The Stomatal Ontogeny and Structure of the Liassic Pteridosperm Sagenopteris (Caytoniales) from Hungary

Abstract

Stomatal ontogeny is often inferred but rarely documented for extinct fossil plants because it requires observations from young leaves that are rarely preserved as fossils. The discovery of several very young leaves of the Jurassic plant Sagenopteris (Caytoniales) in the Mecsek Mountains (southern Hungary) in a good state of preservation provides the opportunity for studying the stomatal ontogenesis of this genus. The specimens show perigenous anomocytic stomata. This feature confirms the evolutionarily high position of Sagenopteris among fossil gymnosperms and supports the opinion that the ancestors of angiosperms and some groups of pteridosperms might be closely related. Such clear examples of stomatal development have not previously been documented for fossil material.

Several developmental and morphogenetic factors govern the evolution of stomatal patterning in land plants

“…This type of patterning, coupled with Harris' (1976) observation of 'occasional monstrous stomata' in Mesozoic bennettites, strongly indicates that stomatal development is mesogenous or mesoperigenous rather than perigenous (this paper) Caytoniales* (Sagenopteris) Stomata anomocytic/stephanocytic; development incompletely known Stomata were scored as stephanocytic by Carpenter (2005). Sagenopteris stomata were described as anomocytic (Barbacka & Bόka, 2000), or with a ring of 10-15 small subsidiary cells (Barbacka et al, 2006). Barbacka & Bόka (2000) also showed some late stages of epidermal development, including linear cell files with some recently divided cells (lacking asymmetric divisions), and some recently divided GMCs; they tentatively concluded that development is perigenous, but more data are needed to confirm this observation Angiosperms (Fig.…”

“…Sagenopteris stomata were described as anomocytic (Barbacka & Bόka, 2000), or with a ring of 10-15 small subsidiary cells (Barbacka et al, 2006). Barbacka & Bόka (2000) also showed some late stages of epidermal development, including linear cell files with some recently divided cells (lacking asymmetric divisions), and some recently divided GMCs; they tentatively concluded that development is perigenous, but more data are needed to confirm this observation Angiosperms (Fig. 7) Stomata both anomocytic and paracytic; possibly ancestrally paracytic and mesoperigenous Many types have been reported (e.g.…”

Paleoecology, Ploidy, Paleoatmospheric Composition, and Developmental Biology: A Review of the Multiple Uses of Fossil Stomata

“…Studies of fossil stomata and their associated subsidiary and neighboring cells can provide insights into the origin and evolution of developmental pathways of the stomatal complex (Barbacka and Bóka, 2000;Barclay et al, 2007;Bomfleur and Kerp, 2010;Rudall et al, 2013). This is more than just an academic exercise as a deeper understanding of the origin, evolution, and diversity of stomatal developmental pathways in both extant and extinct lineages underpins genetic engineering programs for altered stomatal conductance, assimilation rates, and leaf cooling capacities in modern crop plants.…”

The Fossil Flora of the Winthrop Formation (Albian-Early Cretaceous) of Washington State, USA. Part II: Pinophytina

“…This composite plant is the only member of the order, which is thought to be a derived and isolated group of seed ferns. Some authors have suggested that it is a possible sister-group of the angiosperms (Doyle and Hickey 1976;Donoghue 1986, 1992;Barbacka and Boka 2000), but we reject this assertion by placing it in the superclass Medullosopsae.…”