Raphanus

1. Petals yellow to white (but sometimes drying pale lilac), usually with conspicuous dark veins, especially when fresh; mature fruit at most ca. 4 mm broad, strongly constricted between the seeds (often with 4 or 5 (–9) seeds) and strongly corky-ribbed over the seeds.

R. raphanistrum

1. Petals purple or sometimes white; mature fruit ca. 8–12 mm broad, not constricted or ribbed over the seeds, usually 2–3-seeded.

R. sativus

All species found in Raphanus

Raphanus raphanistrumWILD RADISH 
Raphanus sativusRADISH 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 10, 2018. https://michiganflora.net/genus.aspx?id=Raphanus.