Question

Which plant is described by these clues? The genus name is nothing more elaborate than the old Latin word Roman farmers used for cabbage. The species name is the classical Latin word for the swollen white field root the Romans grew both for the table and for stock feed. Its ten-chromosome genome forms one half of the hybrid species that supplies most of the world's canola, the other half coming from the species behind kale and broccoli. Each fruit ripens as a {silique} that splits from the base upward, the two {valves} falling away and leaving a papery oval frame, the {replum}, still strung with seed. Every flower sets four separate {petals} crosswise over six {stamens}, four tall and two short. Those four petals are a clear egg-yolk yellow, the colour shared by every crop species in its genus. At the tip of the {raceme} the open blossoms stand level with or above the cluster of unopened buds instead of being overtopped by them. Upper stem leaves are stalkless and {amplexicaul}, wrapping the stem with a pair of ear-like lobes, while the coarser lower leaves are bristly to the touch. A torn leaf turns hot and peppery within seconds, the bite made on the spot as ruptured cells convert stored {glucosinolates} into volatile oils. Genomic work points to the Hindu Kush region of central Asia as the species' homeland, though it now turns up as a weed of field edges and roadsides across the temperate world. One species covers bok choy, napa cabbage, mizuna, komatsuna and rapini; this Japanese F1 selection instead swells a smooth white globe 2 to 3 inches (5 to 8 cm) across, thin-skinned and sweet enough to eat raw, ready 38 to 45 days from sowing.

Accepted Answer

Brassica rapa 'Hakurei'

Name That Plant #115