Aspects of Cone and Ovule Ontogeny in Cryptomeria (Taxodiaceae)

Abstract

The axillary complex of female cones of Cryptomeria is initiated as a tangentially extended triangular structure with a rounded apex. It is bilaterally symmetrical. Structures interpreted as prophylls are differentiated first, but they become insignificant in later development. They are succeeded by two successive pairs of lobes, each lobe being the common primordium for an adaxial ovule and a tooth. The ovule initially much exceeds the tooth. The apex of the complex has a diversity of fates and may differentiate as an ovule‐tooth pair. A one‐to‐one relation between teeth and ovules may be lost by abortion of ovules. The initial relation between teeth and ovules is obscured in later development due to extension of tissues at the base of the complex associated with considerable enlargement of the teeth. Histogenesis of the various parts is described, together with the vascular system. There is a vascular supply to the tooth but not the ovule. The results support a direct comparison with the extinct transition conifers Pseudovoltzia and Aethophyllum but do not fully support Florin's generalized model for the arrangement of parts in the axillary complex of conifers.

AGAMOUS subfamily MADS-box genes and the evolution of seed cone morphology in Cupressaceae and Taxodiaceae

“…Cryptomeria seed cones bear ovules and teeth that develop from common ovule–tooth primordia in the axils of bracts (Takaso and Tomlinson 1989a). In these cones CjMADS4 is expressed in the common primordium already before the ovule and the tooth can be distinguished morphologically (Fig.…”

“…The C. japonica tooth develops from the same axillary primordium as the ovule (Takaso and Tomlinson 1989a). Our data show that the Cryptomeria DAL2 / SAG1 ortholog CjMADS4 is expressed in the ovule–tooth primordium, which in itself might be interpreted as consistent with the tooth being an ovuliferous scale.…”

“…In Cryptomeria japonica (Taxodiaceae), scales referred to as “teeth” develop between the ovules and the subtending sterile bracts. In this species, the tooth and the ovule develop from the same axillary organ primordium (Takaso and Tomlinson 1989a). In other Taxodiaceae species, scales also develop in positions between the ovules and the bract (Takaso and Tomlinson 1990, 1992; Tomlinson and Takaso 2002; Farjon and Ortiz Garcia 2003).…”

The ontogeny of disparity in Cupressaceae seed cones

“…All Cupressaceae cones are initially open, in the sense that their cone scales are loosely arranged and their ovules (or at least ovule micropyles) are exposed to the environment and capture windborne pollen on their pollination droplets (Owens et al ., 1998; Tomlinson & Takaso, 2002; Farjon, 2005; Dörken & Jagel, 2014). Immediately after pollination, Cupressaceae cone scales undergo patterns of intercalary growth and expansion specific to taxa (Takaso & Tomlinson, 1989, 1992; Tomlinson et al ., 1993; Zhang et al ., 2004) but which all ultimately result in cone scales that cover seeds. This expansion primarily occurs either in the abaxial‐adaxial direction, creating proportionally thick peltate structures that contact neighboring scales via polygonal interlocking faces (see Figs 1c, 2b), or in the direction of scale margins, creating broad but relatively thin laminar structures.…”