evolved: two =>3; >six =>1. Selection: Pollination: Reproductive efficiency (Lloyd & Barrett 1996; Shaankar et al. 1990; Waser & Price 1991). More than six are shared by Humbertia and four of the outgroups.

[71] No. ovules per locule. Ancestral: two; Trends: parallelism; States & Times Evolved: one =>11. Selection: Pollination: Reproductive efficiency (Lloyd & Barrett 1996).

[72] Epipetalous stamens. Ancestral: no; Trends: autapomorphy in Solanum. Selection: Pollination: Uncertain. Only in outgroup.

[73] Filament insertion. Ancestral: near base; Trends: parallelism & convergence; States & Times Evolved: in tube =>9. Selection: Pollination: Associated with tongue length in pollinators (Bentley & Elias 1983; Conner & Sterling 1995; Real 1983). Also in 2 outgroups.

[74] Filament length. Ancestral: one; Trends: parallelism & convergence; States & Times Evolved: two =>18; three =>17. Selection: Pollination: Associated with pollinators (Lloyd & Barrett 1996). Two in Catalpa & Penstemon; three in Phlox.

[75] Filament base. Ancestral: dilated; Trends: parallelism & convergence; States & Times Evolved: straight =>16. Selection: Pollination: Associated with pollinators (Bentley & Elias 1983). In five of the outgroups.

[76] Filament base pubescent. Ancestral: pubescent; Trends: parallelism & convergence; States & Times Evolved: glabrous =>20. Selection: Pollination: Associated with autogamy; also bird and moth pollination (Bentley & Elias 1983).

[77] Corolla scales. Ancestral: absent; Trends: parallelism; States & Times Evolved: filamental =>3. Selection: Pollination: Presumably affords ovary protection (Bentley & Elias 1983; Real 1983).

[78] Staminode base. Ancestral: absent; Trends: convergence; States & Times Evolved: parallel =>1; dilate =>1. Selection: Pollination: Uncertain. Also in Catalpa.

[79] Anther shape. Ancestral: sagittate; Trends: parallelism & convergence; States & Times Evolved: reniform =>1; ovoid =>3. Selection: Pollination: Associated with pollinators (Bentley & Elias 1983). Ovoid in Cynoglossum and Phacelia.

[80] Anther dehiscence. Ancestral: straight; Trends: parallelism; States & Times Evolved: twisted =>4. Selection: Pollination: Presumably to increase surface area exposed to pollinators (Bentley & Elias 1983; Real 1983).

[81] Pollen presentation. Ancestral: equivocal; Trends: parallelism; States & Times Evolved: extrorse =>7; versatile =>6. Selection: Pollination: Associated with pollinator behavior (Bentley & Elias 1983; Real 1983).

[82] Pollen shape. Ancestral: prolate; Trends: parallelism & convergence; States & Times Evolved: oblate =>14; spheroidal =>8. Selection: Pollination: Uncertain (cf. Austin 1973b; Pedraza 1983). Spheroidal & prolate are in outgroups.

[83] Pollen size. Ancestral: small (20-40µ); Trends: parallelism; States & Times Evolved: medium =>7; large =>4. Selection: Pollination: Correlated with style length (Bentley & Elias 1983; Taylor & Levin 1974).

[84] Pollen colpae. Ancestral: 3-colpate; Trends: parallelism; States & Times Evolved: 12-15-rugate =>9; 5-6-colpate =>2. Selection: Pollination: Uncertain, but see Dajoz & Till-Bottraud 1992; Taylor & Levin 1974. Phacelia has 3-colpate and 5-6-colpate pollen.

[85] Pollen pores. Ancestral: colpate; Trends: parallelism; States & Times Evolved: porate =>4. Selection: Pollination: Uncertain, but see Dajoz & Till-Bottraud 1992; Taylor & Levin 1974.

[86] Exine pattern. Ancestral: scrobiculate; Trends: convergence; States & Times Evolved: reticulate =>1. Selection: Pollination: Uncertain, but shared with three of outgroups (Taylor & Levin 1974).

[87] Punctae. Ancestral: equivocal; Trends: parallelism; States & Times Evolved: yes =>4. Selection: Pollination: Uncertain (Taylor & Levin 1974).

[88] Echinate. Ancestral: no; Trends: synapomorphy> Argyreieae & Ipomoeeae. Selection: Pollination: Uncertain.

[89] Calyx accresccent in fruit. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>8. Selection: Dispersal: Wind and/or water dispersal (Staples 1987).

[90] Fruit shape. Ancestral: ovoid; Trends: parallelism & convergence; States & Times Evolved: globose =>14. Selection: Dispersal: Uncertain. Both states are in the outgroups.

[91] Fruiting sepals. Ancestral: surrounding; Trends: parallelism & convergence; States & Times Evolved: reflexed =>3. Selection: Dispersal: Maybe distribution of fruits; convergent with Phacelia.

[92] Fruit pedicel swollen. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>4. Selection: Dispersal: Uncertain.

[93] Fruit pedicel position. Ancestral: straight; Trends: parallelism, recurved =>11. Selection: Dispersal: Probably to spread seeds.

[94] Fruit dehiscence. Ancestral: capsular; Trends: parallelism & convergence; States & Times Evolved: tardy =>4. Selection: Dispersal: Probably wind and water dispersal. Tardily dehiscent fruits are in Cynoglossum & Solanum.

[95] Fruit dehiscence direction. Ancestral: longitudinal; Trends: parallelism & convergence; States & Times Evolved: circular =>2. Selection: Dispersal: Seed spreading; also in Cynoglossum.

[96] Fruit type. Ancestral: dry; Trends: parallelism & convergence; States & Times Evolved: fleshy =>2. Selection: Dispersal: Animal dispersal (Austin 1973a). Also fleshy in Solanum.

[97] Baccate type. Ancestral: neither; Trends: parallelism & convergence; States & Times Evolved: leathery to woody =>1; fleshy =>2. Selection: Dispersal: Animal dispersal. Cynoglossum and the Erycibeae have leathery to woody fruits. Fleshy in Solanum.

[98] Utricle. Ancestral: no; Trends: parallelism, yes =>. Selection: Dispersal: Associated with wind dispersal (Staples 1987).

[99] Loculicidal. Ancestral: yes; Trends: parallelism & convergence; States & Times Evolved: no =>2. Selection: Dispersal: Outgroups Cynoglossum and Solanum share this loss.

[100] Septicidal. Ancestral: no; Trends: convergence; States & Times Evolved: yes =>2. Selection: Dispersal: Only in Penstemon and Phacelia.

[101] Unopened fruit lobes. Ancestral: one; Trends: parallelism & convergence; States & Times Evolved: four =>2. Selection: Dispersal: Shared with Cynoglossum.

[102] Fruit locules. Ancestral: two; Trends: parallelism & convergence; States & Times Evolved: four =>7; one =>6. Selection: Dispersal: Uncertain. Outgroups share three (Phlox) and four (Cynoglossum) locules.

[103] No. seeds per fruit. Ancestral: one to four; Trends: parallelism; States & Times Evolved: one =>6; two =>1; >four =>1. Selection: Dispersal: Uncertain, but see Shaankar et al 1990.

[104] Fruit valves. Ancestral: equivocal; Trends: parallelism & convergence; States & Times Evolved: none =>6; two =>3. Selection: Dispersal: Ipomoea sect. Pharbitis has converged with Phlox for 3-valves.

[105] Fruit valves >4. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>2. Selection: Dispersal: Possibly more efficient seed spread.

[106] Pericarp. Ancestral: ligneous; Trends: parallelism & convergence; States & Times Evolved: chartaceous =>9. Selection: Dispersal: Perhaps wind and water dispersal. Also, in Cuscuta. Fleshy fruits shared with Solanum.

[107] Endocarp. Ancestral: absent; Trends: parallelism; States & Times Evolved: present =>3. Selection: Dispersal: Flotation in Iseia, Itzaea & Stictocardia.

[108] Endocarp textures. Ancestral: none; Trends: parallelism; States & Times Evolved: spongy =>3. Selection: Dispersal: Flotation (Austin & Sebsebe 1997).

[109] Endocarp valves. Ancestral: absent; Trends: autapomorphy in Stictocardia. Dispersal: Seed release (Gunn 1972).

[110] Perisperm. Ancestral: absent; Trends: parallelism; States & Times Evolved: present =>3. Selection: Dispersal: In Erycibeae for animal spread (Austin 1973a).

[111] Seed shape. Ancestral: ovoid; Trends: parallelism & convergence; States & Times Evolved: globose =>7. Selection: Dispersal: Microhabitat requirements for germination (Lungu and Culham 1996). Globose seeds are shared with Cynoglossum.

[112] Seed surface. Ancestral: equivocal; Trends: parallelism & convergence; States & Times Evolved: roughened =>6. Selection: Dispersal: Uncertain. Shared with Penstemon, Phacelia and Solanum.

[113] Seed winged. Ancestral: no; Trends: parallelism; States & Times Evolved: yes =>5. Selection: Dispersal: Possibly ontogenetic?

[114] Seed coat. Ancestral: ligneous; Trends: convergence; States & Times Evolved: chartaceous =>2. Selection: Dispersal: Animal dispersal in Erycibeae (Austin 1973a). Wind in Catalpa. Unknown in Phacelia.

[115] Seed pubescence. Ancestral: glabrous; Trends: parallelism; States & Times Evolved: puberulent => 12; woolly =>3. Selection: Dispersal: Wind and water dispersal.

[116] Seed pubescence location. Ancestral: throughout; Trends: parallelism; States & Times Evolved: marginal =>7. Selection: Dispersal: Wind and water dispersal.

[117] Hilum shape. Ancestral: Ipomoea-type; Trends: parallelism; States & Times Evolved: Convolvulus-type =>6. Selection: Unknown (cf. Gunn 1969).

[118] Endosperm. Ancestral: cartilaginous; Trends: convergence; States & Times Evolved: absent =>1. Selection: Unknown. Rapid germination & short life-span in Erycibeae & Catalpa. Oily in other outgroups.

[119] Cotyledon lobing. Ancestral: equivocal; Trends: parallelism & convergence; States & Times Evolved: deep =>6; unlobed =>6. Selection: Environmental. Presumably available light and moisture are involved. Unlobed and deeply lobed are in the outgroups.

[120] Cotyledon or lobule shape. Ancestral: ovate; Trends: parallelism & convergence; States & Times Evolved: linear-lanceolate =>5, absent =>1. Selection: Environmental. Uncertain. Solanum has both ovate & linear-lanceolate lobes.

[121] Hypocotyl length. Ancestral: long; Trends: parallelism; States & Times Evolved: short =>2. Selection: Environmental. Found in xeric or haline habitats.

[122] Embryo folds. Ancestral: folded-longitudinally; Trends: parallelism & convergence; States & Times Evolved: coiled =>2, straight =>2. Selection: Unknown. Coiled in Phlox and Solanum; straight in four outgroups.

[123] Embryo shape. Ancestral: linear; Trends: convergence; States & Times Evolved: linear =>1, Unknown. Linear in Solanum; ovate to elliptic in Catalpa.

[124] Cotyledon venation. Ancestral: pinnate; Trends: parallelism; States & Times Evolved: pinnate =>5; solitary =>1. Selection: Environmental. Uncertain.

[125] Basal sinus. Ancestral: absent; Trends: parallelism & convergence; States & Times Evolved: present =>1. Selection: Environmental. Uncertain. Reversed to absent 3 times. Absent in outgroups.

[126] Base chromosome Number. Ancestral: x=14; Trends: parallelism; States & Times Evolved: x=7 =>1; x=12 =>3; x=14 =>9; x=15 =>9. Selection: Unknown. Contingent fact of history? Phlox and Cuscuta have x=7; x=12 in Solanum and Cynoglossum is shared with Convolvulus, Calystegia and Evolvulus (Austin 1973a; Lewis 1980; Manitz 1983).

[127] Aneuploidy. Ancestral: absent; Trends: parallelism & convergence; States & Times Evolved: present =>9. Selection: Unknown. Also in Phlox.

[128] Polyploidy. Ancestral: absent; Trends: parallelism & convergence; States & Times Evolved: present =>6. Selection: Unknown. Associated with unstable environments (Lewis 1980). Also in Cynoglossum.

C. General Evolutionary trends. Convolvulaceous parallelisms combined with traits showing parallelisms and convergences represent 104 (80.7%) of 128 characteristics (Table 2). Parallelism occurs for 43 traits (33%); parallelism and convergence in 61 (47.7%). Convergence with outgroups developed in 8 characters (6.3%). Autapomorphies and synapomorphies evolved 16 (12.5%) times, i.e., not homoplasies.

Vegetative, reproductive, and dispersal stages in the plant life-cycle have selected parallel traits Table 2). These selective phases direct establishment, reproduction, and colonization, the most important events in the lives of the plants. The reproductive stage is the strongest, driving 66 characters. Less important forces are dispersal (28 traits) and environment (27 traits) that select fruit and vegetative characteristics respectively. The seven remaining traits are so incompletely known that they could not be assigned to either establishment, reproduction, or colonization.

Acknowledgments
The database was begun in 1993 while Sebsebe Demissew (Addis Abeba University, Ethiopia) was working with me on a Fulbright Fellowship. Traits were compiled and coded in collaboration with Sebsebe, George Staples (Bishop Museum, Honolulu, HI), Paul Wilkin (Royal Botanic Gardens, Kew), and Robert Johnson (National Herbarium, Brisbane, Australia). Colleagues at the British Museum of Natural History and the Royal Botanical Garden, Kew, Missouri Botanical Garden, St. Louis, the New York Botanical Garden, and Usha Sudhakar (FAU Library) aided with the literature. I thank Paul Wilkin, Sebsebe Demissew and George Staples for comments on a draft manuscript. Although we do not always agree on interpretations, our discussions are lively, constructive, and valuable to me. My wife Sandra also offered suggestions and ideas toward the final text. Publication was supported by the Florida Atlantic University Foundation.

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ARIZ Herbarium

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Created: 1 May 1999; Last updated: 6 Oct. 2001

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