Preliminary Cytology of Australasian Iridaceae

Abstract

Native Australasian Iridaceae are poorly known cytologically with only Libertia, x = 19, well studied. In other genera Patersonia is shown to have n = 11 (not 12 as previously reported), 21 and 31, Diplarrhena has n = 15-16, and Orthrosanthus laxus, a high polyploid, n = 75-80. The only nonAfrican species of Dietes, D. robinsoniana, from Lord Howe Island, has n = 10 which agrees with x = 10 known for the African species. An artificial hybrid D. robinsoniana x D. iridioides also has n = 10. Affinities of the Autralasian Iridaceae are discussed in relation to the cytology and morphology. There are five or perhaps six native genera and some 26 species of Iridaceae in Australasia, few compared to the other southern continents where the family is well represented. Two Australasian genera, Libertia and Orthrosanthus are shared with South America and one, Dietes, with Africa, while Diplarrhena, Patersonia, and also Isophysis (if this is admitted to the family) are endemic. Patersonia actually extends to New Guinea and Borneo, though it is centered in temperate Australia. The affinities of the endemic genera are not clear, while the relationship of the Australasian species of Dietes to the rest of this essentially African genus has been the subject of considerable interest. Cytology has been of great value in interpreting relationships of Iridaceae in Africa (Goldblatt, 1971, 1976a) and seems likely to be of value in the New World also. The Australasian species and genera are hardly known cytologically except for Libertia (Hair et al., 1967), and with this in mind I have undertaken this study. Results to date have been somewhat meager but seem worth reporting, in spite of remaining gaps in the record. Hopefully results will stimulate further investigation of the family in Australasia. MATERIALS AND METHODS Seeds and plants of native Australian species were obtained from Kings Park and Botanic Garden, Perth; from Winifred Curtis and Desmond Morris, Tasmania; and from the Royal Botanic Gardens, Sydney. The hybrid Dietes robinsonia x D. iridioides was made by M. Boussard, Verdun, France, from parent plants of wild origin. Unfortunately, with few exceptions material is not represented by vouchers collected in the wild, and I have been able to make vouchers of only the few which grew to flowering at the Missouri Botanical Garden. All counts were made from mitotic preparations. Root tips obtained from actively growing plants were pretreated in 0.003 M hydroxy-quinoline, fixed in Carnoy's solution, hydrolyzed in 10o HCl for 6 minutes at 60'C and squashed 1 This study was supported by grants BMS 74-18905 and DEB 76-19907 from the United States National Science Foundation. I wish to thank Winifred Curtis and Desmond Morris of Tasmania for material of Diplarrhena studied, and Dr. M. Boussard for plants of his hybrid D. robinsoniana x D. iridioides. 2 B. A. Krukoff Curator of African Botany, Missouri Botanical Garden, Post Office Box 299, St. Louis, Missouri 63166. ANN. MISSOURI BOT. GARD. 66: 851-855. 1979. 0026-6493/79/0851-0855/$00.65/0 This content downloaded from 157.55.39.104 on Sun, 19 Jun 2016 05:55:54 UTC All use subject to http://about.jstor.org/terms 852 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 66 TABLE 1. Chromosome numbers in Australasian Iridaceae. Counts in bold type are new reports.