Reproductive morphology of Sargentodoxa cuneata (Lardizabalaceae) and its systematic implications

Abstract

The reproductive morphology of Sargentodoxa cuneata (Oliv) Rehd. et Wils. is investigated through field, herbarium, and laboratory observations. Sargentodoxa may be either dioecious or monoecious. The functionally unisexual flowers are morphologically bisexual, at least developmentally. The anther is tetrasporangiate, and its wall, of which the development follows the basic type, is composed of an epidermis, endothecium, two middle layers, and a tapetum. The tapetum is of the glandular type. Microspore cytokinesis is simultaneous, and the microspore tetrads are tetrahedral. Pollen grains are two-celled when shed. The mature ovule is crassinucellate and bitegmic, and the micropyle is formed only by the inner integument. Megasporocytes undergo meiosis resulting in the formation of four megaspores in a linear tetrad. The functional megaspore develops into an eight-nucleate embryo sac after three rounds of mitosis. The mature embryo sac consists of an egg apparatus (an egg and two synergids), a central cell, and three antipodal cells. The pattern of the embryo sac development follows a monosporic Polygonum type. Comparisons with allied groups show that Sargentodoxa shares more synapomorphies with the Lardizabalaceae than other Ranunculales. Characteristics of its reproductive morphology are consistent with the placement of Sargentodoxa as the sister group of the remaining Lardizabalaceae. It does not possess a sufficient number of apomorphic characters to justify its separation into a separate family or subfamily. It is best retained as a member of the Lardizabalaceae.

Embryo sac formation and early embryo development in Agave tequilana (Asparagaceae)

“…Occasionally, sacs with less than eight nuclei are found in many species and this can be due to a rapid degeneration of the antipodals or they may go unnoticed because they are hidden at the end of the chalazal tube (Maheshwari 1948 , 1950 ). This phenomenon of rapid disintegration of the antipodal cells has been reported for several plant species, such as Agave virginica (Regen 1941 ), Glycine max (Kennell and Horner 1985 ), Scilla persica (Svoma and Greilhuber 1988 ), Triticum aestivum (Zhang et al 1988 ; An and You 2004 ), Arabidopsis thaliana (Murguia et al 1993 ), Passiflora edulis (Magalhães de Souza et al 2002 ), Sargentodoxa cuneata (Wang et al 2009 ) and Cichorium intybus (Chehregani et al 2011 ).…”

The complete chloroplast genome sequence of Sargentodoxa cuneata: genome structure and genomic resources

“…Sargentodoxa cuneata; molecular markers; SSR Sargentodoxa, a monotypic genus of the Lardizabalaceae has often been placed in its own family, Sargentodoxaceae (Hoot et al 1995). It consists of the single species, Sargentodoxa cuneata (Oliver) Rehder and E. H. Wilson, mostly confined to subtropical China (Wang et al 2009). S. cuneata is used as traditional Chinese medicine or ethnic medicine (called Hongteng or Xueteng).…”

Quantifying Meiosis: Use of the Fractal Dimension, Df, to Describe and Predict Prophase I Substages and Metaphase I

“…1D) can also be mined for microsporocytes and D f calculation. As with megasporogenesis, these species undergo microsporogenesis in the late fall, in the last three weeks in November (Wang et al, 2009a(Wang et al, , 2009b.…”

“…1D), members of the Lardizabalaceae found in China and other Southeast Asian countries. Both are "winter bud" species that undergo megasporogenesis over three weeks (typically the last three in November) in the late fall (Wang et al, 2009a(Wang et al, , 2009b.…”