Abstract
The phylogeny of Crocoideae, the largest of four subfamilies currently recognized in Iridaceae, has eluded resolution until sequences of two more plastid DNA regions were added here to a previously published matrix containing sequences from four DNA plastid regions. Sister to the core Nivenioideae, the woody Klattia, Nivenia, and Witsenia, Crocoideae are a climax group in Iridaceae, comprising some 995 species, slightly more than half of the total in the family. Synapomorphies of Crocoideae include pollen exine perforate, pollen aperture operculate, ovule campylotropous (or hypotropous), root xylem vessels with simple perforations, cormous rootstock, inflorescence a spike, and plants deciduous. The six DNA region analysis here that includes examples of 27 of the 28 genera of the subfamily shows the southern African Tritoniopsis sister to the remaining genera, which resolve into four well-supported clusters (bootstrap support >85%). Each of these major clades is treated as a tribe, the synapomorphies of which are discussed in light of the molecular phylogenetic analyses. Original embryological and seed developmental studies largely support the tribal classification. Tritoniopsideae alone has the inner floral bracts not forked apically, and a hypotropous ovule, while this tribe and Watsonieae have axillary corm development. The remaining three tribes have apical corm development, and together with Watsonieae have a campylotropous ovule, and the inner layer of the inner integument crushed at maturity.
Highlights
One of four subfamilies of Iridaceae currently recognized (Goldblatt 1990, 2001 ), Crocoideae comprise about 995 species, slightly more than half the total species in the entire family
Taxa included in the phylogenetic analyses are listed in Appendix 1 together with voucher information and European Molecular Biology Laboratory (EMBL) nucleotide sequence database accession numbers
Using DNA sequences of the six plastid DNA regions listed above from one species each of 27 genera of Crocoideae, plus 34 other genera of Iridaceae, and four outgroup genera combined in one matrix, together with results from a gap analysis and with successive weighting, we obtained a single most-parsimonious tree
Summary
One of four subfamilies of Iridaceae (order Asparagales) currently recognized (Goldblatt 1990, 2001 ), Crocoideae comprise about 995 species, slightly more than half the total species in the entire family. The subfamily is a climax group within Iridaceae and includes such well known and horticulturally important genera as Crocosmia (8 spp.), Crocus 260 spp.), Sparaxis (15 spp.), and Watsonia Crocoideae are the most recently evolved of the subfamilies, probably having begun their radiation after the mid-Oligocene, ca. Synapomorphies for Crocoideae are numerous (Table 1), and comprise all organs of the plant including the rootstock (a corm), leaf anatomy, inflorescence, flower (ancestrally zygomorphic), ovules, and pollen grains
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