2006, 2010) speculated that the gynoecium of Tofieldia and Japonolirion, in which septal nectaries are triradiate and infralocular, is probably closely similar to that of the hypothetical extinct common ancestor of monocots, and could represent a primitive gynoecial type in monocots.
Evolution of the monocot gynoecium: evidence from comparative morphology and ontogeny in Tofieldia, Japonolirion, Petrosavia and Narthecium.
The sieve-element plastids of Japonolirion osense match those of Asarurn and Saruma, in both size and composition: they contain a dense polygonal and several equally dense cuneate crystals (Fig.
cp] sieve-element plastids identical to those of Japonolirion (Figs.
Tamura (1998) treats Japonolirion as a monotypic tribe placed together with Tofieldieae and Petrosavieae in the subfamily Tofieldioideae, which he combines with Narthecioideae in his Nartheciaceae.
Phylogenetic trees using DNA data to demonstrate relationships among angiosperms 1) support Japonolirion (together with Petrosavia, now treated as Petrosaviaceae) in a dade branching after Acorus and after Alismatales sensu APG (1998) as sister to the main body of monocotyledons, 2) include Tofieldiaceae, together with Araceae in the latter, second-most basal dade ofmonocotyledons, and 3) associate Nartheciaceac s.
cp] plastids of Japonolirion would have retained the polygonal crystal, while all other monocotyledons had lost it; e.
Therefore, summarizing the structural evidence from sieve-element plastids, Japonolirion and the Tofieldiaceae are identified as basal monocotyledons that share a common ancestry with aristolochiid eumagnoliids.