Foxtail (Setaria spp.) Seed Hull
Topography
Foxtail (Setaria spp.) Seed Hull
Topography HYPOTHESIS:
The morphology of the foxtail seed outer envelope surfaces (hull, glumes) are
shaped to accomplish three (3) things crucial to the transduction of soil
environmental inputs heat, water, oxygen and other gases to the seed symplast,
thus regulating seed behavior:
1. morphologically enhanced accumulation of gas and liquid phase soil water on the seed surface by means of providing attracting, gathering topography appropriate to the local soil particle size heterogeneity and moisture availability;
2. morphologically enhanced passive oxygenation of seed surface water by means of increased surface area and optimal topography;
3. morphologically enhanced passive transport of oxygen-laden moisture from the seed surface and soil to the placental pore by means of capillarity- and channeling-optimized topography.
Below left & right, bottom: Lemma (top) side of seed showing both
transverse and longitudinal ridges on hull surface
Below right, top: Palea (bottom) side, note white placental pore at extreme right
(basal) end of seed. This is the only water entry point to the embryo.
Below: Lemma (upper) part of seed with papery glumes present, covering the basal 2/3 of seed.
Below: Palea (bottom) part of seed. Notice the longitudinal ridges and the white placental pore (left, basal end of seed) that was the point of attachment to the parental panicle.
Yellow foxtail seed with lemma (top) part showing. Note the more defined hull transverse ridges, the lemma side glume covering only 0.4 of the hull, the sterile spikelet (left, small with glumes) and the setae (bristles) projecting upward from the seed base. The dark brown projection (very top, left) from the top of the seed is the remnant of the floral (stigma, anther) parts.
View of the basal end of the giant foxtail (Setaria faberii) seed. The germination lid (top center) has allowed the coleorhiza within to slightly protrude from the lemma (top) portion of the hull. Palea part of the hull bottom. Notice the pedicel-vascular connection juncture scar at the basal end of the seed (center).
Side view of the germination lid opening slightly to allow the slightly protruded coleorhiza to emerge from within the lemma portion of the seed hull.
