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Issue: Vol. 619 No. 1: 5 Oct. 2023
Type: Article
Published: 2023-10-05
DOI: 10.11646/phytotaxa.619.1.3
Page range: 63-85
Abstract views: 128
PDF downloaded: 9

Hypoxis limicola and H. uniflorata (Hypoxidaceae) deserve species rank: multiple new lines of evidence

School of Animal; Plant and Environmental Sciences; University of the Witwatersrand; Johannesburg; South Africa
School of Animal; Plant and Environmental Sciences; University of the Witwatersrand; Johannesburg; South Africa
School of Animal; Plant and Environmental Sciences; University of the Witwatersrand; Johannesburg; South Africa
Monocots Asparagales endemic grassland Hypoxidaceae South Africa species complex variety

Abstract

Hypoxis, the largest genus within the Hypoxidaceae, has its primary centre of diversity and endemism within southern Africa. The taxonomy of the genus has always presented a challenge due to a lack of distinct diagnostic characters that readily define species and infraspecific taxa—with polyploidy, hybridization, and apomixis thought to contribute substantially to these challenges. This holds true for the informally designated Hypoxis parvula species complex—a group of five soft-leaved taxa (H. parvula var. parvula, H. parvula var. albiflora, H. limicola, H. uniflorata, and H. membranacea) that have been treated as distinct by some authors and have variously been reduced to synonyms by others. Here, the taxonomic status of lineages within this complex is evaluated using flow cytometry, morphological, environmental, and molecular data. Specifically, it is evaluated whether there is sufficient support to resurrect Hypoxis limicola and to uphold the little-known H. uniflorata. Differences in relative genome size estimates between H. limicola and the H. parvula varieties, as well as environmental data, suggest that H. limicola exists outside the ecological habitat of both H. parvula varieties, which supports the distinctness of these two species. Results from the phylogenetic analysis based on cpDNA regions (rbcL, trnS-G, and trnL-F) showed that H. limicola, H. parvula, and H. uniflorata formed distinct, well supported clades within Hypoxis. Hypoxis membranacea did not resolve with any members of the H. parvula species complex, but instead formed a clade with H. angustifolia—a taxon with which it overlaps morphologically and ecologically, and with which it is thought to hybridize. Collectively, the data supports reinstatement of H. limicola and recognition of H. uniflorata as a distinct species. Descriptions with updated notes on habitat, distribution, relationships, and diagnostic features are provided for the focal taxa in this study, together with an identification key.

 

References

  1. Adams, K.L. & Wendel, J.F. (2005) Polyploidy and genome evolution in plants. Current Opinion in Plant Biology 8 (2): 135–141. https://doi.org/10.1016/j.pbi.2005.01.001
  2. Baker, J.G. (1876) On new bulbous plants from the eastern provinces of the Cape Colony. Journal of Botany, British and Foreign 14: 181–184. [https://www.biodiversitylibrary.org/page/9103370#page/203/mode/1up]
  3. Baker, J.G. (1878) A synopsis of Hypoxidaceae. Journal of the Linnean Society (Botany) 17 (99): 93–126. https://doi.org/10.1111/j.1095-8339.1878.tb01247.x
  4. Baker, J.G. (1894) CCCCXII. Decades Kewensis: Plantarum Novarum in Herbario Horti Regii Conservatarum. Decas X. Bulletin of Miscellaneous Information 1894 (94): 353–358. https://doi.org/10.2307/4118323
  5. Baker, J.G. (1896) Order CXXXV. Amaryllidaceae. III. Hypoxis Linn. In: Thiselton-Dyer, W.T. (Ed.) Flora capensis 6. Lovell Reeve & Co., London, pp. 174–189. [https://www.biodiversitylibrary.org/item/15237#page/182/mode/1up]
  6. Balao, F., Herrera, J. & Talavera, S. (2011) Phenotypic consequences of polyploidy and genome size at the microevolutionary scale: a multivariate morphological approach. New Phytologist 192 (1): 256–265. https://doi.org/10.1111/j.1469-8137.2011.03787.x
  7. Barthlott, W. (1981) Epidermal and seed surface characters of plants: systematic applicability and some evolutionary aspects. Nordic Journal of Botany 1 (3): 345–355. https://doi.org/10.1111/j.1756-1051.1981.tb00704.x
  8. Beck, J.B., Windham, M.D., Yatskievych, G. & Pryer, K.M. (2010) A diploids-first approach to species delimitation and interpreting polyploid evolution in the fern genus Astrolepis (Pteridaceae). Systematic Botany 35 (2): 223–234. https://doi.org/10.1600/036364410791638388
  9. Bennett, M.D. & Leitch, I.J. (2005) Nuclear DNA amounts in angiosperms: progress, problems and prospects. Annals of Botany 95 (1): 45–90. https://doi.org/10.1093/aob/mci003
  10. Brackett, A. (1923) Revision of the American species of Hypoxis. Rhodora 25: 120–147, 151–155.
  11. Brandrud, M.K., Baar, J., Lorenzo, M.T., Athanasiadis, A., Bateman, R.M., Chase, M.W., Hedrén, M. & Paun, O. (2020) Phylogenomic relationships of diploids and the origins of allotetraploids in Dactylorhiza (Orchidaceae). Systematic Biology 69 (1): 91–109. https://doi.org/10.1093/sysbio/syz035
  12. Brown, A.H.D., Doyle, J.L., Grace, J.P. & Doyle, J.J. (2002) Molecular phylogenetic relationships within and among diploid races of Glycine tomentella (Leguminosae). Australian Systematic Botany 15 (1): 37–47. https://doi.org/10.1071/SB01003
  13. Carstens, B.C., Pelletier, T.A., Reid, N.M. & Satler, J.D. (2013) How to fail at species delimitation. Molecular Ecology 22 (17): 4369–4383. https://doi.org/10.1111/mec.12413
  14. Chen, Z.J. (2007) Genetic and epigenetic mechanisms for gene expression and phenotypic variation in plant polyploids. Annual Review of Plant Biology 58: 377–406. https://doi.org/10.1146/annurev.arplant.58.032806.103835
  15. Chernomor, O., Von Haeseler, A. & Minh, B.Q. (2016) Terrace aware data structure for phylogenomic inference from supermatrices. Systematic Biology 65 (6): 997–1008. https://doi.org/10.1093/sysbio/syw037
  16. Dayrat, B. (2005) Towards integrative taxonomy. Biological Journal of the Linnean Society 85 (3): 407–415. https://doi.org/10.1111/j.1095-8312.2005.00503.x
  17. De Queiroz, K. (2005) Different species problems and their resolution. BioEssays 27 (12): 1263–1269. https://doi.org/10.1002/bies.20325
  18. De Queiroz, K. (2007) Species concepts and species delimitation. Systematic Biology 56 (6): 879–886. https://doi.org/10.1080/10635150701701083
  19. Doležel, J. & Bartoš, J. (2005) Plant DNA flow cytometry and estimation of nuclear genome size. Annals of Botany 95 (1): 99–110. https://doi.org/10.1093/aob/mci005
  20. Fay, M.F., Swensen, S.M. & Chase, M.W. (1997) Taxonomic affinities of Medusagyne oppositifolia (Medusagynaceae). Kew Bulletin 52 (1): 111–120. https://doi.org/10.2307/4117844
  21. Fazekas, A.J., Kesanakurti, P.R., Burgess, K.S., Percy, D.M., Graham, S.W., Barrett, S.C.H., Newmaster, S.G., Hajibabaei, M. & Husband, B.C. (2009) Are plant species inherently harder to discriminate than animal species using DNA barcoding markers? Molecular Ecology Resources 9 (s1): 130–139. https://doi.org/10.1111/j.1755-0998.2009.02652.x
  22. Felsenstein, J. (1985) Confidence limits on phylogenies: an approach using the bootstrap. Evolution 39 (4): 783–791. https://doi.org/10.2307/2408678
  23. Fischer, F.E.L., Von Meyer, C.A. & Avé-Lallemant, J.L.E. (1842) 1502. Hypoxis hemerocallidea. Index seminum, quae Hortus Botanicus Imperialis Petropolitanus pro mutua commutatione offert: accedunt Animadversiones botanicae nonnullae 8: 64. [https://www.biodiversitylibrary.org/item/165156#page/412/mode/1up]
  24. Gates, R. (1909) The stature and chromosomes of Oenothera gigas De Vries. Archiv für Zellforschung 3: 525–552.
  25. GBIF Secretariat (2021) GBIF Backbone Taxonomy. Checklist dataset. Available from: https://doi.org/10.15468/39omei (accessed 12 April 2021).
  26. Geyer, C.J. (1991) Markov Chain Monte Carlo Maximum Likelihood. In: Keramidas, E.M. (Ed.) Computing science and statistics: Proceedings of the 23rd Symposium on the Interface. Interface Foundation of North America, Seattle, Washington, pp. 156–163.
  27. Govindarajulu, R., Hughes, C.E. & Bailey, C.D. (2011) Phylogenetic and population genetic analyses of diploid Leucaena (Leguminosae; Mimosoideae) reveal cryptic species diversity and patterns of divergent allopatric speciation. American Journal of Botany 98 (12): 2049–2063. https://doi.org/10.3732/ajb.1100259
  28. Hamilton, M.B. (1999) Four primer pairs for the amplification of chloroplast regions with intraspecific variation. Molecular Ecology 8: 521–523.
  29. Harvey, W.H. (1838) The genera of South African plants. A.S. Robertson, Cape Town, 429 pp.
  30. Heiss, A.G., Kropf, M., Sontag, S. & Weber, A. (2011) Seed morphology of Nigella s.l. (Ranunculaceae): identification, diagnostic traits, and their potential phylogenetic relevance. International Journal of Plant Sciences 172 (2): 267–284. https://doi.org/10.1086/657676
  31. Henderson, R.J.F. (1987) Hypoxis. Flora of Australia 45: 178–190, 220.
  32. Herndon, A. (1992) The genus Hypoxis (Hypoxidaceae) in Florida. Florida Scientist 55: 45–55.
  33. Herndon, A. (2002) Hypoxis. In: Flora of North America Editorial Committee (Eds.) Flora of North America North of Mexico, vol. 26. Magnoliophyta: Lilidae: Liliales and Orchidales. Oxford University Press, New York, pp. 201–204.
  34. Hilliard, O.M. & Burtt, B.L. (1975) Notes on some plants of southern Africa chiefly from Natal. IV. Notes from the Royal Botanic Garden, Edinburgh 34: 73.
  35. Hilliard, O.M. & Burtt, B.L. (1978) Notes on some plants from southern Africa chiefly from Natal: VII. Notes from the Royal Botanic Garden, Edinburgh 36: 43–76.
  36. Hilliard, O.M. & Burtt, B.L. (1988) Notes on some plants from southern Africa chiefly from Natal: XV. Notes from the Royal Botanic Garden, Edinburgh 45: 179–223.
  37. Hoang, D.T., Chernomor, O., Von Haeseler, A., Minh, B.Q. & Vinh, L.S. (2017) UFBoot2: Improving the Ultrafast Bootstrap Approximation. Molecular Biology and Evolution 35 (2): 518–522. https://doi.org/10.1093/molbev/msx281
  38. Hollingsworth, P.M., Graham, S.W. & Little, D.P. (2011) Choosing and using a plant DNA Barcode. PLoS ONE 6: e19254. https://doi.org/10.1371/journal.pone.0019254
  39. Kalyaanamoorthy, S., Minh, B.Q., Wong, T.K.F., Von Haeseler, A. & Jermiin, L.S. (2017) ModelFinder: fast model selection for accurate phylogenetic estimates. Nature Methods 14: 587–589. https://doi.org/10.1038/nmeth.4285
  40. Katoh, K. & Standley, D.M. (2013) MAFFT multiple sequence alignment software version 7: Improvements in performance and usability. Molecular Biology and Evolution 30 (4): 772–780. https://doi.org/10.1093/molbev/mst010
  41. Kearse, M., Moir, R., Wilson, A., Stones-Havas, S., Cheung, M., Sturrock, S., Buxton, S., Cooper, A., Markowitz, S., Duran, C., Thierer, T., Ashton, B., Mentjies, P. & Drummond, A. (2012) Geneious basic: an integrated and extendable desktop software platform for the organization and analysis of sequence data. Bioinformatics 28 (12): 1647–1649. https://doi.org/10.1093/bioinformatics/bts199
  42. Kocyan, A., Snijman, D.A., Forest, F., Devey, D.S., Freudenstein, J.V., Wiland-Szymańska, J., Chase, M.W. & Rudall, P.J. (2011) Molecular phylogenetics of Hypoxidaceae—Evidence from plastid DNA data and inferences on morphology and biogeography. Molecular Phylogenetics and Evolution 60 (1): 122–136. https://doi.org/10.1016/j.ympev.2011.02.021
  43. Lamarck, J.B.A.P. de M. (1789) Encyclopédie Méthodique, Botanique, vol. 3. Panckoucke, Paris, 759 pp. https://doi.org/10.5962/bhl.title.824
  44. Lamarck, J.B.A.P. de M. (Ed.) (1798) Encyclopédie Méthodique, Botanique, vol. 4 (2). Panckoucke, Paris, 353 pp. https://doi.org/10.5962/bhl.title.824
  45. Linnaeus, C. (1759) Systema Naturae (10th edition), vol. 2. Laurentii Salvii, Stockholm, 559 pp. https://doi.org/10.5962/bhl.title.542
  46. Liu, K.-W., Xie, G.-C., Chen, L.-J., Xiao, X.-J., Zheng, Y.-Y., Cai, J., Zhai, J.-W., Zhang, G.-Q. & Liu, Z.-J. (2012) Sinocurculigo, a new genus of Hypoxidaceae from China based on molecular and morphological evidence. PLoS ONE 7: e38880. https://doi.org/10.1371/journal.pone.0038880
  47. Markötter, E.I. (1930) ‘n Plantgeografiese skets en die Flora van Witzieshoek, O.V.S. Annale van die Universiteit van Stellenbosch 8 (1): 1–50.
  48. Mathew, B.F. (1998) ×Rhodoxis hybrida. Quarterly Bulletin of the Alpine Garden Society of Great Britain 66: 441.
  49. McVaugh, R. (1989) Hypoxis L. In: Anderson, W.R. (Ed.) Flora Novo-Galiciana, vol. 15: Bromeliaceae to Dioscoreaceae. University of Michigan Herbarium, Ann Arbor, pp. 219–227.
  50. Miller, M.A., Pfeiffer, W. & Schwartz, T. (2010) Creating the CIPRES science gateway for inference of large phylogenetic trees. In: 2010 Gateway Computing Environments Workshop (GCE) Proceedings. pp. 1–8. https://doi.org/10.1109/GCE.2010.5676129
  51. Minh, B.Q., Nguyen, M.A.T. & Von Haeseler, A. (2013) Ultrafast approximation for phylogenetic bootstrap. Molecular Biology and Evolution 30 (5): 1188–1195. https://doi.org/10.1093/molbev/mst024
  52. Minh, B.Q., Schmidt, H.A., Chernomor, O., Schrempf, D., Woodhams, M.D., Von Haeseler, A., Lanfear, R. & Teeling, E. (2020) IQ-TREE 2: new models and efficient methods for phylogenetic inference in the genomic era. Molecular Biology and Evolution 37 (5): 1530–1534. https://doi.org/10.1093/molbev/msaa015
  53. Mitchell, N. & Holsinger, K.E. (2018) Cryptic natural hybridization between two species of Protea. South African Journal of Botany 118: 306–314. https://doi.org/10.1016/j.sajb.2017.12.002
  54. Naciri, Y. & Linder, H.P. (2015) Species delimitation and relationships: The dance of the seven veils. Taxon 64 (1): 3–16. https://doi.org/10.12705/641.24
  55. Nel, G.C. (1914) Beiträge zur Flora von Africa XLIII. Studien über die Amaryllidaceae—Hypoxideae, unter besonderer Berücksichtigung der afrikanischen Arten. Botanische Jahrbücher fur Systematik, Pflanzengeschichte und Pflanzengeographie 51: 234–340. [https://www.biodiversitylibrary.org/page/189141#page/334/mode/1up]
  56. Nguyen, L.T., Schmidt, H.A., Von Haeseler, A. & Minh, B.Q. (2015) IQ-TREE: A fast and effective stochastic algorithm for estimating maximum-likelihood phylogenies. Molecular Biology and Evolution 32 (1): 268–274. https://doi.org/10.1093/molbev/msu300
  57. Nordal, I. & Kativu, S. (1999) New systematics within superorder Lilianae: consequences for the tropical African flora projects. In: Timberlake, J. & Kativu, S. (Eds.) African plants: Biodiversity, taxonomy and uses. Royal Botanic Gardens, Kew, pp. 291–308.
  58. Nordal, I., Laane, M.M., Holt, E. & Staubo, I. (1985) Taxonomic studies of the genus Hypoxis in East Africa. Nordic Journal of Botany 5 (1): 15–30. https://doi.org/10.1111/j.1756-1051.1985.tb02067.x.
  59. Olmstead, R.G., Michaels, H.J., Scott, K.M. & Palmer, J.D. (1992) Monophyly of the Asteridae and identification of their major lineages inferred from DNA sequences of rbcL. Annals of the Missouri Botanical Garden 79 (2): 249–265. https://doi.org/10.2307/2399768
  60. Padilla-García, N., Rojas-Andrés, B.M., López-González, N., Castro, M., Castro, S., Loureiro, J., Albach, D.C., Machon, N. & Montserrat Martínez-Ortega, M. (2018) The challenge of species delimitation in the diploid-polyploid complex Veronica subsection Pentasepalae. Molecular Phylogenetics and Evolution 119: 196–209. https://doi.org/10.1016/j.ympev.2017.11.007
  61. R Core Team (2022) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Available from: https://www.R-project.org/ (accessed 6 July 2022).
  62. Rambaut, A., Drummond, A.J., Xie, D., Baele, G. & Suchard, M.A. (2018) Posterior summarization in Bayesian phylogenetics using Tracer 1.7. Systematic Biology 67 (5): 901–904. https://doi.org/10.1093/sysbio/syy032
  63. Ramsey, J. & Schemske, D.W. (1998) Pathways, mechanisms, and rates of polyploid formation in flowering plants. Annual Review of Ecology and Systematics 29: 467–501. https://doi.org/10.1146/annurev.ecolsys.29.1.467
  64. Ronquist, F. & Huelsenbeck, J.P. (2003) MrBayes 3: Bayesian phylogenetic inference under mixed models. Bioinformatics 19 (12): 1572–1574. https://doi.org/10.1093/bioinformatics/btg180
  65. Saito, K. (1975) Studies on the occurrence of polyploidy and its contributions to the flower plant breeding. XII. On the nature and sterility in the spontaneous triploid cultivars of Rhodohypoxis baurii. Nel. Japanese Journal of Breeding 25: 355–362.
  66. Segraves, K.A. (2017) The effects of genome duplications in a community context. The New Phytologist 215 (1): 57–69. https://doi.org/10.1111/nph.14564
  67. Sigel, E.M., Windham, M.D., Haufler, C.H. & Pryer, K.M. (2014) Phylogeny, divergence time estimates, and phylogeography of the diploid species of the Polypodium vulgare complex (Polypodiaceae). Systematic Botany 39 (4): 1042–1055. https://doi.org/10.1600/036364414x683921
  68. Singh, Y. (2004) Getting to grips with Hypoxis. PlantLife 31: 30–33.
  69. Singh, Y. (2006) Hypoxis (Hypoxidaceae) in Africa: list of species and infraspecific names. Bothalia 36 (1): 13–23. https://doi.org/10.4102/abc.v36i1.327
  70. Singh, Y. (2009) Systematics of Hypoxis (Hypoxidaceae) in southern Africa. Unpublished Ph.D. thesis. University of Pretoria, Pretoria, South Africa, 360 pp. http://hdl.handle.net/2263/26382
  71. Singh, Y., Styles, D., Van Wyk, A.E. & Condy, G. (2007) Hypoxis nivea. Hypoxidaceae. Flowering Plants of Africa 60: 36–44.
  72. Sliwinska, E., Loureiro, J., Leitch, I.J., Šmarda, P., Bainard, J., Bureš, P., Chumová, Z., Horová, L., Koutecký, P., Lučanová, M., Trávníček, P. & Galbraith, D.W. (2022) Application-based guidelines for best practices in plant flow cytometry. Cytometry 101 (9): 749–781. https://doi.org/10.1002/cyto.a.24499
  73. South African National Biodiversity Institute [SANBI] (2022) BODATSA: Botanical Collections. Version 1.1.4. South African National Biodiversity Institute. Dataset/Occurrence. Available from: http://ipt.sanbi.org.za/iptsanbi/resource?r=brahms_online (accessed 24 October 2022).
  74. Stebbins, G.L. (1947) Types of polyploidy: their classification and significance. Advances in Genetics 1: 403–429. https://doi.org/10.1016/S0065-2660(08)60490-3
  75. Stebbins, G.L. (1971) Chromosomal evolution in higher plants. Edward Arnold Ltd., London, 216 pp.
  76. Stuessy, T.F., Crawford, D.J., Soltis, D.E. & Soltis, P.S. (2014) Plant Systematics: The origin, interpretation, and ordering of plant biodiversity. Koeltz Botanical Books, Köningstein, 425 pp.
  77. Suda, J. & Trávníček, P. (2006) Reliable DNA ploidy determination in dehydrated tissues of vascular plants by DAPI flow cytometry—new prospects for plant research. Cytometry A 69A(4): 273–280. https://doi.org/10.1002/cyto.a.20253
  78. Swofford, D.L. (2002) PAUP*: phylogenetic analysis using parsimony (*and other methods), version 4.0b10. Sinauer Associates, Massachusetts.
  79. Taberlet, P., Gielly, L., Pautou, G. & Bouvet, J. (1991) Universal primers for amplification of three non-coding regions of chloroplast DNA. Plant Molecular Biology 17: 1105–1109. https://doi.org/10.1007/BF00037152
  80. Taylor, S.A. & Larson, E.L. (2019) Insights from genomes into the evolutionary importance and prevalence of hybridization in nature. Nature Ecology & Evolution 3: 170–177. https://doi.org/10.1038/s41559-018-0777-y
  81. Thiers, B. (2021[continuously updated]) Index Herbariorum: A global directory of public herbaria and associated staff. Continuously updated. New York Botanical Garden’s Virtual Herbarium. Available from: http://sweetgum.nybg.org/science/ih/ (accessed 2021).
  82. Van de Peer, Y., Mizrachi, E. & Marchal, K. (2017) The evolutionary significance of polyploidy. Nature Reviews Genetics 18: 411–424. https://doi.org/10.1038/nrg.2017.26
  83. Wiland-Szymańska, J. (2001) The genus Hypoxis (Hypoxidaceae) in Central Africa. Annals of the Missouri Botanical Garden 88 (2): 302–350. https://doi.org/10.2307/2666228
  84. Wiland-Szymańska, J. (2006) Morphological variability of seeds in East African species of the genus Hypoxis L. (Hypoxidaceae). Biodiversity: Research and Conservation 1–2: 31–33.
  85. Wiland-Szymańska, J. (2009) The genus Hypoxis L. (Hypoxidaceae) in the East Tropical Africa: variability, distribution and conservation status. Biodiversity: Research and Conservation 14: 1–129. https://doi.org/10.2478/v10119-009-0011-5
  86. Wiland-Szymańska, J. & Adamski, Z. (2002) Taxonomic and morphological notes on Hypoxis angustifolia (Hypoxidaceae) from Africa, Madagascar, and Mauritius. Novon 12 (1): 142–151. https://doi.org/10.2307/3393254
  87. Wilsenach, R. (1967) Cytological observations in Hypoxis. I. Somatic chromosomes and meiosis in some Hypoxis species. Journal of South African Botany 33: 75–84.
  88. Wilsenach, R. & Papenfus, J.N. (1967) Cytological observations on Hypoxis: II. Pollen germination, pollen tube growth and haploid chromosome numbers in some Hypoxis species. Journal of South African Botany 33: 111–116.
  89. Wilsenach, R. & Warren, J.L. (1967) Cytological observations on Hypoxis: III. Embryo-sac development in Hypoxis rooperii and H. filfiformis. Journal of South African Botany 33: 133–140.
  90. Windham, M.D. & Al-Shehbaz, I.A. (2006) New and noteworthy species of Boechera (Brassicaceae) I: sexual diploids. Harvard Papers in Botany 11 (1): 61–88. https://doi.org/10.3100/1043-4534(2006)11[61:NANSOB]2.0.CO;2
  91. Wood, S.E. (1976) A contribution to knowledge of the genus Hypoxis L. (Hypoxidaceae) in Natal, South Africa. Unpublished M.Sc. thesis. University of Natal, Pietermaritzburg, South Africa, 121 pp.
  92. Zimudzi, C. (1994) The cytology and reproduction of the genus Hypoxis L. In: Seyani, J.H. & Chikuni, A.C. (Eds.) Proceedings of the XIIIth Plenary Meeting, AETFAT. National Herbarium and Botanic Gardens of Malawi, Zomba, pp. 535–543.
  93. Zona, S., Prince, J., Halder, G., Schwartz, R. & Vargas, R. (2009) A seed atlas of Hypoxis from eastern North America. The Journal of the Torrey Botanical Society 136 (1): 26–32. https://doi.org/10.3159/08-RA-086R.1