Flower structure and development of Araceae compared with alismatids and Acoraceae

Abstract

Floral development of Araceae is compared with that of other basal monocots such as alismatids and Acorus. Flowers of Araceae, Acorus and several alismatids with spicate inflorescences lack a subtending floral bract. In Araceae and some Potamogetonaceae the subtending floral bract is suppressed, and not incorporated into the perianth. This differs from Acorus and some alismatids, where a bract-like median abaxial tepal is formed in the outer perianth whorl (i.e. developmental merger of flower-subtending bract and tepal). In Araceae, Acorus and spicate alismatids flowers develop unidirectionally, correlated with bract reduction. Araceae lack unidirectionality in the outer perianth whorl, in contrast t o Acorus and Juncaginaceae. The transition from trimerous to dimerous flowers in Onintiurn (Araceae) is by accentuation of the unidirectionality of the inner perianth. The gynoecium of Araceae and Acorus is synascidiate. However, in most Araceae the synascidiate portion is shorter than in Acorns, and a distinct basal elongation phase as in Acorus and Juncaginaceae was not found. The perianth and androecium of Lysichiton and Symplocarpus and the gynoecium of Gymnostachys differ from other Araceae and resemble those in Potamogetonaceae. Developmental findings support the isolation of Acorus from Araceae, and show similarities of Araceae with Potamogetonaceae and of Acorus with Juncaginaceae.

Patterns of Floral Structure and Orientation in Japonolirion , Narthecium, and Tofieldia

“…The direction of initiation of the inner tepal s is the reverse of the outer. In basal monocots, when the bracteole is absent, the sequence of perianth initiation is either simultaneous in each whorl or unidirectional, but seemingly never spiral (e.g., Endress 1995; Buzgo and Endress 2000;Buzgo 2001; our data). We have not yet observed sequences of perianth development in Japonolirion and Narthecium, but predict that they have a similar pattern of floral initiation to that of Allium and Lilium.…”

“…Formation of " hybrid " organs that comb ine characters of the flower-subtending bract and the first median abaxial phyllome on the pedicel is a feature common to T. pusilla and some other Alismatales, such as Aponogetonaceae, Juncaginaceae and Potamogeton densus L. (Potamogetonaceae), in addition to the putatively basal monocot, Acarus (Posluszny and Sattler 1973;Buzgo and Endress 2000;Buzgo 2001;Remizova and Sokoloff 2003). Formation of similar bract-like organs may be regarded as additional morphological evidence for a close relationship between these taxa.…”

“…10), Aponogetonaceae, Juncaginaceae, and Potamogeton L. this is the outer median tepal. According to Buzgo (2001), in Alismatales s.l., unidirectional development is often correlated with structures resembling subtending bracts (and absence of a true bract), and with formation of peloria (or more precisely, terminal flower-like structures: Buzgo et al 2004). Our data show no such correlation in Tofieldia.…”

“…Buzgo and Endress (2000), Buzgo (2001), and Buzgo et al (2006) compared in detail the floral morphology of some basal monocot groups such as Acoraceae (Acorales) and Araceae (Alismatales), and demonstrated the taxonomic importance of the pattern of floral orientation and presence/absence of a bract. Here we investigate these features in some former Melanthiaceae s.l., especially in the relatively basal monocot Tofieldia Huds.…”

The Maize PI/GLO Ortholog Zmm16/sterile tassel silky ear1 Interacts with the Zygomorphy and Sex Determination Pathways in Flower Development

“…After a comparative morphological study of grass flowers, they hypothesized that the placement and shape of the palea produces an inhibitive zone that represses initiation and growth in neighboring organs of other whorls. Such inhibitive zones, created by prominent or precocious development of particular floral organs, have been frequently noted in comparative morphological studies in other systems as well (Hofmeister, 1868;Buzgo, 2001;Remizowa et al, 2013). At the molecular level, such a palea inhibition zone could be explained by auxin dynamics in the floral meristem.…”