Table 2. Key Features of B. distachyon, B. stacei, and B. hybridum.
| Trait | B. distachyon | B. stacei | B. hyridum |
|---|---|---|---|
| Ploidy | Diploid | Diploid | Allotetraploid |
| Annual | Yesa | Yes | Yes |
| Originb | ∼7 Mya (lineage) ∼1 Mya (species) | ∼10 Mya (lineage)c | ∼1 Mya (species)c |
| Chromosome | 2n=2x=10, x=5 | 2n=2x=20, x=10 | 2n=4x=30, x=10+5 |
| Genome size | 0.631 pg/2C 272 Mbp | 0.564 pg/2C 234 Mbp | 1.265 pg/2C 509 Mb |
| Occasional short rhizomes | No | Yes | Yes |
| Leaf blade color | Bright green | Pale green | Dark green |
| Leaf blade shape | Straight | Curled | Straight |
| Leaf softness | Brittle | Soft | Brittle |
| Leaf hairiness | Scarcely hairy or glabrous | Densely hairy | Scarcely hairy or glabrous |
| Vernalizationd | Yes | No | No |
a
Annual, although there are other Brachypodium species that are perennials.
b
Origin indicates million years ago (Mya; 106 years) since the split from a common ancestor. Lineage indicates split from the stem ancestor, and species indicates split from the crown ancestor.
c
B. hybridum is the derived allotetraploid of B. distachyon × B. stacei.
d
Vernalization is required to induce flowering. Most, but not all, B. distachyon lines require vernalization (Vogel et al., 2009).