Scilloideae - Phylogeny

Phylogeny

There exists considerable disagreement among scholars about the exact limits of the subfamily, the number of genera that should be included and which taxa should be included. The taxonomy is in a state of flux and has been evolving, informed by newer cytogenetic, morphological and molecular data.

The monophyly of Scilloideae is supported by molecular data, which also give support to the exclusion of Camassia, Chlorogalum and related genera, i.e. the former Hyacinthaceae subfamily Chlorogaloideae of which Chlorogalum was the type genus (Chase et al. 1995a, Speta 1998). These genrea are now regarded as members of the Agavoideae, distinguished from Scilloideae (sensu stricto Hyacinthaceae) by their bimodal karyotype, the combination of more or less globose seeds with a testa firmly attached, tepals that are usually multiveined and stigma that are distinctly three-lobed.

The exact location of Scilloideae within Asparagales is unclear, but may be related to the Brodiaeoideae (formerly Themidaceae), and these two clades may be associated with Agavoideae or, less probably, with the group consisting of Allioideae (formerly Alliaceae) and Amaryllidoideae (Chase et al. 1995a, 2000, Rudall et al. 1997a, b, Fay et al., 2000, Soltis et al. 2000 ). This lack of certainty in the location of the clade in the order Asparagales makes the determination of synapomorphy morphological problematic, although the presence of poisonous bulbs and steroids is remarkable. The indeterminate inflorescence (usually racemose or spike) easily distinguishes the Scilloideae from Brodiaeoideae, Allioideae and Amarillidoideae (Amaryllidaceae sensu stricto), all of which have umbellate inflorescences. A herbaceous habit and the presence of bulb distinguishes Scilloideae from Agavoideae. The Asparagales page provides an overview of the cladic structure of this order.

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