Fig. 2. (a) Spikes of F₁ hybrid and parents. From left to right: wheat, F₁ (jointed goatgrass = female parent), F₁ (wheat = female parent), and jointed goatgrass. (b) Roots of F₁ plants with maternal jointed goatgrass spikelet attached at the crown (left) and maternal wheat seed attached at planting depth (right). (c) Spikes of hybrids grown from Oregon backcross seed showing range of variation from jointed goatgrass-like (left) to wheat-like (right). (d) Spike examples illustrating potential steps of introgression from F₁ hybrid (first and second to right) via a jointed goatgrass-like backcross hybrid (center) toward jointed goatgrass (left).