Abstract
Portulaca is the only genus in Portulacaceae and includes ca. 115 species with worldwide distribution. 12 species (one naturalized) occur in Cuba. The taxonomic value of seeds characters for the circumscription of species, by comparing macro- and micromorphological characters, is analyzed. The seeds of Cuban purslanes do not present association patterns between types of undulations of the anticline walls. The relief of their periclinal walls allows the corroborate certain variation in the distribution range of some species. The delimitation of Portulaca species in Cuba using seeds characters, provided as an identification key and descriptions, confirms the taxonomic value of such characters and strengthens the circumscriptions supported by the rest of the plant structures. This is largely given by the standardization of macromorphological terms with a micromorphological basis, the color of the mature seeds and their dimensions.
References
<p>Amini, M., Sajedi, S. & Domina, G. (2017) First data on the taxonomic diversity of the <em>Portulaca oleracea</em> aggregate (Portulacaceae) in Iran. <em>Turkish Journal of Botany</em> 41: 535–541. http://dx.doi.org/10.3906/bot-1611-43</p>
<p>Barthlott, W. (1981) Epidermal seed surface characters of plants: systematic applicability and some evolutionary aspects. <em>Nordic Journal of Botany</em> 1: 345–355. https://doi.org/10.1111/j.1756-1051.1981.tb00704.x</p>
<p>Coelho, A.A.O.P. & Giulietti, A.M. (2010) O gênero <em>Portulaca</em> L. (Portulacaceae) no Brasil. <em>Acta Botanica Brasilica </em>24 (3): 655–670. https://doi.org/10.1590/S0102-33062010000300009</p>
<p>Dalavi, J.V., Chougule, R.N., Jadhav, V.D. & Yadav, S.R. (2019) Variation in Seed Micromorphology in Portulaca L. (Portulacaceae) in India. <em>Phytomorphology</em> 69 (1 & 2): 15–24.</p>
<p>Danin, A. & Anderson, L.C. (1986) Distribution of <em>Portulaca oleracea</em> L. (Portulacaceae) subspecies in Florida. <em>Sida</em> 11 (3): 318–324. [https://www.jstor.org/stable/23909826]</p>
<p>Danin, A. & Reyes-Betancort, J.A. (2006) The status of <em>Portulaca oleracea</em> L. in Tenerife, the Canary Islands. <em>Lagascalia</em> 26: 71–81.</p>
<p>Danin, A. & Raus, T. (2012) A key to 19 microspecies of the <em>Portulaca oleracea</em> aggregate. <em>In:</em> Timonin, A.K., Sukhorukov, A.P., Harper, G.H. & Nilova, M.V. (Eds.) <em>Caryophyllales: New insights into phylogeny, systematics, and morphological evolution of the order, Proceedings of the Symposium held on 24th–27th September 2012</em>. Lomonosov State University, Moscow, pp. 70–83.</p>
<p>Danin, A., Baker, I. & Baker, H.G. (1978) Cytogeography and taxonomy of the <em>Portulaca oleracea</em> L. polyploid complex. <em>Israel Journal of Botany</em> 27: 177–211.</p>
<p>Danin, A., Domina, G. & Raimondo, F.M. (2008) Microspecies of the <em>Portulaca oleracea</em> aggregate found on major Mediterranean islands (Sicily, Cyprus, Crete, Rhodes). <em>Flora Mediterranea </em>18: 89–107.</p>
<p>Danin, A., Buldrini, F., Bandini, M. & Bosi, G. (2014) The history of the <em>Portulaca oleracea</em> aggregate in the Emilia-Romagna Po Plain (Italy) from the Roman Age to the present. <em>Plant Biosystems</em> 148 (4): 622–634. http://dx.doi.org/10.1080/11263504.2013.788098</p>
<p>Danin, A., Buldrini, F., Bandini Mazzanti, M., Bosi, G., Caria, M.C., Dandria, D., Lanfranco, E., Mifsud, S. & Bagella, S. (2016) Diversification of <em>Portulaca oleracea</em> L. complex in the Italian peninsula and adjacent islands. <em>Botany Letters</em> 163: 261–272. https://doi.org/10.1080/23818107.2016.1200482</p>
<p>Denis, D. & Ramírez-Arrieta, V.M. (2020) Si una imagen vale más que mil palabras: ¿cuánto puede decir un gráfico de cajas? <em>Revista del Jardín Botánico Nacional</em> 41: 57–69.</p>
<p>Eggli, U. & Ford-Werntz, D. (2002) Portulacaceae. <em>In</em>: Eggli, U. & Ford-Werntz, D. (Eds.) <em>Illustrated Handbook of Succulent Plants-Dicotyledons</em>. Springer, New York, pp. 370–432. https://doi.org/10.1007/978-3-642-56316-4_48</p>
<p>El-Bakatoushi, R., Alframawy, A.M., Samer, M., El-Sadek, L. & Botros, W. (2013) Evolution of the <em>Portulaca</em> <em>oleracea</em> L. aggregate in Egypt on molecular and phenotypic levels revealed by morphology, inter-simple sequence repeat (ISSR) and 18S rDNA gene sequence markers. <em>Flora</em> 208: 464–477. https://doi.org/10.1016/j.flora.2013.07.008</p>
<p>García-Beltrán, J.A., Barrios, D., Toledo, S. & Testé, E. (2020) Distribución y conservación de <em>Portulaca</em> (Portulacaceae) en Cuba. <em>Botanical Sciences</em> 98 (3): 597–617. https://doi.org/10.17129/botsci.2545</p>
<p>García-Beltrán, J.A., Barrios, D. & Bécquer, E.R. (2021) Revisión taxonómica de Portulacaceae en Cuba. <em>Brittonia</em> 73 (3): 1–31. https://doi.org/10.1007/s12228-021-09653-0</p>
<p>Hernández-Ledesma, P., Berendsohn, W.G., Borsch, Th., Mering, S., Akhani, H., Arias, S., Castañeda-Noa, I., Eggli, U., Eriksson, R., Flores-Olvera, H., Fuentes-Bazán, S., Kadereit, G., Klak, C., Korotkova, N., Nyffeler, R., Ocampo, G., Ochoterena, H., Oxelman, B., Rabeler, R.K., Sanchez, A., Schlumpberger, B.O. & Uotila, P. (2015) A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales. <em>Willdenowia</em> 45: 281–383. https://doi.org/10.3372/wi.45.45301</p>
<p>Judd, W.S. (1981) A monograph of <em>Lyonia</em> (Ericaceae). <em>Journal of the Arnold Arboretum </em>62 (3): 315–436. https://doi.org/10.5962/bhl.part.11246</p>
<p>Judd, W.S. (2007) Revision of <em>Miconia</em> sect. <em>Chaenopleura</em> (Miconieae, Melastomataceae) in the Greater Antilles. <em>Systematic Botany Monographs</em> 81: 1–235.</p>
<p>Kim, I. (2012) Anatomical and morphological features of seeds in <em>Portulaca</em>. <em>Applled Microscopy</em> 42 (4): 194–199. https://doi.org/10.9729/AM.2012.42.4.194</p>
<p>Legrand, D. (1962) Las especies americanas de <em>Portulaca</em>. <em>Anales del Museo de Historia Natural de Montevideo</em> 7 (3): 9–147.</p>
<p>León, Hno. & Alain, Hno. (1950) Novedades de la Flora Cubana (II). <em>Contribuciones Ocasionales del Museo de Historia Natural del Colegio “De La Salle”</em> 9: 9–424.</p>
<p>Matthews, J.F. (2003) <em>Portulaca</em>. <em>In:</em> Flora of North America Editorial Committee. (Ed.) <em>Flora of North America</em>, vol. 4<em>.</em> Oxford University Press, New York, pp. 496–501.</p>
<p>Matthews, J.F. & Levins, P.A. (1985a) The genus <em>Portulaca</em> in the southeastern United States. <em>Castanea</em> 50 (2): 96–104.</p>
<p>Matthews, J.F. & Levins, P.A. (1985b) <em>Portulaca pilosa</em> L., <em>P. mundula</em> I.M. Johnst. and <em>P. parvula</em> Gray in the southwest. <em>Sida</em> 11 (1): 45–61.</p>
<p>Matthews, J.F. & Levins, P.A. (1986) The systematic significance of seed morphology in <em>Portulaca</em> (Portulacaceae) under scanning electron microscopy. <em>Systematic Botany</em> 11 (2): 302–308. http://dx.doi.org/10.2307/2419120</p>
<p>Matthews, J.F., Ketron, D.W. & Zane, S.F. (1993) The biology and taxonomy of the <em>Portulaca oleracea</em> L. (Portulacaceae) complex in North America. <em>Rhodora</em> 95 (882): 166–183.</p>
<p>Matilla, A., Gallardo, M. and Puga-Hermida, M.I. (2005) Structural, physiological and molecular aspects of heterogeneity in seeds: a review. <em>Seed Science Research</em> 15: 63–76. http://dx.doi.org/10.1079/SSR2005203</p>
<p>Murley, M.R. (1951) Seeds of the Cruciferae of northeastern North America. <em>American Midland Naturalist</em> 46: 1–81. http://dx.doi.org/10.2307/2421948</p>
<p>Nixon, K.C. & Wheeler, Q.D. (1990) An amplification of the phylogenetics species concept. <em>Cladistics</em> 6: 211–223. https://doi.org/10.1111/j.1096-0031.1990.tb00541.x</p>
<p>Nyffeler, R. & Eggli, U. (2010) Disintegrating Portulacaceae: A new familial classification of the suborder Portulacineae (Caryophyllales) based on molecular and morphological data. <em>Taxon</em> 59: 227–240. https://doi.org/10.1002/tax.591021</p>
<p>Ocampo, G. (2013) Morphological characterization of seeds in Portulacaceae. <em>Phytotaxa</em> 14: 1–24. http://dx.doi.org/10.11646/phytotaxa.141.1.1</p>
<p>Ocampo, G. (2014) Systematic implications of seed morphological diversity in Portulacaceae (Caryophyllales). <em>Plant Systematics and Evolution </em>301 (4): 1215–1226. http://dx.doi.org/10.1007/s00606-014-1146-1</p>
<p>Ocampo, G. & Columbus, J.T. (2012) Molecular phylogenetics, historical biogeography, and chromosome number evolution of <em>Portulaca</em> (Portulacaceae). <em>Molecular Phylogenetics and Evolution </em>63: 97–112. http://dx.doi.org/10.1016/j.ympev.2011.12.017</p>
<p>Ortega, M.D. (1985) Aspectos fitogeográficos y ecológicos del género <em>Portulaca</em> L. en Cuba. <em>Feddes Repertorium </em>96: 713–719. https://doi.org/10.1002/fedr.4910960735</p>
<p>Regalado, L., Ventosa, I. & Morejón, R. (2008) Revisión histórica de los herbarios cubanos con énfasis en las series de especímenes. <em>Revista del Jardín Botánico Nacional </em>29: 101–138.</p>
<p>Ricceri, C. & Arrigoni, P.V. (2000) L’aggregato di <em>Portulaca oleracea</em> L. (Portulacaceae). <em>Parlatorea</em> 4: 91–97.</p>
<p>Santos, T.A.V. (2016) <em>Estudos micromorfológicos em </em>Portulaca<em> L. (Portulacaceae) do Brasil.</em> Universidade Estadual de Feira de Santana, Feira de Santana, 92 pp.</p>
<p>Santos, T.A.V., Coelho, A.A.O.P., Dórea, M.C., Santos, F.A.R., Leite, K.R.B. & Oliveira, R.P. (2016) Micromorphological features revealing two new species of <em>Portulaca</em> (Portulacaceae) from Brazil, segregated from <em>P. hirsutissima</em>. <em>Phytotaxa</em> 270 (2): 103–115. http://dx.doi.org/10.11646/phytotaxa.270.2.3</p>
<p>StatSoft. (2011) <em>Statistica: data analysis software system, v.10. </em>StatSoft, Tulsa. Available from: http://www.statsoft.com (accessed 17 June 2021)</p>
<p>Stearn, W.T. (2004) <em>Botanical Latin</em> <em>4<sup>th</sup> ed</em>. Timber Press, Portland, 546 pp.</p>
<p>Thiers, B.M. (2021 onwards) <em>Index Herbariorum: A global directory of public herbaria and associated staff</em>. <em>New York Botanical Garden’s Virtual Herbarium</em>. Available from: http://sweetgum.nybg.org/ih. (accessed 17 June 2021)</p>
<p>Walter, J., Vekslyarska, T. & Dobeš, C. (2015) Flow cytometric, chromosomal and morphometric analyses challenge current taxonomic concepts in the <em>Portulaca oleracea</em> complex (Portulacaeae, Caryophyllales). <em>Botanical Journal of the Linnean Society</em> 179: 144–156. https://doi.org/10.1111/boj.12309</p>
<p>Wheeler, Q.D. & Platnick, N.I. (2000) The phylogenetic species concept (sensu Wheeler and Platnick). <em>In:</em> Wheeler, Q.D. & Meier, R. (Eds.) <em>Species concepts and phylogenetic theory: A debate.</em> Columbia University Press, New York, pp. 55–69.</p>
<p>Wilson, P. (1932) <em>Portulaca</em>. <em>In:</em> Britton, N.L., Murrill, W.A. & Barnhart, J.H. (Ed.) <em>North American Flora</em>, vol. 21. The New York Botanical Garden, New York, pp. 328–336.</p>
<p>Barthlott, W. (1981) Epidermal seed surface characters of plants: systematic applicability and some evolutionary aspects. <em>Nordic Journal of Botany</em> 1: 345–355. https://doi.org/10.1111/j.1756-1051.1981.tb00704.x</p>
<p>Coelho, A.A.O.P. & Giulietti, A.M. (2010) O gênero <em>Portulaca</em> L. (Portulacaceae) no Brasil. <em>Acta Botanica Brasilica </em>24 (3): 655–670. https://doi.org/10.1590/S0102-33062010000300009</p>
<p>Dalavi, J.V., Chougule, R.N., Jadhav, V.D. & Yadav, S.R. (2019) Variation in Seed Micromorphology in Portulaca L. (Portulacaceae) in India. <em>Phytomorphology</em> 69 (1 & 2): 15–24.</p>
<p>Danin, A. & Anderson, L.C. (1986) Distribution of <em>Portulaca oleracea</em> L. (Portulacaceae) subspecies in Florida. <em>Sida</em> 11 (3): 318–324. [https://www.jstor.org/stable/23909826]</p>
<p>Danin, A. & Reyes-Betancort, J.A. (2006) The status of <em>Portulaca oleracea</em> L. in Tenerife, the Canary Islands. <em>Lagascalia</em> 26: 71–81.</p>
<p>Danin, A. & Raus, T. (2012) A key to 19 microspecies of the <em>Portulaca oleracea</em> aggregate. <em>In:</em> Timonin, A.K., Sukhorukov, A.P., Harper, G.H. & Nilova, M.V. (Eds.) <em>Caryophyllales: New insights into phylogeny, systematics, and morphological evolution of the order, Proceedings of the Symposium held on 24th–27th September 2012</em>. Lomonosov State University, Moscow, pp. 70–83.</p>
<p>Danin, A., Baker, I. & Baker, H.G. (1978) Cytogeography and taxonomy of the <em>Portulaca oleracea</em> L. polyploid complex. <em>Israel Journal of Botany</em> 27: 177–211.</p>
<p>Danin, A., Domina, G. & Raimondo, F.M. (2008) Microspecies of the <em>Portulaca oleracea</em> aggregate found on major Mediterranean islands (Sicily, Cyprus, Crete, Rhodes). <em>Flora Mediterranea </em>18: 89–107.</p>
<p>Danin, A., Buldrini, F., Bandini, M. & Bosi, G. (2014) The history of the <em>Portulaca oleracea</em> aggregate in the Emilia-Romagna Po Plain (Italy) from the Roman Age to the present. <em>Plant Biosystems</em> 148 (4): 622–634. http://dx.doi.org/10.1080/11263504.2013.788098</p>
<p>Danin, A., Buldrini, F., Bandini Mazzanti, M., Bosi, G., Caria, M.C., Dandria, D., Lanfranco, E., Mifsud, S. & Bagella, S. (2016) Diversification of <em>Portulaca oleracea</em> L. complex in the Italian peninsula and adjacent islands. <em>Botany Letters</em> 163: 261–272. https://doi.org/10.1080/23818107.2016.1200482</p>
<p>Denis, D. & Ramírez-Arrieta, V.M. (2020) Si una imagen vale más que mil palabras: ¿cuánto puede decir un gráfico de cajas? <em>Revista del Jardín Botánico Nacional</em> 41: 57–69.</p>
<p>Eggli, U. & Ford-Werntz, D. (2002) Portulacaceae. <em>In</em>: Eggli, U. & Ford-Werntz, D. (Eds.) <em>Illustrated Handbook of Succulent Plants-Dicotyledons</em>. Springer, New York, pp. 370–432. https://doi.org/10.1007/978-3-642-56316-4_48</p>
<p>El-Bakatoushi, R., Alframawy, A.M., Samer, M., El-Sadek, L. & Botros, W. (2013) Evolution of the <em>Portulaca</em> <em>oleracea</em> L. aggregate in Egypt on molecular and phenotypic levels revealed by morphology, inter-simple sequence repeat (ISSR) and 18S rDNA gene sequence markers. <em>Flora</em> 208: 464–477. https://doi.org/10.1016/j.flora.2013.07.008</p>
<p>García-Beltrán, J.A., Barrios, D., Toledo, S. & Testé, E. (2020) Distribución y conservación de <em>Portulaca</em> (Portulacaceae) en Cuba. <em>Botanical Sciences</em> 98 (3): 597–617. https://doi.org/10.17129/botsci.2545</p>
<p>García-Beltrán, J.A., Barrios, D. & Bécquer, E.R. (2021) Revisión taxonómica de Portulacaceae en Cuba. <em>Brittonia</em> 73 (3): 1–31. https://doi.org/10.1007/s12228-021-09653-0</p>
<p>Hernández-Ledesma, P., Berendsohn, W.G., Borsch, Th., Mering, S., Akhani, H., Arias, S., Castañeda-Noa, I., Eggli, U., Eriksson, R., Flores-Olvera, H., Fuentes-Bazán, S., Kadereit, G., Klak, C., Korotkova, N., Nyffeler, R., Ocampo, G., Ochoterena, H., Oxelman, B., Rabeler, R.K., Sanchez, A., Schlumpberger, B.O. & Uotila, P. (2015) A taxonomic backbone for the global synthesis of species diversity in the angiosperm order Caryophyllales. <em>Willdenowia</em> 45: 281–383. https://doi.org/10.3372/wi.45.45301</p>
<p>Judd, W.S. (1981) A monograph of <em>Lyonia</em> (Ericaceae). <em>Journal of the Arnold Arboretum </em>62 (3): 315–436. https://doi.org/10.5962/bhl.part.11246</p>
<p>Judd, W.S. (2007) Revision of <em>Miconia</em> sect. <em>Chaenopleura</em> (Miconieae, Melastomataceae) in the Greater Antilles. <em>Systematic Botany Monographs</em> 81: 1–235.</p>
<p>Kim, I. (2012) Anatomical and morphological features of seeds in <em>Portulaca</em>. <em>Applled Microscopy</em> 42 (4): 194–199. https://doi.org/10.9729/AM.2012.42.4.194</p>
<p>Legrand, D. (1962) Las especies americanas de <em>Portulaca</em>. <em>Anales del Museo de Historia Natural de Montevideo</em> 7 (3): 9–147.</p>
<p>León, Hno. & Alain, Hno. (1950) Novedades de la Flora Cubana (II). <em>Contribuciones Ocasionales del Museo de Historia Natural del Colegio “De La Salle”</em> 9: 9–424.</p>
<p>Matthews, J.F. (2003) <em>Portulaca</em>. <em>In:</em> Flora of North America Editorial Committee. (Ed.) <em>Flora of North America</em>, vol. 4<em>.</em> Oxford University Press, New York, pp. 496–501.</p>
<p>Matthews, J.F. & Levins, P.A. (1985a) The genus <em>Portulaca</em> in the southeastern United States. <em>Castanea</em> 50 (2): 96–104.</p>
<p>Matthews, J.F. & Levins, P.A. (1985b) <em>Portulaca pilosa</em> L., <em>P. mundula</em> I.M. Johnst. and <em>P. parvula</em> Gray in the southwest. <em>Sida</em> 11 (1): 45–61.</p>
<p>Matthews, J.F. & Levins, P.A. (1986) The systematic significance of seed morphology in <em>Portulaca</em> (Portulacaceae) under scanning electron microscopy. <em>Systematic Botany</em> 11 (2): 302–308. http://dx.doi.org/10.2307/2419120</p>
<p>Matthews, J.F., Ketron, D.W. & Zane, S.F. (1993) The biology and taxonomy of the <em>Portulaca oleracea</em> L. (Portulacaceae) complex in North America. <em>Rhodora</em> 95 (882): 166–183.</p>
<p>Matilla, A., Gallardo, M. and Puga-Hermida, M.I. (2005) Structural, physiological and molecular aspects of heterogeneity in seeds: a review. <em>Seed Science Research</em> 15: 63–76. http://dx.doi.org/10.1079/SSR2005203</p>
<p>Murley, M.R. (1951) Seeds of the Cruciferae of northeastern North America. <em>American Midland Naturalist</em> 46: 1–81. http://dx.doi.org/10.2307/2421948</p>
<p>Nixon, K.C. & Wheeler, Q.D. (1990) An amplification of the phylogenetics species concept. <em>Cladistics</em> 6: 211–223. https://doi.org/10.1111/j.1096-0031.1990.tb00541.x</p>
<p>Nyffeler, R. & Eggli, U. (2010) Disintegrating Portulacaceae: A new familial classification of the suborder Portulacineae (Caryophyllales) based on molecular and morphological data. <em>Taxon</em> 59: 227–240. https://doi.org/10.1002/tax.591021</p>
<p>Ocampo, G. (2013) Morphological characterization of seeds in Portulacaceae. <em>Phytotaxa</em> 14: 1–24. http://dx.doi.org/10.11646/phytotaxa.141.1.1</p>
<p>Ocampo, G. (2014) Systematic implications of seed morphological diversity in Portulacaceae (Caryophyllales). <em>Plant Systematics and Evolution </em>301 (4): 1215–1226. http://dx.doi.org/10.1007/s00606-014-1146-1</p>
<p>Ocampo, G. & Columbus, J.T. (2012) Molecular phylogenetics, historical biogeography, and chromosome number evolution of <em>Portulaca</em> (Portulacaceae). <em>Molecular Phylogenetics and Evolution </em>63: 97–112. http://dx.doi.org/10.1016/j.ympev.2011.12.017</p>
<p>Ortega, M.D. (1985) Aspectos fitogeográficos y ecológicos del género <em>Portulaca</em> L. en Cuba. <em>Feddes Repertorium </em>96: 713–719. https://doi.org/10.1002/fedr.4910960735</p>
<p>Regalado, L., Ventosa, I. & Morejón, R. (2008) Revisión histórica de los herbarios cubanos con énfasis en las series de especímenes. <em>Revista del Jardín Botánico Nacional </em>29: 101–138.</p>
<p>Ricceri, C. & Arrigoni, P.V. (2000) L’aggregato di <em>Portulaca oleracea</em> L. (Portulacaceae). <em>Parlatorea</em> 4: 91–97.</p>
<p>Santos, T.A.V. (2016) <em>Estudos micromorfológicos em </em>Portulaca<em> L. (Portulacaceae) do Brasil.</em> Universidade Estadual de Feira de Santana, Feira de Santana, 92 pp.</p>
<p>Santos, T.A.V., Coelho, A.A.O.P., Dórea, M.C., Santos, F.A.R., Leite, K.R.B. & Oliveira, R.P. (2016) Micromorphological features revealing two new species of <em>Portulaca</em> (Portulacaceae) from Brazil, segregated from <em>P. hirsutissima</em>. <em>Phytotaxa</em> 270 (2): 103–115. http://dx.doi.org/10.11646/phytotaxa.270.2.3</p>
<p>StatSoft. (2011) <em>Statistica: data analysis software system, v.10. </em>StatSoft, Tulsa. Available from: http://www.statsoft.com (accessed 17 June 2021)</p>
<p>Stearn, W.T. (2004) <em>Botanical Latin</em> <em>4<sup>th</sup> ed</em>. Timber Press, Portland, 546 pp.</p>
<p>Thiers, B.M. (2021 onwards) <em>Index Herbariorum: A global directory of public herbaria and associated staff</em>. <em>New York Botanical Garden’s Virtual Herbarium</em>. Available from: http://sweetgum.nybg.org/ih. (accessed 17 June 2021)</p>
<p>Walter, J., Vekslyarska, T. & Dobeš, C. (2015) Flow cytometric, chromosomal and morphometric analyses challenge current taxonomic concepts in the <em>Portulaca oleracea</em> complex (Portulacaeae, Caryophyllales). <em>Botanical Journal of the Linnean Society</em> 179: 144–156. https://doi.org/10.1111/boj.12309</p>
<p>Wheeler, Q.D. & Platnick, N.I. (2000) The phylogenetic species concept (sensu Wheeler and Platnick). <em>In:</em> Wheeler, Q.D. & Meier, R. (Eds.) <em>Species concepts and phylogenetic theory: A debate.</em> Columbia University Press, New York, pp. 55–69.</p>
<p>Wilson, P. (1932) <em>Portulaca</em>. <em>In:</em> Britton, N.L., Murrill, W.A. & Barnhart, J.H. (Ed.) <em>North American Flora</em>, vol. 21. The New York Botanical Garden, New York, pp. 328–336.</p>