Gynoecium diversity and systematics in basal monocots

Abstract

Gynoecium and ovule structure was comparatively studied in representatives of the basal monocots, including Acorales (Acoraceae), Alismatales (Araceae, Alismataceae, Aponogetonaceae, Butomaceae, Hydrocharitaceae, Juncaginaceae, Iimnocharitaceae, Potamogetonaceae, Scheuchzeriaceae, Tofieldiaceae), Dioscoreales (Dioscoreaceae, Taccaceae), and Triuridaceae as a family of uncertain position in monocots. In all taxa studied the carpels or gynoecia are closed at anthesis. This closure is attained in different ways: (1) by secretion without postgenital fusion (Araceae, Hydrocharitaceae); (2) by partly postgenitally fused periphery but with a completely unfused canal (Alismataceae, Aponogetonaceae, Butomaceae, Limnocharitaceae, Scheuchzeriaceae, Dioscoreaceae, Taccaceae); (3) by completely postgenitally fused periphery but with an unfused canal in the centre (Acoraceae, Tofieldiaceae); (4) by complete postgenital fusion and without an (unfused) canal (Juncaginaceae, Potamogetonaceae). In many Alismatales (but without Araceae) carpels have two lateral lobes. The stigmatic surface is restricted to the uppermost part of the ventral slit (if the carpel is plicate); it is never distinctly double-crested (Butomaceae?). Stigmas are commonly unicellular-papillate and secretory in most taxa. The locules are filled with a (often) mucilaginous secretion in a number of taxa. Superficial (probably intrusive) ethereal oil cells were found in the carpel wall of Acorus granaineus (as in Piperales!). Idioblasts in carpels are otherwise rare. A number of basal monocots has orthotropous ovules, which is perhaps the plesiomorphic condition in the group. The presence of almost tenuinucellar (pseudocrassinucellar) ovules is relatively common (Acoraceae, many Araceae, some Alismatales s.s.), whereas completely tenuinucellar ovules are rare and do not characterize larger groups. However, crassinucellar ovules occur in the largest number of families among the study group (basal Araceae, many Alismatales s.s.) The outer integument is always annular in orthotropous ovules. The inner integument is often lobed and it mostly forms the micropyle, whereas the outer integument is always unlobed. Gynoecium structure supports the isolated position of Acoraceae as sister to all other monocots. However, in an overall view, if compared with all other families, Acoraceae clearly shows the greatest similarities with Araceae.

Gynoecial ontogeny of Anthurium: contributions for floral developmental studies in Araceae (Alismatales)

“…Endress (1994) simplified the terminology maintaining the synascidiate, symplicate, and asymplicate zones and considered the hemisymplicate zone as part of the symplicate one. The present study follows the interpretation proposed by Endress (1994), which is used in most anatomical studies on Araceae and related families (e.g., Buzgo and Endress 2000;Igersheim et al 2000;Buzgo 2001). …”

“…All Anthurium species studied here show mucilage within their ovary locules, a well documented feature in Araceae, with variation on its production site (Eyde et al 1967;Igersheim et al 2000;Buzgo 2001). In most genera, mucilage is secreted by ovarian trichomes (French 1987;Mayo 1989;Poli et al 2012), but in Rhaphidophora sylvestris Engl.…”

Flower structure and development of Araceae compared with alismatids and Acoraceae

“…Ovules in basal true Araceae are generally anatropous, with some deviations (this study, for a review see Igersheim, Buzgo & Endress, 2001). In most Araceae the micropyle is formed by both integuments.…”

Developmental morphology of the flower of Anaphyllopsis americana and its relevance to our understanding of basal Araceae

“…flowers . The main contributions in this context are those of Buzgó (1999Buzgó ( , 2001 and Igersheim et al (2001) who analysed the anatomy and developmental floral morphology of a few basal Araceae (Gymnostachys, Orontium, Lysichiton, Pothos, Pothoidium, and Spathiphyllum) from a phylogenetic perspective, as well as a study by Poisson (1996) on the development of the flowers of Dracontium.…”