AoB PLANTS

Zingiberales seed morphoanatomy

Three-dimensional volume rendering of a Calathea inocephala (Marantaceae) seed with the perisperm canal—a feature unique to this family—digitally dissected (in green) and cupped by a J-shaped embryo. Image source: J.C. Benedict & S.Y. Smith.

The banana and ginger group, order Zingiberales, is an exceptionally diverse group of primarily tropical plants. Within Zingiberales, the ginger family (Zingiberaceae) is unique in being not only the most species-rich but also the most disparate in terms of their morphology and anatomy, and the only group with a substantial number of species in temperate environments. In a recent study published in AoB PLANTS, Benedict et al. found that multiple radiations into temperate habitats were not driven by morphological change, but instead may be due to a genetic plasticity in the family that provided opportunities for speciation events not found anywhere else in the order. Indeed, the notable morphoanatomical variety in Zingiberaceae seeds may account for their extraordinary ecological success and high species diversity as compared to other Zingiberales.

Seed anatomy in Lowiaceae.
Seed anatomy in Lowiaceae. (A, E–F, J–K, O): light micrographs; (B–C, G–H, L–M): SRTXM digital longitudinal sections; (D, I, N): SRTXM digital transverse sections. (A–E) Orchidantha maxillarioides . (A) Overview of light brown seed covered in trichomes with two-stranded thick lobed aril (a). (B) Internal morphology showing embryo (em) and endosperm (es). (C) Micropylar region with aril (a), multilayered operculum (o), hilar rim (hr) of mesotesta and exotesta, embryo (em) and endosperm (es). (D) Seed coat with isodiametric exotesta (ex), mesotesta (m) of two cell types and elongate, sclerenchymatous endotesta (en). (E) Detail of striate seed surface with numerous trichomes (one at arrow). (F–J) Orchidantha sabahensis . (F) Overview of light brown seed with thick lobed aril (a). (G) Internal morphology showing embryo (em) and endosperm (es). (H) Micropylar region with single layered operculum (o), hilar rim (hr) of exotesta and mesotesta and aril (a). (I) Seed coat with isodiametric exotesta (ex), mesotesta (m) of two cell types and elongate, sclerenchymatous endotesta (en). (J) Detail of striate and verrucose seed surface with trichomes (arrow). (K–O) Orchidantha vietnamica . (K) Overview of tan seed. (L) Internal morphology; no embryo or nutritive tissues were present. (M) Micropylar region with hilar rim (hr) of exotesta and mesotesta and single layered operculum (o). (N) Seed coat with isodiametric exotesta (ex), mesotesta (m) and endotesta (en) of elongate sclerenchyma. (O) Detail of striate and verrucose seed surface with trichomes. * indicates mounting glue and/or specimen stub. Scale bars: A, F, G, K = 1 mm; B, H, L, M = 500 µm; C, E, J, O = 250 µm; D, I, N = 100 µm. Image: Benedict et al. (2016)

Reference

Benedict, J. C., Smith, S. Y., Specht, C. D., Collinson, M. E., Leong-Škorničková, J., Parkinson, D. Y., & Marone, F. (2016). Species diversity driven by morphological and ecological disparity: a case study of comparative seed morphology and anatomy across a large monocot order. AoB Plants, 8, plw063. http://dx.doi.org/10.1093/aobpla/plw063

About the author

AoBPLANTS

AoB PLANTS is an open-access, online journal that publishes peer-reviewed articles on all aspects of environmental and evolutionary biology. Published by Oxford University Press, AoB PLANTS provides a fast-track pathway for publishing high-quality research, where papers are available online to anyone, anywhere free of charge. Reasons to publish in AoB PLANTS include double-blind peer review of manuscripts, rapid processing time and low open-access charges.