Floral Development and Embryology in the Early‐Divergent Grass Pharus

Microsporogenesis is simultaneous in the early‐divergent grass Streptochaeta, but successive in the closest grass relative, Ecdeiocolea

“…One unusual feature found in Streptochaeta spicata is the relatively thin endothecium, in contrast to the persistent, fibrous endothecium of many other grasses. A thin endothecium was also reported for the early-divergent grass Pharus (Sajo et al, 2007), indicating that it could represent a plesiomorphic state for the family. Some other character conditions that are apparently infrequent within Poaceae but occur in other Poales could also represent grass plesiomorphies.…”

“…Meiosis does not appear to be synchronous within a locule in Ecdeiocolea, since Furness & Rudall (1999) and references therein, also Bromeliaceae (Sajo et al, 2005), Prionium (Munro & Linder, 1997), Cyperaceae (Simpson et al, 2003), Joinvilleaceae (Bayer & Appel, 1998), Ecdeiocoleaceae, Anomochlooideae (this paper), Pharoideae (Sajo et al, 2007), other Poaceae (Bhanwra, 1988;Bhanwra et al, 1991 Linder & Rudall (2005). Anther wall development type from: Bromeliaceae (Sajo et al, 2005), Typha (Asplund, 1972), Sparganium (Mü ller-Doblies, 1969), Rapateaceae (Tiemann, 1985;Venturelli & Bouman, 1988), Prionium (Munro & Linder, 1997), Cyperaceae (Khanna, 1963;Makde, 1982), Juncaceae (Munro & Linder, 1997), Mayaca (Venturelli & Bouman, 1986), Xyris (Rudall & Sajo, 1999), Eriocaulaceae (Monteiro-Scanavacca & Mazzoni, 1978;Arekal & Ramaswamy, 1980), Abolboda (Tiemann, 1985), Restionaceae (Krupko, 1962), Centrolepidaceae (Hamann, 1975), Flagellaria (Munro & Linder, 1997), Anomochlooideae (this paper), Pharoideae (Sajo et al, 2007), other Poaceae (Bhanwra, 1988;Bhanwra et al, 1991 dyads and tetrads are present together, which is unusual. Among other monocots, such reversals in microsporogenesis type can occur occasionally, for example, most lower asparagoids (Asparagales) are simultaneous, with a reversal to the successive type in Hypoxidaceae and within Iridaceae (Rudall et al, 1997;Penet et al, 2007).…”

“…The simultaneous condition in Streptochaeta is highly unusual for grasses, in which only successive microsporogenesis ( Figure 5A) has previously been reported (Furness & Rudall, 1999;Sajo et al, 2007). Microsporogenesis is usually constant within angiosperm families (Furness & Rudall, 1999;Furness et al, 2002).…”

“…Successive microsporogenesis also predominates in most other members of the order Poales, but one exception is the sedge family Cyperaceae, in which microsporogenesis is of the simultaneous type, associated (except in subfamily Mapanioideae, tribe Hypolytreae) with a highly unusual system of programmed cell death (Furness & Rudall, 1999;Simpson et al, 2003). Thus, our preliminary observation of tetrahedral tetrads in an early-divergent grass genus, Streptochaeta prompted us to investigate this aspect further, in the context of ongoing comparative studies on early-divergent grasses and their allies Grana, 2009;48: 27-37 (Rudall et al, 2005;Sajo et al, 2007Sajo et al, , 2008. In this paper, we describe stamen, anther and pollen development in Streptochaeta spicata Schrad., one of only three species of Streptochaeta, a herbaceous grass from shaded tropical forests in Brazil that belongs in one of the early-divergent grass lineages, Anomochlooideae (GPWG, 2001).…”

Desenvolvimento de óvulo, fruto e semente de espécies de Poaceae (Poales)

“…Para as espécies de Bambusoideae observou-se que, apesar de possuírem primórdio bizonado, o óvulo apresenta nucelo desenvolvido em relação às demais espécies estudadas, além do óvulo e da semente apresentarem tamanho maior. Nas espécies de Pharus, atualmente pertencentes à Pharoideae, e antes incluídos em Bambusoideae, o óvulo também apresenta nucelo desenvolvido (Sajo et al 2007). Em espécies de Ecdeiocoleaceae, grupo irmão de Poaceae, pertencente ao clado "graminídeo", este caráter também foi relatado (Linder & Rudall 2005) e pode ser compartilhado entre as espécies das duas famílias.…”