Gynoecium diversity and systematics of the Magnoliales and winteroids

Abstract

Carpel and ovule structure was compared in representatives of all 11 families of the Magnoliales (Annonaceae, Canellaceae, Degeneriaceae, Eupomatiaccae, Himantandraceae, Magnoliaceae, Myristicaceae) and winteroids (Austrobaileyaceae, Illiciaceae, Sehisandraceae, Winteraceae). Special attention was paid to features that are constant at family level. Bisexual flowers are always protogynous. In all representatives studied the carpels are closed at anthesis. Caipel closure is attained in three different ways: (1) postgenital fusion of inner surfaces (Degeneriaceae, Eupomatiaccae. Winteraceae), or (2) occlusion by secretion (Austrobaileyaceae, Sehisandraceae), or (3) a combination of (1) and (2): in Annonaceae, Canellaceae, Myristicaceae there is a conspicuous secretory canal in the innermost part of the ventral slit; in Illiciaceae and Magnoliaceae there is a narrow canal in the innermost part of the ventral slit; and in Himantandraceae the ventral slit is postgenilally fused in the style but completely open in the ovary. In most families the carpels have a double stigmalic crest or they have two tips in the transversal symmetry plane (i.e. at right angles to the median plane). Stigmas are unicellular papillate in most families but the papillae are bi‐to multicellular (uniseriate) in Degeneriaceae and Eupomatiaceae. An unusual cryptic exlracarpellary compitum was found in Himantandraceae and Sehisandraceae. Intrusive oil cells were found in the carpel epidermis of Illiciaceae and Sehisandraceae. Mature ovules vary in length between 0.15 and 1.1 mm. The outer integument is fully annular (not semiannular) in Degeneriaceae, Himantandraceae, Canellaceae, Myristicaceae, and Illiciaceae. A rudimentary aril occurs in Canellaceae, and originates at the same site as in arillate Annonaceae and Myristicaceae. The results most strongly support an Annonaceae‐Myristicaceae‐Canellaceae alliance, to some degree also an Eupomatiaccac‐Degeneriaceae‐Himantandraceae‐Magnoliaceae alliance, and an Illiciaceae‐Schisandraceae‐Winteraccae‐Austrobaileyaceae alliance.

Seed coat thickness in the evolution of angiosperms

“…More rarely, angiosperm ovules can be endostomic or exostomic if only the ii or the oi, respectively, generate the micropyle [18]. Endostomic ovules show distal thickening of the ii at the micropyle where the ii is not covered by the oi, suggesting that oi limits ii growth [38]. Thickening of the distal region of the integument might be instrumental to enclose the nucellus apex and form a micropylar pore.…”

“…Lobed iis have been considered remnants of ancestral integuments or a sign of atavism as paleozoic ovules displayed a lobbed integument [83]. Nevertheless, it has been argued that lobation might have evolved as a way to restrict the circumference of the integument and allow the formation of a micropyle, as an alternative mechanism to distal integument thickening [38]. …”

Floral ontogeny of Knema and Horsfieldia (Myristicaceae): evidence for a complex androecial evolution

“…The gynoecium consists of a single pistil with a sessile, bilobed stigma and a single anatropous ovule (cf. Igersheim & Endress, 1997). Fruits consist of a single carpel with a visible longitudinal slit ( Fig.…”

Evolution of syncarpy in angiosperms: theoretical and phylogenetic analyses of the effects of carpel fusion on offspring quantity and quality

“…Information on the nature and degree of carpel fusion was drawn from Cronquist (1981), Endress (1982Endress ( , 1995, Endress et al (1983), Williams et al (1993), Igersheim & Endress (1997), Svoma (1998), and Endress & Igersheim (2000). We wished to distinguish between apocarpy, complete syncarpy, and partial syncarpy and, when the last condition, among the various sites of partial carpel fusion.…”