of microsporogenesis and the position of the ovary. The 'lower Asparagales' typically have simultaneous microsporogenesis (i.e. cell walls develop only after both meiotic divisions), which appears to be an apomorphy within the monocots, whereas the 'core Asparagales' have reverted to successive microsporogenesis (i.e. cell walls develop after each division). The 'lower Asparagales' typically have an inferior ovary, whereas the 'core Asparagales' have reverted to a superior ovary. A 2002 morphological study by Rudall treated possessing an inferior ovary as a synapomorphy of the Asparagales, stating that reversions to a superior ovary in the 'core Asparagales' could be associated with the presence of nectaries below the ovaries. However, Stevens notes that superior ovaries are distributed among the 'lower Asparagales' in such a way that it is not clear where to place the evolution of different ovary morphologies. The position of the ovary seems a much more flexible character (here and in other angiosperms) than previously thought. Changes to family structure in APG III The APG III system when it was published in 2009, greatly expanded the families Xanthorrhoeaceae, Amaryllidaceae, and Asparagaceae. Thirteen of the families of the earlier APG II system were thereby reduced to subfamilies within these three families. The expanded Xanthorrhoeaceae is now called "Asphodelaceae". The APG II families (left) and their equivalent APG III subfamilies (right) are as follows: Structure of Asparagales Orchid clade Orchidaceae is possibly the largest family of all angiosperms (only Asteraceae might - or might not - be more speciose) and hence by far the largest in the order. The Dahlgren system recognized three families of orchids, but DNA sequence analysis later showed that these families are polyphyletic and so should be combined. Several studies suggest (with high bootstrap support) that Orchidaceae is the sister of the rest of the Asparagales. Other studies have placed the orchids differently in the phylogenetic tree, generally among the Boryaceae-Hypoxidaceae clade. The position of Orchidaceae shown above seems the best current hypothesis, but cannot be taken as confirmed. Orchids have simultaneous microsporogenesis and inferior ovaries, two characters that are typical of the 'lower Asparagales'. However, their nectaries are rarely in the septa of the ovaries, and most orchids have dust-like seeds, atypical of the rest of the order. (Some members of Vanilloideae and Cypripedioideae have crustose seeds, probably associated with dispersal by birds and mammals that are attracted by fermenting fleshy fruit releasing fragrant compounds, e.g. vanilla.) In